To see the other types of publications on this topic, follow the link: Volumetric 3D.
Dissertations / Theses on the topic 'Volumetric 3D'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Volumetric 3D.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Khan, Javid. "Holographic volumetric 3D displays." Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2852.
Full textAbstract:
The development of a true three-dimensional display that can recreate the light field of an object or scene has been a research goal over the past century. This has recently intensified with the increase in content and proliferation of 3D data across many fields of science and engineering. The literature says that the best approaches to the problem includes holography. The research community has been busy developing the ideal holographic display. However, there are considerable technological challenges that must be overcome before this is a viable proposition. The solutions proposed in this thesis turn the problem around and take a bottom-up view, rather than the traditional top-down one. It turns out that placing certain constraints on the image enables practical implementations of holographic displays. The approach begins with low information content building up towards higher resolution displays by exploring various techniques aimed at improving performance. The work starts with empirical experimental methods that lead to a framework with theory, numerical methods, simulations and tools to design displays. The results are large, bright displays viewable under ambient conditions with human interaction. The work opens up a new avenue of research that lies between volumetric technology and contemporary holographic display research.
2
Li, Shuo. "Registration of 3D Volumetric CT Images." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-162599.
Full textAbstract:
This master thesis aims to develop a system for analyzing transformation between two volumetric CT images. The volumetric image data we process is taken from a composite material. This composite material combines wood fibre and plastic and can be used to make for instance hockey sticks or furniture. Because of the wood fibre embedded in this composite material, it absorbs water and sometimes deforms. By observing volumetric images generated by micro computed tomography (micro-CT), we know that the organization of fibre embedded in this material is very complicated. This makes it difficult to predict the deformation on beforehand. In our study, we have seen rigid transformations, non-rigid transformations and even discontinuities transformations (cracks). For a pair of very small sub volumes, in dry and wet condition, we have found that the transformation can approximated by a rigid transformation combined with a scaling value. To find this transformation, our system includes two key phases. In the first phase, we extract feature points in dry and wet condition. In the second phase, we register the feature points derived from dry and wet condition. In the feature point extraction phase, we have adapted different methods, for instance the Scale- Invariant Feature Transform (SIFT) method is used to extract features. In the registration phase, we have tested three different registration algorithms. The first algorithm is based on concepts from Random Sample Consensus (RANSAC). The second algorithm is inspired from the Iterative Closest Point (ICP) method. The third method is a novel algorithm that we call Spatial Invariant Registration. In the report, we compare the different methods in the feature extraction phase and in the registration phase. Finally, we discuss how our system can be extended to give better results with better accuracy.
3
Schwarz, Adam James. "Considerations on volumetric 3D display systems." Thesis, University of Canterbury. Electrical and Electronic Engineering, 1994. http://hdl.handle.net/10092/7572.
Full textAbstract:
The requirements of display systems are governed by the manner in which the visual world is perceived. An overview of the human visual system, including a discussion of depth cues, is presented and this is followed by a review of 3D display techniques, which includes a comprehensive discussion of volumetric systems. Volumetric displays in which the display volume is swept out by the periodic motion of a 2D screen are termed swept-volume displays; one such system, known as the Cathode Ray Sphere (CRS), is discussed in detail. A number of swept-volume displays, including the CRS, employ a rotating target screen addressed by radiation beams from sources which are stationary with respect to the screen motion. Regions of the display volume which correspond to the beam impinging on the screen at very acute angles are difficult to address accurately and are termed dead zones. The form and position of these regions is determined for both planar and helical screen geometries, and the dependence on the position of the beam source is shown. One particular configuration, namely a planar screen addressed by an equatorial beam source, is examined in detail, and a comprehensive investigation of the factors contributing to the dead zone is presented. The extra dimension of the display space makes an exhaustive raster-type scan of the display volume difficult to achieve on displays in which the voxels are generated sequentially; only the visible voxels comprising the image are thus depicted. Two procedures to order the voxels for display on swept-volume displays such as the CRS are introduced, and the dependence of their optimum performance on the values of certain system parameters is determined. The performance of the two methods is compared on the basis of the voxel positioning error in the direction of screen motion. Volumetric displays which do not employ a moving component to create the volume are termed static volume displays; one means of generating voxels in such a volume is to employ a two-step excitation of fluorescence process. The rate equations governing a simple model system encapsulating this mechanism are determined and solved numerically to indicate the relative timing of the two pumping radiation pulses that maximises the brightness of the resultant voxel. The nonuniformities and anisotropies in certain image quality parameters, such as voxel density, which arise in the display volume are discussed for a range of volumetric techniques, both swept and static volume. A filtering operation included in the graphics pipeline is proposed as a means of ensuring the display volume provides a uniform voxel density. A number of images, image sequences and simple application programs, created to evaluate the visualisation capabilities of the CRS, are discussed.
4
Bala, Druhin. "Volumetric Degenerative Routing for 3D Network-On-Chip." Thesis, North Dakota State University, 2014. https://hdl.handle.net/10365/27297.
Full textAbstract:
As we reach the limits of scaling down of circuits, Three Dimensional Integrated Circuits (3D ICs) offer a very promising opportunity to keep on increasing the processing capacities and speed. In a Multi-Processor System-on-Chip (MPSoC) based embedded system with Network-on-chip (NOC) as the communication architecture, routing of the traffic among the Processing Elements (PEs) contributes significantly to the global latency, throughput and energy consumption. Almost all prior studies have focused on 2D NOC designs. The field of 3D integration is relatively new and has emerged to provide an alternate solution for high performance computation. This paper introduces a new routing algorithm which aims to improve performance characteristics of conventional existing algorithms. Volumetric Degenerative Routing, as proposed in this paper, reduces maximum delay by as much as 40%.
5
Diskin, Yakov. "Volumetric Change Detection Using Uncalibrated 3D Reconstruction Models." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1429293660.
Full text
6
Briggs, James R., Michael R. Deis, and Jason Geng. "VOLUMETRIC 3D VISUALIZATION OF TEST AND EVALUATION OPERATIONS." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/606823.
Full textAbstract:
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, NevadaTime-Space-Position-Information (TSPI) visualization systems used today at the Air Force Flight Test Center (AFFTC) and simulation visualization tools used at the Air Armament Center (AAC) utilize two-dimensional (2D) display systems for both real-time and post-mission data analysis. Examples are monitors and large screen projection systems. Some TSPI visualization systems generate three-dimensional (3D) data as output, but the 3D data is translated so that it is compatible with 2D display systems. Currently, 3D volumetric display systems are being utilized by the Federal Aviation Administration (FAA) for monitoring air traffic in 3D without 3D goggles. The aircraft’s position information is derived from radar and fed to a volumetric display. The AFFTC and AAC need a similar system for Open Air Range testing utilizing the Global Positioning System (GPS) as the source of position information and Installed Systems Testing utilizing 6 Degree of Freedom (DOF) flight simulation data as the source of position information. This system should be capable of displaying realistic terrain structures, vehicle models and physical test configurations along with text data overlays. The ability to display the mission in real-time on a volumetric 3D display makes it possible for test engineers to observe resource utilization continuously as the mission develops. Quicker turn-around times in the decision process will lead to more efficient use of limited test resources and will increase the information content of the data being collected.
7
Svensson, Martin. "Accelerated Volumetric Next-Best-View Planning in 3D Mapping." Thesis, Linköpings universitet, Datorseende, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-111905.
Full textAbstract:
The Next-Best-View (NBV) problem plays an important part in automatic 3D object reconstruction and exploration applications. This thesis presents a novel approach of ray-casting in Occupancy Grid Maps (OGM) in the context of solving the NBV problem in a 3D-exploration setting. The proposed approach utilizes the structure of an octree-based OGM to perform calculations of potential information gain. The computations are significantly faster than current methods, without decreasing mapping quality. Performance, both in terms of mapping quality, coverage and computational complexity, is experimentally verified through a comparison with existing state-of-the-art methods using high-resolution point cloud data generated using time-of-flight laser range scanners. Current methods for viewpoint ranking focus either heavily on mapping performance or computation speed. The results presented in this thesis indicate that the proposed method is able to achieve a mapping performance similar to the performance-oriented approaches while maintaining the same low computation speed as more approximative methods.
8
Nitschke, Christian. "3D reconstruction : real-time volumetric scene reconstruction from multiple views /." Saarbrücken : VDM Verl. Müller, 2007. http://deposit.d-nb.de/cgi-bin/dokserv?id=2939698&prov=M&dok_var=1&dok_ext=htm.
Full text
9
Robinson, Martin J. "A logical formulation of the 3D reconstruction problem using volumetric framework /." [St. Lucia, Qld.], 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17245.pdf.
Full text
10
Xing, Baoyuan. "Improved 3D Heart Segmentation Using Surface Parameterization for Volumetric Heart Data." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/270.
Full textAbstract:
Imaging modalities such as CT, MRI, and SPECT have had a tremendous impact on diagnosis and treatment planning. These imaging techniques have given doctors the capability to visualize 3D anatomy structures of human body and soft tissues while being non-invasive. Unfortunately, the 3D images produced by these modalities often have boundaries between the organs and soft tissues that are difficult to delineate due to low signal to noise ratios and other factors. Image segmentation is employed as a method for differentiating Regions of Interest in these images by creating artificial contours or boundaries in the images. There are many different techniques for performing segmentation and automating these methods is an active area of research, but currently there are no generalized methods for automatic segmentation due to the complexity of the problem. Therefore hand-segmentation is still widely used in the medical community and is the €œGold standard€� by which all other segmentation methods are measured. However, existing manual segmentation techniques have several drawbacks such as being time consuming, introduce slice interpolation errors when segmenting slice-by-slice, and are generally not reproducible. In this thesis, we present a novel semi-automated method for 3D hand-segmentation that uses mesh extraction and surface parameterization to project several 3D meshes to 2D plane . We hypothesize that allowing the user to better view the relationships between neighboring voxels will aid in delineating Regions of Interest resulting in reduced segmentation time, alleviating slice interpolation artifacts, and be more reproducible.
11
Cho, Jung-Hyun. "SCALABLE VOLUMETRIC THREE-DIMENSIONAL UP-CONVERSION DISPLAY MEDIUM." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3432.
Full textAbstract:
There are many different techniques to display 3D information. However, not many of them are able to provide sufficient depth cues to the observers to sense or feel the images as real three-dimensional objects. Volumetric three-dimensional displays generate images within a real 3D space, so they provide most of the depth cues automatically. This thesis discusses the basic notions required to understand three-dimensional displays. Also discussed are different techniques used to display 3D information and their advantages and disadvantages as well as their current limitations. Several rare-earth doped fluoride crystals that are excited to emit visible light by sequential two photon absorption have been investigated as display medium candidates for static volumetric three dimensional displays. A scalable display medium is suggested to enable large 3D displays. This medium is a dispersion of particles of the rare earth doped fluoride crystals in a refractive index-matched polymer matrix. Detailed experiments are described to prepare such a scalable display medium using a wide variety of polymers. The scattering problem in such a medium was greatly reduced by index-matching the polymer to the crystalline particles. An index-matching condition that optimizes the performance was identified and demonstrated. A potential near-future solution is demonstrated and improvements are suggested.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
12
Flitton, Greg. "Extending computer vision techniques to recognition problems in 3D volumetric baggage imagery." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7993.
Full textAbstract:
We investigate the application of computer vision techniques to rigid object recognition in Computed Tomography (CT) security scans of baggage items. This imagery is of poor resolution and is complex in nature: items of interest can be imaged in any orientation and copious amounts of clutter, noise and artefacts are prevalent. We begin with a novel 3D extension to the seminal SIFT keypoint descriptor that is evaluated through specific instance recognition in the volumetric data. We subsequently compare the performance of the SIFT descriptor against a selection of alternative descriptor methodologies. We demonstrate that the 3D SIFT descriptor is notably outperformed by simpler descriptors which appear to be more suited for use in noise and artefact-prone CT imagery. Rigid object class recognition in 3D volumetric baggage data has received little attention in prior work. We evaluate contrasting techniques between a traditional approach derived from interest point descriptors and a novel technique based on modelling of the primary components of the primate visual cortex. We initially demonstrate class recognition through the implementation of a codebook approach. A variety of aspects relating to codebook generation are investigated (codebook size, assignment method) using a range of feature descriptors. Recognition of a number of object classes is performed and results from this show that the choice of descriptor is a critical aspect. Finally, we present a unique extension to the established standard model of the visual cortex: a volumetric implementation. The visual cortex model comprises a hierarchical structure of alternating simple and complex operations that has demonstrated excellent class recognition results using 2D imagery. We derive 3D extensions to each layer in the hierarchy resulting in class recognition results that signficantly outperform those achieved using the earlier traditional codebook approach. Overall we present several novel solutions to object recognition within 3D CT security images that are supported by strong statistical results.
13
Kitzhofer, Jens. "Volumetric measurements of the transitional backward facing step flow." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2011. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-79718.
Full textAbstract:
The thesis describes state of the art volumetric measurement techniques and applies a 3D measurement technique, 3D Scanning Particle Tracking Velocimetry, to the transitional backward facing step flow. The measurement technique allows the spatial and temporal analysis of coherent structures apparent at the backward facing step. The thesis focusses on the extraction and interaction of coherent flow structures like shear layers or vortical structures.
14
Ochmann, Sebastian Klaus [Verfasser]. "Automatic Reconstruction of Parametric, Volumetric Building Models from 3D Point Clouds / Sebastian Klaus Ochmann." Bonn : Universitäts- und Landesbibliothek Bonn, 2019. http://d-nb.info/1188731599/34.
Full text
15
Iescheck, Andrea Lopes. "Representação e visualização volumétrica de dados espaciais para avaliação de solos." oai:ufpr.br:234189, 2006. http://200.17.209.5:8000/cgi-bin/gw_42_13/chameleon.42.13a?host=localhost%201111%20DEFAULT&sessionid=VTLS&function=CARDSCR&search=KEYWORD&pos=1&u1=12101&t1=234189.
Full textAbstract:
Orientadora : Claudia Robbi SluterCo-orientador : Renato Antonio Dedecek
Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciencias da Terra, Programa de Pós-Graduação em Ciencias Geodésicas. Defesa: Curitiba, 2006
Inclui bibliografia
16
Urs, Radu Dragos. "Non-parametric synthesis of volumetric textures from a 2D sample." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00821886.
Full textAbstract:
This thesis deals with the synthesis of anisotropic volumetric textures from a single 2D observation. We present variants of non parametric and multi-scale algorithms. Their main specificity lies in the fact that the 3D synthesis process relies on the sampling of a single 2D input sample, ensuring consistency in the different views of the 3D texture. Two types of approaches are investigated, both multi-scale and based on markovian hypothesis. The first category brings together a set of algorithms based on fixed-neighbourhood search, adapted from existing algorithms of texture synthesis from multiple 2D sources. The principle is that, starting from a random initialisation, the 3D texture is modified, voxel by voxel, in a deterministic manner, ensuring that the grey level local configurations on orthogonal slices containing the voxel are similar to configurations of the input image. The second category points out an original probabilistic approach which aims at reproducing in the textured volume the interactions between pixels learned in the input image. The learning is done by non-parametric Parzen windowing. Optimization is handled voxel by voxel by a deterministic ICM type algorithm. Several variants are proposed regarding the strategies used for the simultaneous handling of the orthogonal slices containing the voxel. These synthesis methods are first implemented on a set of structured textures of varied regularity and anisotropy. A comparative study and a sensitivity analysis are carried out, highlighting the strengths and the weaknesses of the different algorithms. Finally, they are applied to the simulation of volumetric textures of carbon composite materials, on nanometric scale snapshots obtained by transmission electron microscopy. The proposed experimental benchmark allows to evaluate quantitatively and objectively the performances of the different methods.
17
Rogers, R. Wesley. "Improvements in Optical Trap Displays." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8686.
Full textAbstract:
This thesis improves on the design of the Optical Trap Display (OTD), presented in 2018 [1]. Contributions include: real time animation; single beam, multiparticle suspension, point primitive anisotropic scattering, and virtual image approximation. First, real time animation was demonstrated on the OTD for the first time in full color at up to 30Hz refresh. Second, multi-particle systems allow for scaling of the display by a multiplicative factor, potentially up to orders of magnitude greater than the first OTD. Third, anisotropic scattering of point primitives was shown for individual suspended particles and multiple simultaneously suspended particles. Fourth, virtual images have been previously considered impossible in volumetric displays but by using perspective projections we have shown in simulation and experiment for the first time that an effect similar to a virtual image can be created.
18
Svěchovský, Radek. "Rekonstrukce 3D geometrie na základě diskrétních volumetrických dat." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2013. http://www.nusl.cz/ntk/nusl-236229.
Full textAbstract:
Conversion of discrete volumetric data to boundary representation is quite common operation. Standard approach to resolve this problem is to use well-known Marching cubes algorithm, which although simple and robust, generates low-quality output that requires subsequent post-processing. This master's thesis deals with uncommon algorithms used for isosurface extraction from volumes. The reader will be acquainted with fundamental principles of Hierarchical Iso-Surface Extraction method, that was independently implemented and tested in this work.
19
Samim, Karim, and Sven Thole. "Interaktiv segmentering av volymetrisk data i en 3D-miljö." Thesis, Linköpings universitet, Medie- och Informationsteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-160534.
Full textAbstract:
In this thesis, the goal was to implement a method to do partial segmentation for general 3D volumetric datasets such as mummies, clay figurines or animal bodies. There are different approaches for segmenting volumes, such as automatic methods, semi-automatic methods and interactive methods. However, no automatic algorithm was found that could successfully segment any general 3D volume with high precision. Instead, the chosen approach are segmentation tools which allows the user to quickly and intuitively do partial segmentation from a 3D volume. The tools consist of a interactive 3D brush, a transfer function editor and a semi-automatic flood fill tool which performs region growing in 3D. User studies were carried out in order to evaluate the speed and effectiveness of the segmenting tools compared to the conventional method of segmenting using a stack of 2D images. Based on the user studies the results shows that the proposed method is faster compared to the old method as long as high precision is not required.
20
Kim, Jae-Seung. "Objective image quality assessment for positron emission tomography : planar (2D) and volumetric (3D) human and model observer studies /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/5836.
Full text
21
Perini, Ana Paula. "Software para orientação de neurocirurgia guiada por um transdutor espacial 3D." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-21012008-203347/.
Full textAbstract:
Neurocirurgia guiada por imagem permite ao neurocirurgião navegar dentro do cérebro do paciente, usando imagens pré-operatórias como orientação, através do uso de sistemas de rastreamento, durante o procedimento cirúrgico. Muitos sistemas desenvolvidos para neurocirurgia guiada por imagem, empregam imagens pré-operatórias para fornecer orientação ao cirurgião, durante o procedimento cirúrgico. Seguindo um procedimento de calibração, a posição tridimensional e orientação dos instrumentos cirúrgicos podem ser transmitidas ao computador. Estas informações espaciais são usadas para acessar a região de interesse nas imagens pré-operatórias com a finalidade de apresentá-las ao cirurgião durante o procedimento. Contudo, quando ocorre a craniotomia, o movimento dos tecidos do cérebro pode ser fonte significativa de erro nestes sistemas. A arquitetura implementada neste trabalho visa o desenvolvimento de um sistema que permite planejamento e orientação cirúrgica. Para orientação cirúrgica foi desenvolvido um software que permite extrair fatias do volume de imagens de ressonância magnética (IRM), com orientação fornecida por um transdutor de posição magnético (Polhemus®). As fatias extraídas serão, futuramente, correlacionadas com imagens de ultra-som (IUS) intra-operatórias para detectar e corrigir a deformação do tecido cerebral durante a cirurgia. A ferramenta para navegação pré-cirúrgica foi desenvolvida para fornecer três fatias ortogonais obtidas através do volume de imagens. Na metodologia usada para a implementação do software, foi utilizada a linguagem de programação Python e a biblioteca gráfica Visualization Toolkit (VTK). Os resultados mostraram que o programa de planejamento pré-cirúrgico, gerou uma alta resolução na visualização dos planos ortogonais e oblíquos das IRM, além de ser rápido e interativo. O programa de extrair fatias do volume de IRM permitiu a aplicação de transformações ao volume, com base nos valores de coordenadas fornecidos pelo transdutor de posição.Image guided neurosurgery enables the neurosurgeon to navigate inside the patient\'s brain using pre-operative images as a guide and a tracking system, during surgical procedure. Many image guided neurosurgery implementations employ pre-operative images as a guide to the surgeons throughout surgical procedure. Following a calibration procedure, three-dimensional position and orientation of surgical instruments may be transmitted to computer. The spatial information is used to access an interest region, in the pre-operative images, displaying them to the neurosurgeon during the surgical procedure. However, when a craniotomy is involved, movements of brain tissue can be a significant source of error in these systems. The architecture implemented in this work intends the development of a system to surgical planning and orientation. For surgical orientation, the software developed allows the extraction of slices from the volume of the magnetic resonance images (MRI) with orientation supplied by a magnetic position sensor (Polhemus®). In the future, the extracted slices will be correlated with intra-operative ultrasound images to detect and to correct the deformation of brain tissue during the surgery. Also, a tool for pre-operative navigation was developed, providing three orthogonal planes through the image volume. In the methodology used for the software implementation, the Python programming language and the Visualization Toolkit (VTK) graphics library were used. The results showed that the program of pre-operative navigation had high resolution in the visualization of orthogonal and oblique MRI planes. Furthermore, it was fast and interactive. The program to extract slices of the MRI volume allowed the application of transformations in the volume, using coordinates supplied by the position sensor.
22
Bhagaloo, Visham. "Volumetric modulated Arc Therapy versus 3D conformal radiotherapy in the treatment of locally advanced cervical cancer. A single institution, comparative dosimetric study." Master's thesis, Faculty of Health Sciences, 2021. http://hdl.handle.net/11427/32601.
Full textAbstract:
Background: External Beam Radiotherapy is essential in the management of locally advanced cervical cancer (LACC). Generally, VMAT is thought to achieve higher conformity to the Planned Target Volume (PTV) and better sparing of organs at risk (OAR) when compared to 3D-CRT. This study focused on these principles as it applied to treatment and potential toxicity in the management of LACC. Aim: To compare dosimetric parameters between VMAT and 3D-CRT in the management of LACC. Setting: The study analysed patients treated at Groote Schuur Hospital between May and December 2017. Method: A non-randomized comparative retrospective study. EBRT plans for 3D-CRT and VMAT were generated and data on treatment parameters for PTV D50%, Dmax, Dmean, Conformity Index (CI), Homogeneity Index, Treated Volume (TV), Irradiated Volume (IV) and OAR constraints; femoral heads, bladder, bowel bag, rectum and bone marrow were collected. Results: Of the 45 patients assessed, VMAT showed significantly lower treatment parameter values for CI (1.09 vs 1.49; p< .001) whereas, 3D-CRT showed lower Dmax (48.1Gy vs 49.2Gy; p< .001) and rectum (88.5% vs 96%). A reduced 3D-CRT dose was noted for bladder Dmax (47.4Gy vs 48.3Gy; p< .001). Conclusion: VMAT offered a superior dosimetric option, with better OAR dose sparing and optimal tumour dosimetry.
23
Grandi, Jerônimo Gustavo. "Multidimensional similarity search for 2D-3D medical data correlation and fusion." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/104133.
Full textAbstract:
Imagens da anatomia interna são essenciais para as práticas médicas. Estabelecer correlação entre elas, é um importante procedimento para diagnóstico e tratamento. Nessa dissertação, é proposta uma abordagem para correlacionar dados multidimensionais de mesma modalidade de aquisição baseando-se somente nas informações de intensidade de pixels e voxels. O trabalho foi dividido em duas fases de implementação. Na primeira, foi explorado o problema de similaridade entre imagens médicas usando a perspectiva de análise de qualidade de imagem. Isso levou ao desenvolvimento de uma técnica de dois passos que estabelece um equilíbrio entre a velocidade de processamento e precisão de duas abordagens conhecidas. Avaliou-se a qualidade e aplicabilidade do algoritmo e, na segunda fase, o método foi estendido para analisar similaridade e encontrar a localização de uma imagem arbitrária (2D) em um volume (3D). A solução minimiza o número virtualmente infinito de possíveis orientações transversais e usa otimizações para reduzir a carga de trabalho e entregar resultados precisos. Uma visualização tridimensional volumétrica funde o volume (3D) com a imagem (2D) estabelecendo uma correspondência entre os dados. Uma análise experimental demonstrou que, apesar da complexidade computacional do algoritmo, o uso de amostragem, tanto na imagem quanto no volume, permite alcançar um bom equilíbrio entre desempenho e precisão, mesmo quando realizada com conjuntos de dados de baixa intensidade de gradiente.Images of the inner anatomy are essential for clinical practice. To establish a correlation between them is an important procedure for diagnosis and treatment. In this thesis, we propose an approach to correlate within-modality 2D and 3D data from ordinary acquisition protocols based solely on the pixel/voxel information. The work was divided into two development phases. First, we explored the similarity problem between medical images using the perspective of image quality assessment. It led to the development of a 2-step technique that settles the compromise between processing speed and precision of two known approaches. We evaluated the quality and applicability of the 2-step and, in the second phase, we extended the method to use similarity analysis to, given an arbitrary slice image (2D), find the location of this slice within the volume data (3D). The solution minimizes the virtually infinite number of possible cross section orientations and uses optimizations to reduce the computational workload and output accurate results. The matching is displayed in a volumetric three-dimensional visualization fusing the 3D with the 2D. An experimental analysis demonstrated that despite the computational complexity of the algorithm, the use of severe data sampling allows achieving a great compromise between performance and accuracy even when performed with low gradient intensity datasets.
24
Kubovčík, Tomáš. "Volumetrické efekty akcelerované na GPU." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2017. http://www.nusl.cz/ntk/nusl-363794.
Full textAbstract:
This thesis deals with simulation and rendering of fluid based volumetric effects, especially effect of fire and smoke. Computations are accelerated on graphics card using modern graphics API with motivation to achieve realistic visual results as well as physically correct calculations. Implemented volumetric effects are distributed as dynamic library which allows addition of these effects to existing applications.
25
Yu, Young Sam. "High spatial/spectral resolution X-ray observations and volumetric 3D modeling of superheated plasma in the planetary nebula BD+30°3639 /." Online version of thesis, 2009. http://hdl.handle.net/1850/11193.
Full text
26
Sychra, Tomáš. "Zobrazení 3D scény ve webovém prohlížeči." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2013. http://www.nusl.cz/ntk/nusl-412882.
Full textAbstract:
This thesis discusses possibilities of accelerated 3D scene displaying in a Web browser. In more detail, it deals with WebGL standard and its use in real applications. An application for visualization of volumetric medical data based on JavaScript, WebGL and Three.js library was designed and implemented. Image data are loaded from Google Drive cloud storage. An important part of the application is 3D visualization of the volumetric data based on volume rendering technique called Ray-casting.
27
Boumaaza, Bouharket. "3D seismic attributes analysis and inversions for prospect evaluation and characterization of Cherokee sandstone reservoir in the Wierman field, Ness County, Kansas." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/35510.
Full textAbstract:
Master of ScienceDepartment of Geology
Abdelmoneam Raef
Matthew W. Totten
This work focuses on the use of advanced seismically driven technologies to estimate the distribution of key reservoir properties which mainly includes porosity and hydrocarbon reservoir pay. These reservoir properties were estimated by using a multitude of seismic attributes derived from post-stack high resolution inversions, spectral imaging and volumetric curvature. A pay model of the reservoir in the Wierman field in Ness County, Kansas is proposed. The proposed geological model is validated based on comparison with findings of one blind well. The model will be useful in determining future drilling prospects, which should improve the drilling success over previous efforts, which resulted in only few of the 14 wells in the area being productive. The rock properties that were modeled were porosity and Gamma ray. Water saturation and permeability were considered, but the data needed were not available. Sequential geological modeling approach uses multiple seismic attributes as a building block to estimate in a sequential manner dependent petrophysical properties such as gamma ray, and porosity. The sequential modelling first determines the reservoir property that has the ability to be the primary property controlling most of the other subsequent reservoir properties. In this study, the gamma ray was chosen as the primary reservoir property. Hence, the first geologic model built using neural networks was a volume of gamma ray constrained by all the available seismic attributes. The geological modeling included post-stack seismic data and the five wells with available well logs. The post-stack seismic data was enhanced by spectral whitening to gain as much resolution as possible. Volumetric curvature was then calculated to determine where major faults were located. Several inversions for acoustic impedance were then applied to the post-stack seismic data to gain as much information as possible about the acoustic impedance. Spectral attributes were also extracted from the post-stack seismic data. After the most appropriate gamma ray and porosity models were chosen, pay zone maps were constructed, which were based on the overlap of a certain range of gamma ray values with a certain range of porosity values. These pay zone maps coupled with the porosity and gamma ray models explain the performance of previously drilled wells.
28
Selim, Hossam. "Hybrid non-destructive technique for volumetric defect analysis and reconstruction by remote laser induced ultrasound." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669481.
Full textAbstract:
This PhD thesis is devoted to the design, development and implementation of a non-contact hybrid non-destructive testing (NDT) method applied to the analysis of metallic objects that contain embedded defects or fractures. We propose a hybrid opto-acoustic technique that combines laser generated ultrasound as exciter and ultrasound transducers as receivers. This work envisages a detailed study of the detection and one, two or three-dimensional reconstruction of defects, using the proposed hybrid technique and its application as a remotely controlled non-contact NDT. Our device combines several advantages of both photonic and ultrasonic techniques, while reduces some of the drawbacks of both individual methods. Our method relay on the combination of experimental results with high-resolution signal processing procedures based on different mathematical algorithms. Our basic experimental setup uses a nanosecond pulsed laser at 532nm wavelength that impacts onto the surface of the object under study. The laser pulse is rapidly absorbed into a shallow volume of material and creates a localized thermo-elastic expansion inducing a broadband ultrasound pulse that propagate inside the material. The laser beam scans a selected area of the object surface, being remotely controlled by means of a programmable XY scanner. For each excitation point, the ultrasound waves propagate through the object are reflected or scattered by material 3D defects. They are detected by ultrasound transducers and recorded with a PC data-acquisition system for a further process and analysis. As a first step, the time of flight analysis provides enough data for the location and size of the defect in 1D view. The detection capabilities of internal defects in a metallic sample are studied by means of wavelet transform, chosen due to its multi-resolution time-frequency characteristics. A novel algorithm using a density-based spatial clustering is applied to the resulting time frequency maps to estimate the defect’s position. For the 2D visualization and reconstruction of the defects we extended the signal analysis using the synthetic aperture focusing technique (SAFT). We implement a novel 2D apodization window filtering applied along with the SAFT, and we show it removes undesired effects of the side lobes and wide-angle reflections of ultrasound waves, enhancing the reconstructed image of the defect. We move then towards the 3D analysis and reconstruction of defects and in this case we achieve and implement a fully non-contact and automatized experimental configuration allowing the scan areas on different object’s faces. The defect details are recorded from different angles/perspectives and a complete 3D reconstruction is achieved. Finally, we show our results on a complementary topic related to a particular case of the ultrasound propagation in solids. We were concerned on the physical understanding of the propagation and diffraction of ultrasound waves in solid materials from the first moment. The control of the diffraction pattern in solids, using an ultrasonic lens, would help focus/collimate the ultrasound reducing echoes and boundary reflections, resulting in a further improve NDT process. Phononic crystals have been used to regulate the diffraction and frequency response of ultrasonic waves traveling in fluids. However, they were much less studied in solid materials due to the difficulty of building the crystal and to high coupling losses. We perform detailed numerical simulations of the ultrasound propagation in a solid phononic crystal and we show focusing and the self-collimation effects. We further extend our analysis and couple our phononic crystal lens to a solid under study, showing that the diffraction control is preserved inside the target solid object trough the coupling material.Esta tesis doctoral versa sobre el diseño, estudio e implementación de un método híbrido, sin contacto, de ensayos no destructivos (NDT, non-destructive testing) para el análisis de objetos metálicos que contienen defectos o fracturas internas. Proponemos una técnica híbrida opto-acústica que combina ultrasonidos generados por impacto láser como excitador y transductores de ultrasonidos como receptores. El trabajo plantea un estudio detallado de la detección y reconstrucción en 1D, 2D y 3D de defectos presentes en un objeto metálico, usando la técnica híbrida de NDT sin contacto y controlado remotamente. Nuestro dispositivo presenta varias ventajas de las técnicas fotónicas y de ultrasonidos, reduciendo al mismo tiempo algunos inconvenientes de dichos métodos tomados por separado. Nuestro método combina resultados experimentales con simulaciones numéricas basadas en el procesado de señal de alta resolución. El montaje experimental consiste en un láser pulsado de ns a una longitud de onda de 532 nm, que impacta sobre la superficie del objeto. El pulso láser se absorbe, creando una expansión termoelástica localizada que induce un pulso de ultrasonidos de banda ancha que se propaga en el material. El láser, controlado remotamente, realiza un barrido sobre un área seleccionada de la superficie del objeto. Por cada punto de excitación, el ultrasonido se propaga a través del objeto y se refleja o dispersa en los defectos del material. Dichas ondas se detectan mediante transductores y se registran en un sistema de adquisición de datos para su ulterior procesado. En un primer paso, mediante el análisis del tiempo de vuelo, podemos localizar y determinar el tamaño del defecto en una vista 1D. Las capacidades de detección de defectos internos en una muestra metálica se estudian también mediante transformación wavelet debido a sus características de multi-resolución en tiempo y frecuencia. Se aplica un algoritmo novedoso de agrupamiento (clustering) espacial y se usan los mapas resultantes de tiempo y frecuencia para estimar la posición del defecto. Para la visualización 2D de los defectos ampliamos el análisis de la señal utilizando la técnica de focalización por apertura sintética (SAFT, synthetic aperture focusing technique). Implementamos un novedoso filtro de apodización 2D, juntamente con la técnica SAFT, y demostramos que elimina efectos no deseados, mejorando la resolución de la imagen reconstruida del defecto. El siguiente paso es un análisis y reconstrucción 3D. En este caso conseguimos una configuración experimental totalmente automatizada y sin contacto, permitiendo áreas de barrido sobre diferentes caras de un objeto. Los detalles de los defectos se registran desde diferentes ángulos, consiguiéndose una completa reconstrucción 3D. Finalmente, mostramos nuestros resultados en un tema complementario, relacionado con un caso particular de propagación de ultrasonidos en sólidos. Desde un primer momento, quisimos tener una comprensión física de la propagación y difracción de ondas de ultrasonidos en materiales sólidos. El control de los patrones de difracción en sólidos, mediante el uso de lentes ultrasónicas, ayudaría a la focalización/colimación del ultrasonido, reduciendo ecos y reflexiones en la superficie de contorno, mejorando del proceso de análisis NDT. Los cristales fonónicos se usan para regular la difracción y la respuesta en frecuencia de ondas de ultrasonido que se propagan en fluidos. No obstante, dichas estructuras se han estudiado mucho menos en materiales sólidos. Hemos realizado detalladas simulaciones numéricas de la propagación de ultrasonidos en un cristal fonónico sólido y hemos demostrado efectos de focalización y autocolimación. Finalmente hemos acoplado nuestra lente de cristal fonónico al sólido objeto de estudio, demostrando que el control de la difracción se conserva en el interior de dicho objeto a través del material de acoplamiento. Finalmente, proporcionamos una conclusión general sobre el trabajo declarado en esta tesis y un plan de trabajo futuro donde esta investigación puede extenderse y expandirse aún más a aplicaciones industriales en colaboración con el mercado de producción
29
Azizian, Kalkhoran Mohammad. "Design and development of a universal handheld probe for optoacoustic-ultrasonic 3D imaging." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI027/document.
Full textAbstract:
La présente dissertation est principalement consacrée à la conception et à la caractérisation d’une sonde universelle pour l’imagerie volumétrique ultrasons-optoacoustique et le développement d’un algorithme de reconstruction adapté aux exigences physiques pour la conception du système. Les traits distinctifs de cette dissertation sont l’introduction d’une nouvelle géométrie pour les sondes manuelles ultrasons-optoacoustique et des évaluations systématiques basées sur des méthodes de pré-reconstruction et post-reconstruction. Pour éviter l’interprétation biaisée, une évaluation capable d’évaluer le potentiel de la sonde doit être faite. Les caractéristiques mentionnées établissent un cadre pour l’évaluation des performances du système d’imagerie d’une manière précise. En outre, elle permet d’optimiser les performances suivant l’objectif fixé. Ainsi, deux algorithmes de reconstruction anticipée ont été élaborés pour la conception du système OPUS (optoacoustique ultrasons) capables de produire des images avec un contraste et une résolution homogènes sur tout le volume d’intérêt. L’intérêt d’avoir de tels algorithmes est principalement dû au fait que l’analyse des données médicales est souvent faite dans des conditions difficiles, car on est face au bruit, au faible contraste, aux projections limités et à des transformations indésirables opérées par les systèmes d’acquisition. Cette thèse montre, aussi, comment les artefacts de reconstruction peuvent être réduits en compensant les propriétés d’ouverture et en atténuant les artefacts dus à l’échantillonnage angulaire parcimonieux. Afin de transférer cette méthodologie à la clinique et de valider les résultats théoriques, une plate-forme d’imagerie expérimentale a été développée. En utilisant le système de mesure développé, l’évolution d’une nouvelle géométrie annulaire parcimonieuse et sa dynamique ont été étudiées et une preuve de concept a été démontrée à travers des mesures expérimentales dans le but d’évaluer les progrès réalisésWhen the interest is in multiscale and multipurpose imaging, there exists such a will in integrating multi-modalilties into a synergistic paradigm in order to leverage the diagnostic values of the interrogating agents. Employing multiple wavelengths radiation, optoacoustic imaging benefits from the optical contrast to specifically resolve molecular structure of tissue in a non-invasive manner. Hybridizing optoacoustic and ultrasound imaging comes with the promises of delivering the complementary morphological, functional and metabolic information of the tissue. This dissertation is mainly devoted to the design and characterization of a hybridized universal handheld probe for optoacoustic ultrasound volumetric imaging and developing adaptive reconstruction algorithms toward the physical requirements of the designed system. The distinguishing features of this dissertation are the introduction of a new geometry for optoacoustic ultrasonic handheld probe and systematic assessments based on pre and post reconstruction methods. To avoid the biased interpretation, a de facto performance assessment being capable of evaluating the potentials of the designed probe in an unbiased manner must be practiced. The aforementioned features establish a framework for characterization of the imaging system performance in an accurate manner. Moreover, it allows further task performance optimization as well. Correspondingly, two advanced reconstruction algorithms have been elaborated towards the requirement of the designed optoacoustic-ultrasound (OPUS) imaging system in order to maximize its ability to produce images with homogeneous contrast and resolution over the entire volume of interest. This interest is mainly due to the fact that the medical data analysis pipeline is often carried out in challenging conditions, since one has to deal with noise, low contrast, limited projections and undesirable transformations operated by the acquisition system. The presented thesis shows how reconstruction artifacts can be reduced by compensating for the detecting aperture properties and alleviate artifacts due to sparse angular sampling. In pursuit of transferring this methodology to clinic and validating the theoretical results, a synthetic imaging platform was developed. Using the measurement system, the evolution of a novel sparse annular geometry and its dynamics has been investigated and a proof of concept was demonstrated via experimental measurement with the intention of benchmarking progress
30
Matte, Martin, and Daniel Rangne. "Drones in Civil Engineering Projects : Areas of Application With a Focus On Photogrammetry." Thesis, KTH, Byggteknik och design, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302547.
Full textAbstract:
Drone technology has changed the way people work in construction and civil engineering activities. The aim of this report is to investigate how drones can and should be used in the best possible way. Autodesk ReCap Photo and Agisoft Metashape Professional are the two photogrammetry software programs that have been compared. The results show that Metashape can create more accurate maps and 3D models, but requires more powerful hardware to operate and takes longer time to learn. ReCap Photo is easier to handle but produces maps and 3D models that are slightly less accurate. Interviews have been conducted with experts, and they highlight that the EU regulations governing drone activity pose a great challenge for optimal usage of drones in construction and civil engineering. Assuming that drones are operated in a safe manner, they unlock significant potential gains with respect to environment, work environment and economy. Some of the most important areas of application are volumetric measurements of gravel, inspections in high altitude environments and regular mapping of construction sites.Drönartekniken har förändrat arbetssätten i bygg- och anläggningsverksamhet. Denna rapport syftar till att undersöka hur drönare kan och bör användas på bästa sätt. Autodesk ReCap Photo och Agisoft Metashape Professional är de två fotogrammetriprogramvaror som har jämförts. Resultaten visar att Metashape kan skapa mer noggranna kartor och 3D-modeller, men kräver kraftigare hårdvara och tar längre tid att lära sig. ReCap Photo är mer lätthanterligt men ger inte lika noggranna kartor och 3D-modeller. Intervjuer med sakkunniga har genomförts, och av dessa framgår att de EU-gemensamma lagarna som reglerar drönarflygning utgör en stor utmaning för att kunna använda drönarna optimalt i bygg- och anläggningsverksamhet. Förutsatt att drönare flygs på ett säkert sätt, banar de vägen för stora potentiella vinster med avseende på miljö, arbetsmiljö och ekonomi. Några av de viktigaste användningsområdena är volymberäkning av grushögar, inspektioner på hög höjd och löpande kartering av byggarbetsplatser.
31
Albuquerque, Marco Antonio Portela. "Avaliação volumétrica de defeitos ósseos em fissuras de rebordo alveolar e palato duro por meio da 3D-TC multislice e feixe cônico." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/23/23139/tde-22122010-120700/.
Full textAbstract:
As fissuras de rebordo alveolar e palato duro estão entre as malformações mais frequentes do corpo humano, podendo causar extensas deformidades ósseas faciais, com implicações biopsíquico-sociais marcantes. A avaliação da extensão desses defeitos ósseos, através de exames por imagem, tem sido feita com o objetivo de diagnosticar e planejar a terapêutica reabilitadora dos pacientes. O presente estudo tem por objetivo desenvolver uma metodologia de pós-processamento de imagens tomográficas para avaliação volumétrica de defeitos ósseos confeccionados em palato duro e rebordo alveolar de crânios macerados, mimetizando fissuras trans-forâmens unilaterais, e verificar a aplicabilidade clínica do Tomógrafo Computadorizado espiral Multislice e do tomógrafo computadorizado por feixe cônico na análise desses defeitos. Para tanto, nove crânios provenientes da Faculdade Cathedral, da cidade de Boa Vista- RR, foram escaneados em um Tomógrafo Computadorizado Multislice pertencente ao Hospital Geral de Roraima e em um tomógrafo computadorizado por feixe cônico de uma clínica privada, na cidade de Fortaleza-CE. As imagens foram, posteriormente, encaminhadas para análise ao Laboratório em Terceira Dimensão(LAB-3D) da Faculdade de Odontologia da USP, utilizando-se uma estação de trabalho independente e aplicando-se programas específicos de computação gráfica. Todas as imagens foram analisadas por dois examinadores, individualmente e em tempos distintos, por duas vezes, com o objetivo de processarmos análises intra e interexaminadores. Para a análise da metodologia de processamento de imagens, comparamos os resultados obtidos pelo Tomógrafo multislice utilizando crânios sem cera e com cera de modelagem número 07, na região do defeito ósseo, para auxiliar no seu delineamento, durante o pós-processamento das imagens tomográficas. Foram também avaliados os resultados volumétricos obtidos nos dois tipos de tomógrafos,com o objetivo de verificar a aplicabilidade dessas tecnologias na avaliação volumétrica dos defeitos ósseos fissurais e de comparar os resultados obtidos por cada uma delas. Todos os resultados foram comparados com os valores estabelecidos pelo padrão - ouro de nossa análise, que foram obtidos através do princípio de Arquimedes de deslocamento de água dos modelos de cera que foram utilizados. Os resultados estatísticos demonstraram que a metodologia de processamento das imagens tomográficas apresentou uma eficácia bastante elevada (p=0,995), sendo considerada eficiente na avaliação volumétrica de defeitos ósseos fissurais. Com relação aos tomógrafos utilizados, observamos que tanto o multislice como o por feixe cônico também apresentaram resultados satisfatórios, apresentando grande confiabilidade para o estudo do volume dos defeitos ósseos fissurais (p=0,997 e p=0,981, respectivamente), não havendo diferença nos resultados encontrados por eles. As análises intra e interobservadores nos dois tipos de tomógrafos não demonstraram diferença estatisticamente significativa. Os resultados evidenciaram que, independente do tipo de tomógrafo utilizado e do avaliador, as medidas obtidas são estatisticamente iguais às conseguidas pelo padrão-ouro de nossa análise. A aplicabilidade clínica de nossa pesquisa demonstrou ser direta e imediata, sendo importante no processo diagnóstico/terapêutico dos pacientes portadores de fissuras de rebordo alveolar e palato duro.Oral clefts are one of the most frequent malformations of the human body, causing extensive facial bone deformities, compromising biological, psychic and social the individuals affected. Multislice CT and CBCT have been used to assess the volume of bone defect with the goal of diagnosis and rehabilitative therapy planning of the patients. The aim of this study were to develop a methodology for post-processing of tomographic images for volumetric assessment of bone defects made in the hard palate and alveolar ridge of dry skulls, mimicking unilateral trans-foramen clefts; and to determine the clinical applicability of multislice spiral computed tomography, and cone beam computed tomography in the analysis of these defects. Nine dry skulls from the Cathedral College in Boa Vista-RR were scanned on a multislice CT scanner at the Hospital Geral de Roraima and a cone beam computed tomography in a private clinic in Fortaleza-CE. The images were sent for analysis at Three Dimensional Laboratory (LAD-3D) of the Dentistry School, São Paulo University, using an independent workstation and implementing specific computer graphics programs. All images were analyzed by two examiners at different times and twice to proceed the intra and inter-examiners analysis. For analysis the methodology of image processing, we compared the results obtained by multislice CT using skulls with and without wax model in the region of bone defect. It was also analyzed the same images in both types of CT scanners in order to determine the applicability of these radiographic techniques in assessing volume of the clefts and to compare the results. All results were compared with the gold standard of our analysis, which was obtained by Archimedes principle of water displacement of wax models. The statistical results showed that the post processing methodology of tomographic images showed a high efficiency (p = 0.995) and was considered an efficient method for volumetric assessment of fissure bone defects. It was also observed that both multislice CT and cone beam CT showed excellent results with high reliability in the study of the volume of bone defects (p = 0.997 and p = 0.981, respectively), with no difference in performance between them. Analysis of intra-and inter-observer in the two types of CT scanners showed no statistically significant difference. The results demonstrate that independent of the type of CT scanner and the appraiser, the measurements are statistically equal to the gold standard obtained by our analysis. The clinical applicability of our research has shown to be immediate and direct, and it is important for the diagnostic and therapeutic process of patients with oral cleft.
32
López, Picazo Mirella. "3D subject-specific shape and density modeling of the lumbar spine from 2D DXA images for osteoporosis assessment." Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/666513.
Full textAbstract:
Osteoporosis is the most common bone disease, with a significant morbidity and mortality caused by the increase of bone fragility and susceptibility to fracture. Dual Energy X-ray Absorptiometry (DXA) is the gold standard technique for osteoporosis and fracture risk evaluation at the spine. However, the standard analysis of DXA images only provides 2D measurements and does not differentiate between bone compartments; neither specifically assess bone density in the vertebral body, which is where most of the osteoporotic fractures occur. Quantitative Computed Tomography (QCT) is an alternative technique that overcomes limitations of DXA-based diagnosis. However, due to the high cost and radiation dose, QCT is not used for osteoporosis management. In this thesis, a method providing a 3D subject-specific shape and density estimation of the lumbar spine from a single anteroposterior DXA image is proposed. The method is based on a 3D statistical shape and density model built from a training set of QCT scans. The 3D subject-specific shape and density estimation is obtained by registering and fitting the statistical model onto the DXA image. Cortical and trabecular bone compartments are segmented using a model-based algorithm. 3D measurements are performed at different vertebral regions and bone compartments. The accuracy of the proposed methods is evaluated by comparing DXA-derived to QCT-derived 3D measurements. Two case-control studies are also performed: a retrospective study evaluating the ability of DXA-derived 3D measurements at lumbar spine to discriminate between osteoporosis-related vertebral fractures and control groups; and a study evaluating the association between DXA-derived 3D measurements at lumbar spine and osteoporosis-related hip fractures. In both studies, stronger associations are found between osteoporosis-related fractures and DXA-derived 3D measurements compared to standard 2D measurements. The technology developed within this thesis offers an insightful 3D analysis of the lumbar spine, which could potentially improve osteoporosis and fracture risk assessment in patients who had a standard DXA scan of the lumbar spine without any additional examination.La osteoporosis es la enfermedad ósea más común, con una morbilidad y mortalidad significativas causadas por el aumento de la fragilidad ósea y la susceptibilidad a las fracturas. La absorciometría de rayos X de energía dual (DXA, por sus siglas en inglés) es la técnica de referencia para la evaluación de la osteoporosis y del riesgo de fracturas en la columna vertebral. Sin embargo, el análisis estándar de las imágenes DXA solo proporciona mediciones 2D y no diferencia entre los compartimentos óseos; tampoco evalúa la densidad ósea en el cuerpo vertebral, que es donde se producen la mayoría de las fracturas osteoporóticas. La tomografía computarizada cuantitativa (QCT, por sus siglas en inglés) es una técnica alternativa que supera las limitaciones del diagnóstico basado en DXA. Sin embargo, debido al alto costo y la dosis de radiación, la QCT no se usa para el diagnóstico de la osteoporosis. En esta tesis, se propone un método que proporciona una estimación personalizada de la forma 3D y la densidad de la columna vertebral en la zona lumbar a partir de una única imagen DXA anteroposterior. El método se basa en un modelo estadístico 3D de forma y densidad creado a partir de un conjunto de entrenamiento de exploraciones QCT. La estimación 3D personalizada de forma y densidad se obtiene al registrar y ajustar el modelo estadístico con la imagen DXA. Se segmentan los compartimentos óseos corticales y trabeculares utilizando un algoritmo basado en modelos. Se realizan mediciones 3D en diferentes regiones vertebrales y compartimentos óseos. La precisión de los métodos propuestos se evalúa comparando las mediciones 3D derivadas de DXA con las derivadas de QCT. También se realizan dos estudios de casos y controles: un estudio retrospectivo que evalúa la capacidad de las mediciones 3D derivadas de DXA en la columna lumbar para discriminar entre sujetos con fracturas vertebrales relacionadas con la osteoporosis y sujetos control; y un estudio que evalúa la asociación entre las mediciones 3D derivadas de DXA en la columna lumbar y las fracturas de cadera relacionadas con la osteoporosis. En ambos estudios, se encuentran asociaciones más fuertes entre las fracturas relacionadas con la osteoporosis y las mediciones 3D derivadas de DXA en comparación con las mediciones estándar 2D. La tecnología desarrollada dentro de esta tesis ofrece un análisis en 3D de la columna lumbar, que podría mejorar la evaluación de la osteoporosis y el riesgo de fractura en pacientes que se sometieron a una exploración DXA estándar de la columna lumbar sin ningún examen adicional.
33
Strandstedt, Jonas. "Multi-Volume Rendering in OpenSpace Using A-Buffers for Space Weather Visualizations." Thesis, Linköpings universitet, Medie- och Informationsteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-137673.
Full textAbstract:
The work described in this thesis is part of the initial development of the open-source visualization software OpenSpace, a collaborative project between Linköping University (LiU), the National Aeronautics and Space Administration (NASA) and the American Museum of Natural History (AMNH). The report covers the background and implementation of a rendering system that enables OpenSpace to interactively visualize multiple overlapping space weather events. The system works much like a Deferred Renderer by rendering all objects once and then resolves the final image in a second rendering step. To render a mix of opaque and translucent objects and volumes simultaneously, order-independent transparency solutions are implemented. Performance is compared against traditional methods and possible improvements are discussed. The implemented rendering system is currently powering the OpenSpace visualizations, this gives scientists an interactive tool for studying multiple space weather events, education and public outreach.
34
Joshi, Vinay Joshi. "ELECTRO-OPTICAL AND FLEXOELECTRO-OPTICAL PROPERTIES ENHANCED BY BIMESOGEN-DOPED CHIRAL NEMATIC LIQUID CRYSTALS." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1543053053654711.
Full text
35
Chiu, Siu-hau, and 招兆厚. "A search for optimal radiation therapy technique for lung tumours stereotactic body radiation therapy (SBRT) : dosimetric comparison of 3D conformal radiotherapy, static gantry intensity modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) with flattening filter (FF) or flattening filter-free (FFF) beams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196549.
Full textAbstract:
Materials/Methods:
Ten patients who underwent thoracic SBRT with primary stage I (T1/2N0) lung cancer or oligometastatic lung lesion, with PTV diameter ≤ 5cm were selected and were immobilized with Easyfoam or Vac-Lock. Planned/treated with inspiratory breath-hold (25 seconds, 70 to 80% of vital capacity) assisted with Active Breathing Control (ABC). Four treatment plans: non-coplanar 3DCRT, coplanar static gantry IMRT, coplanar VMAT (FF) and VMAT (FFF) were generated. Field arrangements, either static fields or partial arcs (duration=20 sec) were used to avoid direct beam entry to contralateral lung. All plans were compared in terms of dosimetric performance included dose to PTV or organs at risk (OAR), high/low dose spillage, integral dose (body and lungs), dose delivery efficiency (MU/Gy) and estimated beam-on time (BOT) with reference to the RTOG 0813 protocol.
Results:
All plans complied with RTOG 0813 protocol. VMAT (FF/ FFF) techniques improved target coverage and dose conformity, with the highest conformity number (CN > 0.91), compared to IMRT (0.88) and 3DCRT (0.85). The control of high dose spillage (NT>105% and CI) for IMRT (3.04% and 1.08) and VMAT (FF/ FFF) (1.08/ 1.06% and 1.03/ 1.04) techniques were comparable (p > 0.05) and significantly better than 3DCRT (4.22% and 1.11, p < 0.005) technique. In addition, VMAT (FF/ FFF) techniques performed the best in controlling low dose spillage (D2cm and R50%) compared with IMRT (reduction: 4.7%, p=0.036 and >5.9%, p = 0.009) and 3DCRT (reduction: > 16.3%, p < 0.001 and > 10%, p = 0.002). Benefits of rapid and isotropic dose fall-off were shown from superior tissue sparing (reduction ranges from 3.2% up to 67%) of ipsilateral brachial plexus, skin (0-5mm), great vessels and ribs. Also lung V10, V12.5, esophagus and heart tend to receive lower dose with VMAT technique. The relatively lower integral dose to whole body (> 3Gy∙L reduction, p < 0.013) and ipsilateral lung (0.65Gy∙L reduction, p = 0.025) compared with 3DCRT, were associated with lower risk of radiation induced cancers. The MU/Gy and BOT were substantial lower for VMAT (FF) (22.4% and 32.4%) compared with IMRT. Apart from higher (7%) maximum skin dose, dosimetric performance for VMAT (FFF) was comparable with VMAT (FF), with advantages of further reduction of MU/Gy (1.8% lesser), partial arc numbers (from 12-14 arcs down to 8 arcs) and BOT (35% shortened), owing to the increased dose output with flattening filter removal.
Conclusions:
VMAT (FF and FFF) plans maintained IMRT equivalent plan qualities, simultaneously enhanced the delivery efficiency with shortened BOT. VMAT (FFF) further reduced the required arcs number and BOT, significantly minimized the intra-fraction motions and more tolerable to patient with long SBRT treatment duration.published_or_final_version
Medicine
Master
Master of Medical Sciences
36
Kang, Chi Won. "Enhanced 3-Dimensional Carbon Nanotube Based Anodes for Li-ion Battery Applications." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/955.
Full textAbstract:
A prototype 3-dimensional (3D) anode, based on multiwall carbon nanotubes (MWCNTs), for Li-ion batteries (LIBs), with potential use in Electric Vehicles (EVs) was investigated. The unique 3D design of the anode allowed much higher areal mass density of MWCNTs as active materials, resulting in more amount of Li+ ion intake, compared to that of a conventional 2D counterpart. Furthermore, 3D amorphous Si/MWCNTs hybrid structure offered enhancement in electrochemical response (specific capacity 549 mAhg-1). Also, an anode stack was fabricated to further increase the areal or volumetric mass density of MWCNTs. An areal mass density of the anode stack 34.9 mg/cm2 was attained, which is 1,342% higher than the value for a single layer 2.6 mg/cm2. Furthermore, the binder-assisted and hot-pressed anode stack yielded the average reversible, stable gravimetric and volumetric specific capacities of 213 mAhg-1 and 265 mAh/cm3, respectively (at 0.5C). Moreover, a large-scale patterned novel flexible 3D MWCNTs-graphene-polyethylene terephthalate (PET) anode structure was prepared. It generated a reversible specific capacity of 153 mAhg-1 at 0.17C and cycling stability of 130 mAhg-1 up to 50 cycles at 1.7C.
37
Chromý, Adam. "Multispektrální 3D skenování s vysokým rozlišením a jeho aplikace v medicíně." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-364604.
Full textAbstract:
Termovizní zobrazování i 3D skenování jsou v současné době rychle se rozvíjející technologie. Obě technologie mají mnoho výhod, které by mohly být užitečné v medicíně. Jejich datová fúze přináší ještě více nových diagnostických informací, než kdyby byly použity samostatně. Cílem této práce je vývoj multispektrálního 3D skenovacího systému založeného na novém způsobu snímání pomocí robotického manipulátoru vybaveného laserovým snímačem, teplotní kamerou a barevnou kamerou. Navržené řešení přináší jak flexibilitu, tak přesnost. Tento systém skenování je dále využit v klinických aplikacích, aby byly ověřeny jeho schopnosti a ukázány přínosy nad rámec současného stavu techniky.
38
Sand, Victor. "Dynamic Visualization of Space Weather Simulation Data." Thesis, Linköpings universitet, Medie- och Informationsteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-112092.
Full textAbstract:
The work described in this thesis is part of the Open Space project, a collaboration between Linköping University, NASA and the American Museum of Natural History. The long-term goal of Open Space is a multi-purpose, open-source scientific visualization software. The thesis covers the research and implementation of a pipeline for preparing and rendering volumetric data. The developed pipeline consists of three stages: A data formatting stage which takes data from various sources and prepares it for the rest of the pipeline, a pre-processing stage which builds a tree structure of of the raw data, and finally an interactive rendering stage which draws a volume using ray-casting. The pipeline is a fully working proof-of-concept for future development of Open Space, and can be used as-is to render space weather data using a combination of suitable data structures and an efficient data transfer pipeline. Many concepts and ideas from this work can be utilized in the larger-scale software project.
39
Dietrich, Carlos Augusto. "Visualização interativa e manipulação de imagens 3D em tempo real usando métodos baseados na GPU." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2004. http://hdl.handle.net/10183/6513.
Full textAbstract:
Este trabalho apresenta um conjunto de ferramentas que exploram as capacidades recentes das placas gráficas de computadores pessoais para prover a visualização e a interação com volumes de dados. O objetivo é oferecer ao usuário ferramentas que permitam a remoção interativa de partes não relevantes do volume. Assim, o usuário é capaz de selecionar um volume de interesse, o que pode tanto facilitar a compreensão da sua estrutura quanto a sua relação com os volumes circundantes. A técnica de visualização direta de volumes através do mapeamento de texturas é explorada para desenvolver estas ferramentas. O controle programável dos cálculos realizados pelo hardware gráfico para gerar a aparência de cada pixel na tela é usado para resolver a visibilidade de cada ponto do volume em tempo real. As ferramentas propostas permitem a modificação da visibilidade de cada ponto dentro do hardware gráfico, estendendo o benefício da visualização acelerada por hardware. Três ferramentas de interação são propostas: uma ferramenta de recorte planar que permite a seleção de um volume de interesse convexo; uma ferramenta do tipo “borracha”, para eliminar partes não relevantes da imagem; e uma ferramenta do tipo “escavadeira”, para remover camadas do volume Estas ferramentas exploram partes distintas do fluxo de visualização por texturas, onde é possível tomar a decisão sobre a visibilidade de cada ponto do volume. Cada ferramenta vem para resolver uma deficiência da ferramenta anterior. Com o recorte planar, o usuário aproxima grosseiramente o volume de interesse; com a borracha, ele refina o volume selecionado que, finalmente, é terminado com a escavadeira. Para aplicar as ferramentas propostas ao volume visualizado, são usadas técnicas de interação conhecidas, comuns nos sistemas de visualização 2D. Isto permite minimizar os esforços do usuário no treinamento do uso das ferramentas. Finalmente, são ilustradas as aplicações potenciais das ferramentas propostas para o estudo da anatomia do fígado humano. Nestas aplicações foi possível identificar algumas necessidades do usuário na visualização interativa de conjuntos de dados médicos. A partir destas observações, são propostas também novas ferramentas de interação, baseadas em modificações nas ferramentas propostas.
40
Heisel, Cyprien. "Conception et réalisation, par fabrication additive, de matériaux cellulaires architecturés." Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0046/document.
Full textAbstract:
La démarche « matériaux numériques », développée au CEA Le Ripaut, consiste à optimiser numériquement une structure, à l’aide de codes de calcul permettant de réaliser des expériences numériques, afin de répondre le plus précisément possible à un cahier des charges. La mise en œuvre de ces structures optimisées, aux formes pouvant être complexes, n’est parfois pas réalisable avec les procédés de fabrication actuels. Cependant, la progression rapide de l’impression 3D semble maintenant pouvoir concrétiser cette démarche. Le but de cette thèse est d’étudier cette faisabilité de fabrication, à travers une application concrète : l’optimisation des récepteurs volumétriques des Centrales Solaires Thermodynamiques (CST).Actuellement, la conception de ces récepteurs en Carbure de Silicium (SiC) est restreinte par les techniques existantes de fabrication, et leurs morphologies se limitent donc principalement à des mousses ou des canaux parallèles. Or, ce type de structure ne permet pas d’exploiter tout le caractère 3D proposé par les récepteurs, en raison notamment d’une absorption trop hétérogène du rayonnement solaire dans le volume. Dans ce travail de thèse, afin de rechercher la répartition de l’absorption la plus homogène possible dans l’ensemble du volume, de nombreuses structures aux formes variées sont générées virtuellement. Une simulation de l’éclairement solaire reçu est réalisée sur l’ensemble de ces structures, grâce à un code de calcul développé spécialement pour cette application, permettant ainsi d’en retenir trois répondants au mieux aux critères du cahier des charges. Ces structures potentiellement optimisées ont ensuite été fabriquées en SiC par impression 3D, par un procédé de projection de liant sur lit de poudre. Elles ont été ensuite testées sur un banc d’essai expérimental du laboratoire PROMES, reproduisant les conditions d’une CST. Les résultats ont montrés que ces structures, aux formes totalement différentes de mousses ou de canaux parallèles, sont capables de produire au maximum de l’air à 860°C en sortie de récepteur, et avec des rendements énergétiques proches de 0,65. Enfin, un code de calcul thermique couplé conducto-radiatif, amélioré durant ce travail, a permis d’analyser ces résultats expérimentaux et servira pour les futurs travaux d’optimisation de la géométrie d’un récepteurThe "numerical materials" approach, developed at CEA Le Ripaut, consists to numerically optimize a structure, by using calculation codes that allow to realize numerical experiments, in order to answer, as precisely as possible, to a set of specifications. The manufacturing of these optimized structures, whose shapes can be complex, is sometimes not feasible with current manufacturing processes. However, the rapid progress of 3D printing now seems to be able to concretize this approach. The aim of this thesis is to study this manufacturing feasibility, through a concrete application: the optimization of the volumetric receivers of Concentrated Solar Power Plants (CSP). Currently, the design of these silicon carbide (SiC) receptors is restricted by the existing manufacturing techniques, and their morphologies are therefore mainly limited to foams or parallel channels. However, this type of structure does not allow to exploit all the 3D character proposed by the receivers, due in particular to a heterogeneous absorption of solar radiation in the volume. In this work, in order to find the distribution of the most homogeneous absorption possible in the whole volume, many structures with various shapes are generated virtually. A simulation of the solar irradiance received is carried out on all these structures, thanks to a calculation code developed especially for this application, thus allowing to choose three of them, respondents at best to the criteria of the specifications. These potentially optimized structures were then manufactured in SiC by 3D printing, by a binder jetting process. They were then tested on an experimental test bench of the PROMES laboratory, reproducing the conditions of a CSP. Results showed that these structures, where their shapes are totally different from foams or parallel channels, are able to produce a maximum air temperature of 860°C at the output of the receiver, and with efficiencies close to 0.65. Finally, a conducto-radiative coupled thermal computational code, improved during this work, made it possible to analyze these experimental results and will be used for the future work of optimization of the geometry of a receiver
41
Faller, Jonas [Verfasser]. "Entwicklung und Einsatz eines pulsatilen Echophantoms für die Validierung der Volumetrie mittels Realtime-3D-Echokardiographie / Jonas Faller." Bonn : Universitäts- und Landesbibliothek Bonn, 2019. http://d-nb.info/119900555X/34.
Full text
42
Lima, Rodrigo Freitas. "Reconstrução em 3D de imagens DICOM cranio-facial com determinação de volumetria de muco nos seios paranasais." Universidade Presbiteriana Mackenzie, 2015. http://tede.mackenzie.br/jspui/handle/tede/1465.
Full textAbstract:
Made available in DSpace on 2016-03-15T19:37:58Z (GMT). No. of bitstreams: 1
RODRIGO FREITAS LIMA.pdf: 13768169 bytes, checksum: 153d5257eed9a0961aaeaac94e224f89 (MD5)
Previous issue date: 2015-08-05Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Paranasal sinus are important objects of study to rhinosinusitis diagnostic, having some papers related incidence between asthma and allergic rhinitis.Many applications can calculate to various parts of the human body, getting a CT scan or MRI input, and returning information about the region of interest observed as volume and area. The accumulated mucus in the sinuses is one of the areas of interest that have not yet been implemented methods for the calculation of volume and area. In the present scenario, the patient monitoring is done visually, depending largely on perception of the evaluator. Therefore, we seek to implement more accurate metrics to facilitate medical care to the patient and it can help prevent the worsening of rhinitis in a given patient, developing mechanisms of visual and numerical comparison, where it is possible observe the progress of treatment. This work contains a detailed study of how certain existing techniques, combined into one methodology can segment and calculate the accumulated mucus in the maxillary sinus. In addition to techniques such as Thresholding, Gaussian filter, Mathematical Morphology, Metallic Artifacts Reduction during processing and segmentation, MUNC and DTA to calculate the volume and area, and visualization techniques as the Marching Cubes, it was also necessary some adjustments in the algorithm for limit the region of interest where the thresholding combined with the gaussian filter has not been effective of retaining edges. The application will use two open source platforms, one for processing, ITK, and another for visualization, VTK. The results demonstrated that it is possible to perform segmentation and the calculation with the use of platforms as well as the methodology used is adequate to solve this problem.
Os seios paranasais são importantes objetos de estudo para o diagnóstico de rinossinusites, tendo alguns estudos relacionado a incidência de asma na fase adulta a quadros de rinite alérgica na infância. Muitas aplicações atendem a diversas partes do corpo humano, obtendo de entrada uma tomografia computadorizada ou ressonância magnética, e devolvendo, muitas vezes, números que dizem respeito ao objeto de interesse observado, como volume e área. O muco acumulado nos seios paranasais é uma das regiões de interesse que ainda não tiveram métodos implementados para o cálculo do volume e área. No cenário atual, o acompanhamento do paciente é feito de forma visual, dependendo muito da percepção do avaliador. Portanto, busca-se a implementação de métricas mais precisas para facilitar o acompanhamento médico ao paciente e ajudar na prevenção do agravamento de um quadro de rinite em um determinado paciente, criando mecanismos de comparação visual e numérica, onde é possível observar a evolução do tratamento. Este trabalho contém um estudo detalhado de como determinadas técnicas existentes, combinadas em uma metodologia, podem segmentar e calcular o muco acumulado nos seios paranasais maxilares. Além de técnicas como a Binarizacão, Filtro Gaussiano, Morfologia Matemática, Redução de Ruídos Metálico durante o processamento e segmentação, MUNC e DTA para o cálculo do volume e área, e técnicas de visualização como o Marching Cubes, foram necessários também ajustes no algoritmo para limitar a área segmentada onde a binarizacão combinada ao filtro não foi capaz de manter as bordas da região de interesse. A aplicação fará uso de duas plataformas de código livre, sendo uma para o processamento, ITK, e outra para visualização de imagens, VTK. Os resultados demonstraram que é possível realizar a segmentação e o cálculo com o uso das plataformas, bem como a metodologia empregada é adequada a resolução deste problema.
43
Huff, Rafael. "Recorte volumétrico usando técnicas de interação 2D e 3D." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/7385.
Full textAbstract:
A visualização de conjuntos de dados volumétricos é comum em diversas áreas de aplicação e há já alguns anos os diversos aspectos envolvidos nessas técnicas vêm sendo pesquisados. No entanto, apesar dos avanços das técnicas de visualização de volumes, a interação com grandes volumes de dados ainda apresenta desafios devido a questões de percepção (ou isolamento) de estruturas internas e desempenho computacional. O suporte do hardware gráfico para visualização baseada em texturas permite o desenvolvimento de técnicas eficientes de rendering que podem ser combinadas com ferramentas de recorte interativas para possibilitar a inspeção de conjuntos de dados tridimensionais. Muitos estudos abordam a otimização do desempenho de ferramentas de recorte, mas muito poucos tratam das metáforas de interação utilizadas por essas ferramentas. O objetivo deste trabalho é desenvolver ferramentas interativas, intuitivas e fáceis de usar para o recorte de imagens volumétricas. Inicialmente, é apresentado um estudo sobre as principais técnicas de visualização direta de volumes e como é feita a exploração desses volumes utilizando-se recorte volumétrico. Nesse estudo é identificada a solução que melhor se enquadra no presente trabalho para garantir a interatividade necessária. Após, são apresentadas diversas técnicas de interação existentes, suas metáforas e taxonomias, para determinar as possíveis técnicas de interação mais fáceis de serem utilizadas por ferramentas de recorte. A partir desse embasamento, este trabalho apresenta o desenvolvimento de três ferramentas de recorte genéricas implementadas usando-se duas metáforas de interação distintas que são freqüentemente utilizadas por usuários de aplicativos 3D: apontador virtual e mão virtual. A taxa de interação dessas ferramentas é obtida através de programas de fragmentos especiais executados diretamente no hardware gráfico. Estes programas especificam regiões dentro do volume a serem descartadas durante o rendering, com base em predicados geométricos. Primeiramente, o desempenho, precisão e preferência (por parte dos usuários) das ferramentas de recorte volumétrico são avaliados para comparar as metáforas de interação empregadas. Após, é avaliada a interação utilizando-se diferentes dispositivos de entrada para a manipulação do volume e ferramentas. A utilização das duas mãos ao mesmo tempo para essa manipulação também é testada. Os resultados destes experimentos de avaliação são apresentados e discutidos.Visualization of volumetric datasets is common in many fields and has been an active area of research in the past two decades. In spite of developments in volume visualization techniques, interacting with large datasets still demands research efforts due to perceptual and performance issues. The support of graphics hardware for texture-based visualization allows efficient implementation of rendering techniques that can be combined with interactive sculpting tools to enable interactive inspection of 3D datasets. Many studies regarding performance optimization of sculpting tools have been reported, but very few are concerned with the interaction techniques employed. The purpose of this work is the development of interactive, intuitive, and easy-to-use sculpting tools. Initially, a review of the main techniques for direct volume visualization and sculpting is presented. The best solution that guarantees the required interaction is highlighted. Afterwards, in order to identify the most user-friendly interaction technique for volume sculpting, several interaction techniques, metaphors and taxonomies are presented. Based on that, this work presents the development of three generic sculpting tools implemented using two different interaction metaphors, which are often used by users of 3D applications: virtual pointer and virtual hand. Interactive rates for these sculpting tools are obtained by running special fragment programs on the graphics hardware which specify regions within the volume to be discarded from rendering based on geometric predicates. After development, the performance, precision and user preference of the sculpting tools were evaluated to compare the interaction metaphors. Afterward, the tools were evaluated by comparing the use of a 3D mouse against a conventional wheel mouse for guiding volume and tools manipulation. Two-handed input was also tested with both types of mouse. The results from the evaluation experiments are presented and discussed.
44
Batagini, Nayara Cioffi. "Volumetria e parâmetros biomecânicos detectados pela Ultrassonografia 3D e 2D em aortas abdominais de pacientes com e sem aneurisma." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/5/5132/tde-06012017-105117/.
Full textAbstract:
INTRODUÇÃO: O diâmetro transverso máximo (DTM) de um aneurisma da aorta abdominal (AAA), a medida mais comumente utilizada para determinar quando uma intervenção cirúrgica está indicada nos portadores desta afecção, tem limitações e não reflete o exato risco de rotura. Parâmetros biomecânicos e morfológicos detectados pelo ultrassom (US) com propriedades tridimensionais (3D), podem ajudar a melhor entender o comportamento dos AAA e a determinar o melhor momento para o tratamento cirúrgico deste grupo de pacientes. OBJETIVOS: Verificar a capacidade e a viabilidade do ultrassom bidimensional (US-2D) acoplado com algoritmos de speckletracking em avaliar as propriedades biomecânicas da aorta em pacientes com e sem AAA. Mensurar o volume parcial dos AAA através do ultrassom tridimensional (US- 3D) e compará-lo com o volume estimado pela tomografia computadorizada (TC). MÉTODOS: Este foi um estudo prospectivo. Trinta e um pacientes com aortas normais (grupo 1), 46 pacientes com AAA de diâmetro máximo entre 3,0 - 5,5 cm (grupo 2) e 31 pacientes com diâmetro dos AAA >- 5,5 cm (grupo 3) foram submetidos ao exame de US 2D/3D da aorta infrarrenal, e as imagens foram pós-processadas antes de serem analisadas. No diâmetro máximo, o strain (deformação) circunferencial global e a rotação global máxima acessados pelo algoritmo de speckle-tracking 2D foram comparados entre os três grupos. O strain regional da parede posterior foi também comparado com o da parede anterior em todos os grupos. Os dados de volumetria obtidos usando o US-3D de 40 pacientes foram comparados com os dados de volumetria obtidos por uma TC contemporânea. RESULTADOS: A mediana do strain circunferencial global foi 2,0% (interquartile range (IR): 1,0 - 3,0), 1,0% (IR: 1,0 - 2,0) e 1,0% (IR: 1,0 - 1,75) nos grupos 1, 2 e 3 respectivamente (p < 0,001). A mediana da rotação global máxima diminuiu progressivamente dos grupos 1 ao 3 (1,38º (IR: 0,77 - 2,13), 0,80º (IR: 0,57 - 1,0) e 0,50º (IR: 0,31 - 0,75) (p < 0,001)). Na análise regiãoespecífica, o pico de strain na parede posterior foi significativamente maior que na parede anterior apenas no grupo 3 (p = 0,003). Os volumes dos AAA estimados pelo US-3D tiveram boa correlação com a TC (R-square = 0,76). CONCLUSÕES: O US é capaz de detectar parâmetros biomecânicos distintos entre aortas normais, aneurismas pequenos e aneurismas grandes. A propriedade 3D do US é capaz de determinar o volume dos AAA e apresenta boa correlação com o método padrão ouro (TC). Estudos prospectivos e com seguimento longo são necessários para aprofundar a compreensão não invasiva do comportamento biomecânico e morfológico dos AAA e correlacionar esses parâmetros com o risco de roturaINTRODUCTION: The maximum transverse diameter of an abdominal aortic aneurysm (AAA), the most common measurement utilized to determine whether surgical intervention is indicated, has limitations and does not reflect the exact risk of rupture. Biomechanical and morphological parameters detected by ultrasound (US), including three-dimensional (3D) properties, can help to better understand the behavior of AAA and to determine the optimal approach to treatment in this group of patients. OBJECTIVES: To demonstrate the feasibility and the ability of the US with speckletracking algorithms to evaluate biomechanical parameters of the aorta in patients with and without abdominal aortic aneurysm (AAA). To measure the partial aneurysm volume by 3D-US and to compare it with the aneurysm volume measured by computed tomography (CT). METHODS: It was a prospective study. Thirty-one patients with normal aortas (group 1), 46 patients with AAA measuring 3.0 - 5.5 cm (group 2) and 31 patients with AAA >- 5.5 cm (group 3) underwent a 2D/3D US examination of the infrarenal aorta, and the images were post-processed prior to being analyzed. In the maximum diameter, the global circumferential strain and the global maximum rotation assessed by 2D speckle-tracking algorithms were compared among the three groups. The regional strain on posterior wall was also compared to that in the anterior wall for all groups. The volumetry data obtained using 3D-US from forty AAA patients was compared with the volumetry data obtained by a contemporary CT. RESULTS: The median global circumferential strain was 2.0% (interquartile range (IR): 1.0 - 3.0), 1.0% (IR: 1.0 - 2.0) and 1.0% (IR: 1.0 - 1.75) in groups 1, 2 and 3, respectively (p < 0.001). The median global maximum rotation decreased progressively from group 1 to 3 (1.38º (IR: 0.77 - 2.13), 0.80º (IR: 0.57 - 1.0) and 0.50º (IR: 0.31 - 0.75) (p < 0.001)). In the region-specific analysis, the strain in the posterior wall was significantly higher than anterior wall only in group 3 (p = 0.003). AAA volume estimations by 3D-US correlated well with CT (R-square = 0.76). CONCLUSIONS: The US can detect distinct biomechanical parameters between normal aorta, small aneurysms and big aneurysms. The 3D property of US is able to determine AAA volume and correlates well with the gold standard technique (CT). Prospective studies and with long-term follow-up are necessary in order to deepen the non invasive understanding of AAA biomechanical and morphological behavior and to correlate those parameters with rupture risk
45
Pinto, Francisco de Moura. "Especificação de funções de transferência unidimensionais e multidimensionais para visualização volumétrica direta." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/12077.
Full textAbstract:
O uso de dados volumétricos é bastante comum em diversas áreas da ciência, como Medicina, Física e Meteorologia. São exemplos típicos os dados provenientes de dispositivos de tomografia computadorizada ou ressonância magnética e os obtidos através de estimação de fenômenos físicos pelo uso de sensores diversos ou de simulação numérica. Tais dados apresentam-se, freqüentemente, sob a forma de uma grade tridimensional regular, onde cada elemento possui um valor escalar ou multidimensional (uma tupla de valores). Outras topologias também podem ser usadas para exprimir a disposição espacial dos valores. A visualização de dados volumétricos, importante na compreensão destes, é um processo não-trivial e, em decorrência, diversas técnicas foram propostas para abordar o problema. Visualização direta de volumes é uma abordagem em crescente popularização que representa visualmente os dados, conservando sua estrutura tridimensional, sem extrair geometrias intermediárias. Esse processo exige o mapeamento dos atributos dos elementos de volume para propriedades ópticas, permitindo a geração de imagens através da aplicação de um algoritmo de visualização, que pode implementar um modelo de iluminação. Tal mapeamento é definido por uma função, conhecida como função de transferência, que determina valores de atributos ópticos para cada valor encontrado no volume. Essa função desenvolve, portanto, um importante papel na visualização, pois define a visibilidade das estruturas presentes no volume — normalmente valendo-se do atributo opacidade — e também o aspecto destas na imagem final. Contudo, a definição de uma boa função de transferência, capaz de produzir imagens informativas, é um processo complexo que deve ser simplificado com o apoio de ferramentas adequadas. A simples especificação manual de uma função de transferência é um processo iterativo de tentativa e erro, em decorrência da dificuldade de compreensão do relacionamento entre a função utilizada e a imagem gerada, especialmente quando se trata de dados multidimensionais, que implicam funções de transferência com maior número de dimensões. Diante da necessidade de agilizar e simplificar a especificação de funções de transferência, abordagens semi-automáticas e automáticas para geração de funções foram propostas, exigindo do usuário esforço de interação reduzido ou nulo. Entretanto, as propostas existentes deixam a desejar na simplicidade, interatividade ou flexibilidade. O presente trabalho propõe técnicas de especificação de funções de transferência, para volumes escalares e multidimensionais, baseadas na automatização parcial do processo e simplificação do espaço de interação usado na definição das funções.Como principais contribuições, são apresentados uma eficaz combinação de técnicas complementares para especificação de funções de transferência para volumes escalares; e um método de especificação de funções de transferência para volumes multidimensionais que reúne o potencial de classificação dos mapas auto-organizáveis com a capacidade de decisão não-binária acerca davisibilidade e aspecto de voxels pertinente às funções de transferência tradicionais.Volume data are very often used in several areas of science, such as medicine, physics and meteorology. Typical examples are data provided by computed tomography, magnetic resonance imaging or estimation of physical phenomena through numerical simulation or sensors. Such data are often provided as regular three-dimensional grids where each element has a scalar or higher-dimensional value, though other topologies may also be employed to express the position of the values in the three-dimensional space. Visualizing volume data is very important in understanding the conveyed information, but it is also a hard task. Thus, many approaches to this problem have been developed. Direct volume rendering is a set of visualization techniques that have become very popular because they can visually represent volume data, keeping their three-dimensional structure, without extracting intermediate geometries. Such processes require a mapping from voxels’ attributes to optical attributes, which allows generating images from the data through the application of a visualization algorithm that implements an illumination model, which is often very simple. This mapping, known as transfer function, associates each volume element with values of optical properties. Therefore, transfer functions play an important role in defining the visibility and the aspect of structures inside a volume, typically using opacity and color, respectively, as optical attributes. However, the design of a good transfer function, capable of generating informative images, is a complex task which must be simplified as much as possible through the support of suitable tools. A simple manual design process is a trial-and-error effort, due to the difficulty of understanding the relationship between the transfer function and the generated image, specially when dealing with multi-dimensional volume data, which require transfer functions with a wide domain. The need to accelerate and simplify the transfer function design led to the development of several automatic and semi-automatic approaches to the problem, which can reduce or eliminate the user’s interaction effort. However, the existent proposals lack in simplicity, interactivity or flexibility. This work outlines transfer function design methods for visualization of scalar volume data and multi-dimensional volume data. We propose techniques based on partial automation of the design process and simplification of the interaction space used in TF specification. Our main contributions are an effective combination of complementary techniques for specifying transfer functions for scalar volumes; and a multi-dimensional transfer function design method that brings together the classification capabilities of self-organizing maps and the transfer functions’ ability of non-binary decision on voxels’ visibility and aspect.
46
Pollmer, Lars [Verfasser], Martin [Akademischer Betreuer] Halle, Martin [Gutachter] Halle, and Georg [Gutachter] Schmidt. "Evaluation der linksventrikulären, diastolischen Herzfunktion mittels linksatrialer Volumetrie in der Real-Time-3D-Echokardiographie / Lars Pollmer ; Gutachter: Martin Halle, Georg Schmidt ; Betreuer: Martin Halle." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1155533941/34.
Full text
47
Munaretti, Rodrigo Barni. "Perceptual guidance in mesh processing and rendering using mesh saliency." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/12673.
Full textAbstract:
Considerações de informação perceptual têm ganhado espaço rapidamente em pesquisas referentes a representação, análise e exibição de malhas. Estudos com usuários, eye tracking e outras técnicas são capazes de fornecer informações cada vez mais úteis para sistemas voltados a usuário, que formam a maioria das aplicações em computação gráfica. Neste trabalho nós expandimos sobre o conceito de Saliência de Malhas — uma medida automática de importância visual para malhas de triângulos baseada em modelos de atenção humana em baixo nível — melhorando, extendendo e realizando integração com diferentes aplicações. Nós extendemos o conceito de Saliência de Malhas para englobar objetos deformáveis, mostrando como um mapa de saliência em nível de vértice pode ser construído capturando corretamente regiões de alta importância perceptual através de um conjunto de poses ou deformações. Nós definimos saliência multi-pose como um agregado multi-escala de valores de curvatura sobre uma vizinhança localmente estável, em conjunto com deformações desta vizinhança em múltiplas poses. Nós substituímos distância Euclideana por geodésica, assim fornecendo melhores estimativas de vizinhança local. Resultados mostram que saliência multi-pose gera resultados visualmente mais interessantes em simplificações quando comparado à saliência em uma única pose. Nós também aplicamos saliência de malhas ao problema de segmentação e rendering dependente de ponto de vista, introduzindo uma técnica para segmentação que particiona um objeto em um conjunto de clusters, cada um englobando um grupo de características localmente interessantes. Saliência de malhas é incorporada em um framework para clustering propagativo, guiando seleção de pontos de partida para clusters e custos de propagação de faces, levando a uma convergência de clusters ao redor de características perceptualmente importantes. Nós comparamos nossa técnica com diferentes métodos automáticos para segmentação, mostrando que ela fornece segmentação melhor ou comparável sem necessidade de intervenção do usuário. Uma vez que o algoritmo de segmentação proposto é especialmente aplicável a rendering multi-resolução, nós ilustramos uma aplicação do mesmo através de um sistema de rendering baseado em ponto de vista guiado por saliência, alcançando melhorias consideráveis em framerate com muito pouca perda de qualidade visual.Considerations on perceptual information are quickly gaining importance in mesh representation, analysis and display research. User studies, eye tracking and other techniques are able to provide ever more useful insights for many user-centric systems, which form the bulk of computer graphics applications. In this work we build upon the concept of Mesh Saliency — an automatic measure of visual importance for triangle meshes based on models of low-level human visual attention—improving, extending and integrating it with different applications. We extend the concept of Mesh Saliency to encompass deformable objects, showing how a vertex-level saliency map can be constructed that accurately captures the regions of high perceptual importance over a range of mesh poses or deformations. We define multipose saliency as a multi-scale aggregate of curvature values over a locally stable vertex neighborhood together with deformations over multiple poses. We replace the use of the Euclidean distance by geodesic distance thereby providing superior estimates of the local neighborhood. Results show that multi-pose saliency generates more visually appealing mesh simplifications when compared to a single-pose mesh saliency. We also apply Mesh Saliency to the problem of mesh segmentation and view-dependent rendering, introducing a technique for segmentation that partitions an object into a set of face clusters, each encompassing a group of locally interesting features. Mesh Saliency is incorporated in a propagative mesh clustering framework, guiding cluster seed selection and triangle propagation costs and leading to a convergence of face clusters around perceptually important features. We compare our technique with different fully automatic segmentation algorithms, showing that it provides similar or better segmentation without the need for user input. Since the proposed clustering algorithm is specially suitable for multi-resolution rendering, we illustrate application of our clustering results through a saliency-guided view-dependent rendering system, achieving significant framerate increases with little loss of visual detail.
48
Horst, Jan-Pit [Verfasser], Kai Thorsten [Gutachter] Laser, and Thomas [Gutachter] Lücke. "Evaluation einer Wissensdatenbank-basierten Rekonstruktionssoftware zur Volumetrie des rechten Ventrikels anhand von 3D-Echkardiographie-Datensätzen / Jan-Pit Horst ; Gutachter: Kai Thorsten Laser, Thomas Lücke ; Medizinische Fakultät." Bochum : Ruhr-Universität Bochum, 2017. http://d-nb.info/1150509864/34.
Full text
49
Lengyel, Kristián. "Zobrazování medicínských dat v reálném čase." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2010. http://www.nusl.cz/ntk/nusl-235544.
Full textAbstract:
This thesis deals with design and implementation of an application for medical data imaging in real-time. The first part of project is focused on methods for obtaining data in medical practice and visualization of large volume data on computer using familiar rendering approaches. Similar applications are used outside of medicine in other fields, such as chemistry to display molecular structures or microorganisms. Another part of project will focus on benefits of visualization of volumetric data using programmable hardware and new methods of parallelization of algorithms on graphics card using CUDA technology, and OpenCL. The resulting application will display the volume of medical data based on selected method accelerated by programmable shaders, and time-consuming operations will be paralleled on graphics card.
50
Weng, Naiqi. "3D computer puppetry on volumetric displays." 2005. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=370162&T=F.
Full text