Dissertations / Theses on the topic '3D head'

The research covered in this thesis encompasses the design of novel 3D displays, a consideration of 3D television requirements and a survey of autostereoscopic methods is also presented. The principle of operation of simple 3D display prototypes is described, and design of the components of optical systems is considered. A description of an appropriate non-contact infrared head tracking method suitable for use with 3D television displays is also included. The thesis describes how the operating principle of the displays is based upon a twoimage system comprising a pair of images presented to the appropriate viewers' eyes. This is achieved by means of novel steering optics positioned behind a direct view liquid crystal display (LCD) that is controlled by a head position tracker. Within the work, two separate prototypes are described, both of which provide 3D to a single viewer who has limited movement. The thesis goes on to describe how these prototypes can be developed into a multiple-viewer display that is suitable for television use. A consideration of 3D television requirements is documented showing that glassesfree viewing (autostereoscopic), freedom of viewer movement and practical designs are important factors for 3D television displays. The displays are novel in design in several important aspects that comply with the requirements for 3D television. Firstly they do not require viewers to wear special glasses, secondly the displays allow viewers to move freely when viewing and finally the design of the displays is practical with a housing size similar to modem television sets and a cost that is not excessive. Surveys of other autostereoscopic methods included within the work suggest that no contemporary 3D display offers all of these important factors.

Ce travail présente un système de vision par ordinateur capable de faire un suivi du mouvement en 3D de la tête d’une personne dans le cadre de la conduite automobile. Ce système de vision par ordinateur a été conçu pour faire partie d'un système intégré d’analyse du comportement des conducteurs tout en remplaçant des équipements et des accessoires coûteux, qui sont utilisés pour faire le suivi du mouvement de la tête, mais sont souvent encombrants pour le conducteur. Le fonctionnement du système est divisé en quatre étapes : l'acquisition d'images, la détection de la tête, l’extraction des traits faciaux, la détection de ces traits faciaux et la reconstruction 3D des traits faciaux qui sont suivis. Premièrement, dans l'étape d'acquisition d'images, deux caméras monochromes synchronisées sont employées pour former un système stéréoscopique qui facilitera plus tard la reconstruction 3D de la tête. Deuxièmement, la tête du conducteur est détectée pour diminuer la dimension de l’espace de recherche. Troisièmement, après avoir obtenu une paire d’images de deux caméras, l'étape d'extraction des traits faciaux suit tout en combinant les algorithmes de traitement d'images et la géométrie épipolaire pour effectuer le suivi des traits faciaux qui, dans notre cas, sont les deux yeux et le bout du nez du conducteur. Quatrièmement, dans une étape de détection des traits faciaux, les résultats 2D du suivi sont consolidés par la combinaison d'algorithmes de réseau de neurones et la géométrie du visage humain dans le but de filtrer les mauvais résultats. Enfin, dans la dernière étape, le modèle 3D de la tête est reconstruit grâce aux résultats 2D du suivi et ceux du calibrage stéréoscopique des caméras. En outre, on détermine les mesures 3D selon les six axes de mouvement connus sous le nom de degrés de liberté de la tête (longitudinal, vertical, latéral, roulis, tangage et lacet). La validation des résultats est effectuée en exécutant nos algorithmes sur des vidéos préenregistrés des conducteurs utilisant un simulateur de conduite afin d'obtenir des mesures 3D avec notre système et par la suite, à les comparer et les valider plus tard avec des mesures 3D fournies par un dispositif pour le suivi de mouvement installé sur la tête du conducteur.
This work presents a computer vision module capable of tracking the head motion in 3D space for drivers. This computer vision module was designed to be part of an integrated system to analyze the behaviour of the drivers by replacing costly equipments and accessories that track the head of a driver but are often cumbersome for the user. The vision module operates in five stages: image acquisition, head detection, facial features extraction, facial features detection, and 3D reconstruction of the facial features that are being tracked. Firstly, in the image acquisition stage, two synchronized monochromatic cameras are used to set up a stereoscopic system that will later make the 3D reconstruction of the head simpler. Secondly the driver’s head is detected to reduce the size of the search space for finding facial features. Thirdly, after obtaining a pair of images from the two cameras, the facial features extraction stage follows by combining image processing algorithms and epipolar geometry to track the chosen features that, in our case, consist of the two eyes and the tip of the nose. Fourthly, in a detection stage, the 2D tracking results are consolidated by combining a neural network algorithm and the geometry of the human face to discriminate erroneous results. Finally, in the last stage, the 3D model of the head is reconstructed from the 2D tracking results (e.g. tracking performed in each image independently) and calibration of the stereo pair. In addition 3D measurements according to the six axes of motion known as degrees of freedom of the head (longitudinal, vertical and lateral, roll, pitch and yaw) are obtained. The validation of the results is carried out by running our algorithms on pre-recorded video sequences of drivers using a driving simulator in order to obtain 3D measurements to be compared later with the 3D measurements provided by a motion tracking device installed on the driver’s head.

The research covered in this thesis encompasses a consideration of 3D television requirements and a survey of stereoscopic and autostereoscopic methods. This confirms that although there is a lot of activity in this area, very little of this work could be considered suitable for television. The principle of operation, design of the components of the optical system and evaluation of two EU-funded (MUTED & HELIUM3D projects) glasses-free (autostereoscopic) displays is described. Four iterations of the display were built in MUTED, with the results of the first used in designing the second, third and fourth versions. The first three versions of the display use two-49 element arrays, one for the left eye and one for the right. A pattern of spots is projected onto the back of the arrays and these are converted into a series of collimated beams that form exit pupils after passing through the LCD. An exit pupil is a region in the viewing field where either a left or a right image is seen across the complete area of the screen; the positions of these are controlled by a multi-user head tracker. A laser projector was used in the first two versions and, although this projector operated on holographic principles in order to obtain the spot pattern required to produce the exit pupils, it should be noted that images seen by the viewers are not produced holographically so the overall display cannot be described as holographic. In the third version, the laser projector is replaced with a conventional LCOS projector to address the stability and brightness issues discovered in the second version. In 2009, true 120Hz displays became available; this led to the development of a fourth version of the MUTED display that uses 120Hz projector and LCD to overcome the problems of projector instability, produces full-resolution images and simplifies the display hardware. HELIUM3D: A multi-user autostereoscopic display based on laser scanning is also described in this thesis. This display also operates by providing head-tracked exit pupils. It incorporates a red, green and blue (RGB) laser illumination source that illuminates a light engine. Light directions are controlled by a spatial light modulator and are directed to the users’ eyes via a front screen assembly incorporating a novel Gabor superlens. In this work is described that covered the development of demonstrators that showed the principle of temporal multiplexing and a version of the final display that had limited functionality; the reason for this was the delivery of components required for a display with full functionality.

The main aim of this thesis is to generate 3D models of human heads from uncalibrated images. In order to extract geometric values of a human head, we find camera parameters using camera auto calibration. However, some image sequences generate non-unique (degenerate) solutions. An algorithm for removing degeneracy from the most common form of camera movement in face image acquisition is described. The geometric values of main facial features are computed initially. The model is then generated by gradual deformation of a generic polygonal model of a head. The accuracy of the models is evaluated using ground truth data from a range scanner. 3D models are covered with cylindrical texture values obtained from images. The models are appropriate for animation or identification applications.

HNSCC accounts for 7 percent of all new cancer occurrences. Despite currently available treatments, there continues to be a high mortality and recurrence rate in HNSCC. Well over 50 percent of all cancer patients receive chemotherapy as a standard treatment. However, only 5 percent of these cases have been shown to help with treatment of the disease. Formerly, two options were available for drug testing: in vivo animal models, and in vitro two-dimensional models. While in vivo models remain the most representative, their use is burdened by high costs, time constraints, and ethical concerns. 2D models are simple to use and cost effective, although they have been shown to produce inaccurate data regarding chemotherapeutic drug resistance due to their 2D arrangement and altered gene expression. Researchers for the past decade have been working to create 3D models that more accurately represent in vivo systems in order to evaluate chemotherapeutic efficacy and improve clinical outcomes. In line with this agenda, novel 3D head and neck cancer models were created out of electrospun synthetic polymers seeded with either HN6 or HN12 cancer cells. The models were then treated with chemotherapeutic drugs (either paclitaxel or cisplatin), and, after 72 hours, subjected to a live-dead assay in order to determine the cytotoxic effects of the drugs. 2D cultures of HN6 and HN12 were also and subject to a WST-1 assay after 72 hours. The results of the treated-scaffold assays were then compared to the results of the 2D culture assays, and, as predicted, the cancer cells in a 3D culture system proved to be more resistant to chemotherapeutic drugs. The underlying assumption for this study being that a 3D culture system based on precisely defined structural parameters would provide a practical environment to screen therapeutics for anti-cancer efficacy. To prove this, 3D scaffolds of three different fiber sizes were developed by electrospinning different concentrations of Poly(L-lactic acid) (“PLLA”) (55mg/ml, 115mg/ml, and 180mg/ml) onto a mandrel that was perforated to allow for increased porosity. The resultant small, medium, and large scaffolds were then subjected to concentrated hydrochloric acid (HCl) pretreatment in order to make them less hydrophobic. Different fiber diameters represented different ECM environments for both HN6 and HN12. It was proven that both cell types thrived best in small fibers (55mg/ml-115mg/ml) than in large fibers. It was also reaffirmed through live-dead anlaysis of cells seeded on 3D scaffolds and treated with IC90 values of cisplatin that the head and neck cancer cells were more resistant which is more representative to the 3D environment of cancer cells in vivo.

Al llarg de les últimes dècades, l'anàlisi facial ha atret un interès creixent i considerable per part de la comunitat investigadora amb l’objectiu de millorar la interacció i la cooperació entre les persones i les màquines. Aquest interès ha propiciat la creació de sistemes automàtics capaços de reaccionar a diversos estímuls com ara els moviments del cap o les emocions d’una persona. Més enllà, les tasques automatitzades s’han de poder realitzar amb gran precisió dins d’entorns no controlats, fet que ressalta la necessitat d'algoritmes que aprofitin al màxim els avantatges que proporcionen les dades 3D. Aquests sistemes poden ser útils en molts àmbits com ara la interacció home-màquina, tutories, entrevistes, atenció sanitària, màrqueting, etc. En aquesta tesi, ens centrem en dos aspectes de l'anàlisi facial: el reconeixement d'expressions i l'estimació de l'orientació del cap. En ambdós casos, ens enfoquem en l’ús de dades 3D i presentem contribucions que tenen com a objectiu la identificació de representacions significatives de la geometria facial mitjançant mètodes basats en la descomposició espectral: 1. Proposem una tecnologia basada en la representació espectral per al reconeixement d’expressions facials utilitzant exclusivament la geometria 3D, la qual ens permet una descripció completa de la superfície subjacent que pot ser ajustada al nivell de detall desitjat. Dita tecnologia, es basa en la descomposició de fragments locals de la superfície en les seves components de freqüència espacial, d’una manera semblant a la transformada de Fourier, que estan relacionades amb característiques intrínseques de la superfície. Concretament, proposem la utilització de les Graph Laplacian Features (GLFs) que resulten de la projecció dels fragments locals de la superfície a una base comuna obtinguda a partir del Graph Laplacian eigenspace. El mètode proposat s’ha avaluat en termes de reconeixement d’expressions i Action Units (activacions musculars facials), i els resultats obtinguts confirmen que les GLFs produeixen taxes de reconeixement comparables a l’estat de l’art. 2. Proposem un mètode per a l’estimació de l’orientació del cap que permet modelar el manifold subjacent que formen les rotacions generals en 3D. En primer lloc, construïm un sistema completament automàtic que combina la detecció de landmarks (punts facials rellevants) i característiques basades en diccionari, el qual ha obtingut els millors resultats al FG2017 Head Pose Estimation Challenge. Posteriorment, utilitzem una representació basada en tensors i la seva descomposició en els valors singulars d’ordre més alt per tal de separar els subespais de cada factor de rotació i mostrar que cada un d’ells té una estructura clara que pot ser modelada amb funcions trigonomètriques. Aquesta representació proporciona un coneixement detallat del comportament de les dades i pot ser utilitzada per millorar l’estimació de les orientacions dels angles del cap.
Facial analysis has attracted considerable research efforts over the last decades, with a growing interest in improving the interaction and cooperation between people and computers. This makes it necessary that automatic systems are able to react to things such as the head movements of a user or his/her emotions. Further, this should be done accurately and in unconstrained environments, which highlights the need for algorithms that can take full advantage of 3D data. These systems could be useful in multiple domains such as human-computer interaction, tutoring, interviewing, health-care, marketing etc. In this thesis, we focus on two aspects of facial analysis: expression recognition and head pose estimation. In both cases, we specifically target the use of 3D data and present contributions that aim to identify meaningful representations of the facial geometry based on spectral decomposition methods: 1. We propose a spectral representation framework for facial expression recognition using exclusively 3D geometry, which allows a complete description of the underlying surface that can be further tuned to the desired level of detail. It is based on the decomposition of local surface patches in their spatial frequency components, much like a Fourier transform, which are related to intrinsic characteristics of the surface. We propose the use of Graph Laplacian Features (GLFs), which result from the projection of local surface patches into a common basis obtained from the Graph Laplacian eigenspace. The proposed approach is tested in terms of expression and Action Unit recognition and results confirm that the proposed GLFs produce state-of-the-art recognition rates. 2. We propose an approach for head pose estimation that allows modeling the underlying manifold that results from general rotations in 3D. We start by building a fully-automatic system based on the combination of landmark detection and dictionary-based features, which obtained the best results in the FG2017 Head Pose Estimation Challenge. Then, we use tensor representation and higher order singular value decomposition to separate the subspaces that correspond to each rotation factor and show that each of them has a clear structure that can be modeled with trigonometric functions. Such representation provides a deep understanding of data behavior, and can be used to further improve the estimation of the head pose angles.

This master thesis deals with the use and technological capabilities of abrasive water jet in the application of 3D cutting head. One part of this thesis is the description of waterjet technology and its other applications. The experimental comparison of the effect of the parameters was carried out for different materials Mach 4 equipment Flow International Corporation in company AWAC, spol. s.r.o. and subsequently the workpieces were subjected to evaluation of the shape and dimensional accuracy.

One of the greatest challenges in achieving accurate positioning in head and neck radiotherapy is that the anatomy at and above the cervical spine does not act as a single, mechanically rigid body. Current immobilization techniques contain residual uncertainties that are especially present in the lower neck that cannot be reduced by setting up to any single landmark. The work presented describes the development of a radiotherapy friendly mostly-plastic 6D robotic platform for positioning independent landmarks, (i.e., allowing remote, independent positioning of the skull relative to landmarks in the thorax), including analysis of kinematics, stress, radiographic compatibility, trajectory planning, physical construction, and phantom measurements of correction accuracy. No major component of the system within the field of imaging or treatment had a measured attenuation value greater than 250 HU, showing compatibility with x-ray-based imaging techniques. Relative to arbitrary overall setup errors of the head (min = 1.1 mm, max = 5.2 mm vector error) the robotic platform corrected the position down to a residual overall error of 0.75 mm +/- 0.33 mm over 15 cases as measured with optical tracking. This device shows the potential for providing reductions to dose margins in head and neck therapy cases, while also reducing setup time and effort.

This thesis presents a motion compensation method based on orbital navigator echoes that measure the movement of a subject between subsequent acquisitions of a magnetic resonance image (MRI). The 3D orbital navigator method proposed addresses the speed requirements of a fast acquisition technique, namely echo planar imaging (EPI), used in functional MRI. Three orthogonal magnetic field gradient pulses were designed and implemented to produce circular sampling trajectories in the volume of the resonating spins of the subject under study. The variations in phase and magnitude of the subsequent navigator data samples serve as markers for motion occurring between repeated acquisitions. Algorithms to estimate the parameters of motion from the navigator signals were developed and their correctness and stability in the presence of noise were tested by means of numerical simulation. The phantom studies involving controlled rotation and displacement of an inhomogeneous test object during an MRI acquisition established the technique's accuracy. In-vivo experiments showed that the navigator echoes can be used in measuring the gross patient movement, as well as in monitoring the small displacements that may correlate with the respiratory cycle.

This thesis describes the acquisition of maxillo-facial soft tissue thickness data and its integration into a Computer Aided Design based solid model of the human head. The final outcome was a significant element in a novel approach to the creation of a 3D modeller for detailed study of the design of protective equipment at the interface with the skin tissues. Anthropometric surface data of 300 head 3D profiles were acquired using a laser scanning system consisting of a dual mirror configuration and a CCD video camera. Approximately 70,000 data points are scanned in less than ten seconds. The resulting surface model has a resolution of +/-0.5mm circumferentially and +/- 0.2mm radially. Soft tissue thickness values have been measured using A-scanning ultrasound system with a pulsed, 12.5MHz focused ultrasound probe with an axial resolution of 0.31mm and a lateral resolution of 2.7mm. The accuracy of the measurements has been estimated as +/-0.25mm. A novel representation of these data has been suggested in which quasi iso-thickness zones have been identified. These zones, where the thickness values are often consistent to within as little as +/-0.5mm, have been shown to be consistent with key anatomical regions. Colour spectral plots visualise the tissue zones. The thickness data are referenced to the laser data using a magnetic spacing system, POLHEMUS by 3DSpaceRTM the resulting 3D soft tissue model has important uses in Finite Element Analysis methods for design of protective equipment.

The aim of this thesis was to design and implement the interactive Java applet used for topography 3D optic nerve head visualization. Primary purpose of the 3D vizualization is ophthalmology, especially for diagnosis of glaucoma. More over should serve as a training material, which enables to study the transformation of 2D figures to 3D model and to test the effects of adjustments and regulations to imaging of the model in 3D space. Two program versions were designed in this work using the development system NetBeans version 5.5. Their final realization is implemented as .html application working in web browser window. First version of the designed applet is simple intuitive application with several default settings, so that the figure is opened automatically to 3D model. Subsequently, the applet enables to set the size of the image, 3D depth of the image, smoothing of the surface and selection of monochrome or coloured image. The second version is the extension of the first version of the designed applet, and provides the possibility to display x, y, z axis, depiction of the 3D model surface by dots, curves or grid, and illumination of the surface. Software was tested on available topographic data acquired by HRT equipment and in different web browsers. Technical documentation and user’s manual are also involved in this thesis.

With the development of posibilities of image processing, stereoscopy, prices of web cameras and power of computers an opportunity to multiply an experience with working with 3D programs showed. From the picture from webcamera an estimation of a pose of user's head can be made. According to this pose a view on 3D scene can be changed. Then, when user moves his head, he will have a feeling as if monitor was a window through which one can see the scene behind. With the system which is the result of this project it will be possible to easily and cheaply add this kind of behaviour to any 3D application.

The aim of the work is to design and manufacture a mechanism for setting up and clamping the replaceable head of a 3D FDM printer. The first part of the thesis deals with 3D printing in general, the second part describes the FDM method. Part three is devoted to the selection and construction of a suitable 3D printer, the fourth part to the actual design of the head attachment. In the fifth part, a technical and economic evaluation is carried out.

A visualização 3D de simulações pelo Método dos Elementos Finitos (MEF) ainda é uma experiência limitada em função da falta de realismo 3D nos monitores disponíveis. Além do monitor 3D realista, a melhor visualização destas simulações depende de uma apresentação MEF desenvolvida adequadamente, de forma a tirar maior proveito deste realismo 3D. Neste trabalho, é realizado o desenvolvimento de um visualizador MEF 3D, que reproduz os efeitos estereoscópicos e de rastreamento de cabeça (head-tracking), explorando melhor as percepções de profundidade com hardware acessível e bibliotecas gráficas utilizadas em aplicações convencionais.
The 3D visualization of Finite Element Method (FEM) simulations is still a limited experience due to the lack of realism of 3D monitors available. In addition to the realistic 3D monitor, better visualization of these simulations depends on a MEF presentation properly developed in order to get the most out of 3D realism. In this work, a 3D MEF viewer is develop, including stereoscopy and head tracking 3D effects, that better explores human depth cues using hardware from cost and benefit perspective and graphics libraries used in conventional applications.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 67).
This thesis discusses the design, characterization and optimization of a low-cost additive rapid-prototyping tool head for a technology known as Fused Filament Fabrication for use in an educational curriculum. Building a 3D printer represents an excellent educational opportunity as it requires knowledge in electronics, mechanics, and thermal-fluids engineering; this particular design also includes a flexural bearing, introducing students to a new and important class of machine element. Polymer flow through the extruder is modeled as pipe flow with pressure drops using Bernoulli's equation with viscous losses; the model predicts that the pressure required to extrude is proportional to 1/d⁴' , where d is the nozzle diameter. Three different extruder designs are considered; a piston-based design, an auger-based design, and a pinch-wheel design. The pinch wheel design best meets the functional requirements after comparing the designs based on factors such as complexity and controllability. Flexural bearings are selected to provide a preload against the polymer filament; HDPE was chosen to be the flexure material after considering factors such as water-jet machinability and yield stress to elastic modulus ratio. Thermal imaging shows that the temperature profile along the heater barrel is not uniform, with the largest variation being 80±2.8°C in large part due to errors in heater wire distribution during assembly. An exponential relationship is observed between the force required to extrude versus the temperature of the heater barrel with the force required to extrude dropping to between 1 and 2N in the range of 200 to 240°C. This data suggests trade-offs between maintaining a reasonable extruding pressure and maintaining good build resolution and speed. A discussion of the low cost rapid prototyping cycle follows, as well as instructions for assembly and use of the extruder. The paper ends with several suggestions to improve extruder performance and a list of ideas for bringing the extruder costs down.
by Aaron Eduardo Ramirez.
S.B.

This thesis investigates the viability of a new communication medium for telepresence, namely a robotic head with a 3D face mask. In order to investigate this, a program was developed for an existing social robot, enabling the robot to be used as a device reflecting the facial movements of the operator. A study is performed with the operator located in front of a computer with a web camera, connected to speak through the robot to two interlocutors located in a room with the robot. This setup is then compared to a regular video call. The results from this study show that the robot improves the presence of the operator in the room, along with providing enhanced simulated gaze direction and eye contact with the interlocutors. It is concluded that using a robotic head with a 3D face mask is a viable option for a communication medium for telepresence.
Denna uppsats utforskar gångbarheten för ett nytt kommunikationsmedium för telenärvaro, nämligen ett robothuvud med en 3D-ansiktsmask. För att undersöka detta har ett program utvecklats för en existerande social robot, som möjliggör att roboten kan återspegla operatörens ansiktsrörelser. En studie utförs med en operatör placerad framför en dator med en webbkamera, där operatören kopplas genom roboten för att prata med två samtalspartner som är i samma rum som roboten. Detta arrangemang jämförs sedan med ett vanligt videosamtal. Resultaten från studie visar att roboten förbättrar operatörensnärvaro i rummet, och dessutom ger förbättrad simulerad blickriktning och ögonkontakt med samtalspartnerna. Slutligen fastställs att ett robothuvud med en 3D-ansiktsmask är ett gångbart kommunikationsmedium för telenärvaro.

Head mounted projection display (HMPD) technology, as an alternative to conventional head mounted displays (HMD), offers a potential of designing wide field-of-view (FOV), low distortion optical see-through HMDs (OST-HMDs). Existing HMPD designs, however, suffer from problems of low luminance and low image resolution, which limits the applications of such information displays for the scenarios which require high luminance and high image fidelity. The design of a polarized head mounted projection display (p-HMPD) was recently proposed to overcome the challenge of low luminous efficiency in existing HMPD designs. Polarization management was employed to reduce the light loss caused by beamsplitting in an HMPD.The work in this dissertation focuses on the development and evaluation of an SXGA resolution, high efficiency p-HMPD system. The main contributions are as follows. First, the key elements in the polarization management scheme of a p-HMPD were selected and their polarization performances were characterized by measuring their Mueller matrices, based on which the overall display performance of a p-HMPD was analyzed.Second, based on a pair of ferroelectric liquid-crystal-on-silicon (FLCoS) microdisplays, a compact illumination unit and a light-weight projection system were designed, from which a p-HMPD prototype was built. Following the prototype implementation, a series of calibrations were performed to obtain correct color presentation, desired focusing setting, and optical system characteristics necessary for achieving accurate registration between virtual objects and their counterparts in the real world.Third, the imaging properties of a retroreflective screen which is an essential part of a p-HMPD or HMPD were studied and its effects on the image resolution of an HMPD system were further characterized.Finally, the performance of the system was evaluated through two objective user experiments, including a visual acuity assessment and a depth perception accuracy assessment.

The diploma thesis is focused on waterjet technology, dimensional and shape accuracy of manufactured parts. In the theoretical section, the principle of technlogy and its use in engineering industry at the present time, are described. Moreover, the theoretical section includes discription of every single parts of the machine of waterjet cutting, that are nowadays used. The biggest part of diploma thesis focuses on 3D cutting technology and on attachments for elimination of undercutting. Practical section focuses on dimensional and shape accuracy of manufactured parts manufactured by waterjet technology that makes use of 3D head and different cutting speed. The practical section also includes operating and maintenance cost of the machine. In terms of maintenance, real service life of components is compared there with a lifespan declarated by machine producer.

Dreidimensionale Informationsvisualisierungen fördern durch den geringen Grad an Abstraktion die Bildung eines präzisen mentalen Modells und können daher multidimensionale räumliche Beziehungen greifbar kommunizieren. Gleichzeitig eröffnet die aktuelle Generation von Augmented Reality Head-Mounted Displays (AR-HMDs) neuartige Möglichkeiten zur Exploration von 3D-InfoVis und ist befähigt virtuelle Objekte glaubwürdig und immersiv in die physische Umgebung eines Nutzers zu integrieren. Dennoch unterliegt die Interaktion in AR-Umgebungen einer Vielzahl von Herausforderungen, da die signifikante Mehrheit der Applikationen lediglich Blick-, Freihandgesten- oder Sprachsteuerung als Eingabemodalität in Betracht ziehen. Durch Kombination von interaktiven Oberflächen wie Tabletops mit AR-HMDs können diese Nachteile effizient adressiert werden, indem direkte und natürliche Manipulation in Form von Multi-Touch, Tangible- oder Stift-Eingabe ermöglicht wird. Im Rahmen dieser Thesis wird untersucht, wie die Analyse von 3D-InfoVis bei Kombination interaktiver Oberflächen mit AR-HMDs unterstützt werden kann. Hierfür wird der aktuelle Stand der Forschung in themennahen Domänen erfasst und folgend Konzepte zur Unterstützung analytischer Prozesse in zuvor erläuterter Systemkonstellation entwickelt. Die resultierenden Konzepte adressieren dabei Limitationen, die bei Darstellung und Interaktion von und mit 3D-InfoVis in konventionellen Systemen bestehen und im Rahmen der Kombination interaktiver Oberflächen mit AR-HMDs gelöst oder wesentlich angereichert werden können. Ausgewählte Features wurden in einer prototypischen Implementierung realisiert und getestet
Three-dimensional information visualizations aid precise mental models and are able to communicate multidimensional-spatial relations due too their low level of abstraction. Simultaneously the current generation of Augmented Reality head-mounted displays (AR-HMDs) are offering novel chances for the exploration of 3D-InfoVis and are capable of immersively integrating virtual object into the physical environment of a user. Nevertheless, interaction in AR-environments is still posing a major challenge due to most applications only considering gaze, freehand gesture or speech as input modalities. By combining AR-HMDs with interactive surfaces these limitations can be addressed and direct and natural interaction in the form of multi-touch-, tangible- or pen-input can be enabled. In the scope of this thesis it will be examined how the analysis of 3D-InfoVis can be supported in the context of combining interactive surfaces with AR-HMDs. Therefor the current state of research in associated domains is being summarized and based on that concepts for supporting analytical processes in aforementioned system constellation are being developed. The resulting concepts help addressing limitations, that exist in the representation and interaction of and with 3D-InfoVis in conventional systems in the scope of combining interactive surfaces with AR-HMDs in order to overcome them or reduce their effects. Selected features were implemented and tested in a prototype

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Title as it appears in the MIT Commencement Exercises program, June 5, 2015: HandsOn: a portable system AR-based remote collaboration Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 61-62).
In this increasingly globalized and technological world, professionals often have to collaborate remotely on 3D content, especially in fields such as urban planning or architectural design. We propose HandOn, a portable system for collaboration on virtual 3D objects. HandsOn leverages the recent advances in optical head-mounted display and finger tracking technology, allowing users to view digital content as if it were merged with the physical reality, while being able to manipulate the objects using simple hand gestures. Supporting both co-located and remote collaboration, this proof-of-concept system is designed to be portable and easy-to-setup, in contrast with many previous systems that require elaborate setup. Our findings suggests that HandsOn greatly increases awareness of remote collaborators and their actions by displaying the remote user'-s hands while interacting with the virtual objects, and that gestural hand-based interactions felt natural to the users. We also found that the illusion of the physical and the virtual being merged improved the overall experience, even though this aspect could be further improved by using better hardware.
by Kevin Winata Wong.
M. Eng.

The explorative examination of constructed 3D models in immersive environments requires suitable user-centric interaction methods. Especially novel concepts for virtual camera control can offer advantages, e.g. for the analysis of model details. We extend the known concept of the camera-in-hand metaphor and implement a multidimensional viewport control technique that can be used with common head-mounted displays and VR-controllers. With our head-in-hand view the user is able to control the virtual camera directly by hand without losing the flexibility of head movements. To ensure convenient operation, the method restricts special rotation parameters and smoothes jerky gestures of the user hand. Inaddition, we discuss implications and improvement potential of the proposed concept as well as adverse effects on the user, such as motion sickness.

This diploma thesis deals with a design and manufacture of an active print head used for 3D printing of concrete mixtures. The aim is to ensure functional parameters of the print head at a minimal mass. Extrusion of the material from the print head is ensured by a screw conveyor, shaping of the material is carry out by a rotatably mounted nozzle provided with trowels. The dimensioning of the main elements of the print head is based on the parameters measured during tests with the older version of the print head and on the FEM analysis. The print head was manufactured and is able to extrude concrete mixture with an admixture of aggregate (fraction 4–8 mm) at a rate of 0,5–2 m3•h-1. The weight of the print head is 16.4 kg, which is 30 percent less than an older print head weighed. The manufactured print head was tested during the printing of a real object and met all the required parameters. The print head is ready for implementation in a machine providing large-scale printing of parts in the construction industry.

The master thesis deals with design of multi material FDM 3D printer. In the first part, current market situation and possible principles of multi material printing are described. Possible variants of individual construction nodes are described in the next part and then the selected variant is processed into a design solution. The benefit of this thesis is a proposal of solution for the automatic printing head exchange, which is practically not concerned by printer manufacturers.

3D human face reconstruction has been an extensive research for decades due to its wide applications, such as animation, recognition and 3D-driven appearance synthesis. Although commodity depth sensors are widely available in recent years, image based face reconstruction are significantly valuable as images are much easier to access and store. In this dissertation, we first propose three image-based face reconstruction approaches according to different assumption of inputs. In the first approach, face geometry is extracted from multiple key frames of a video sequence with different head poses. The camera should be calibrated under this assumption. As the first approach is limited to videos, we propose the second approach then focus on single image. This approach also improves the geometry by adding fine grains using shading cue. We proposed a novel albedo estimation and linear optimization algorithm in this approach. In the third approach, we further loose the constraint of the input image to arbitrary in the wild images. Our proposed approach can robustly reconstruct high quality model even with extreme expressions and large poses. We then explore the applicability of our face reconstructions on four interesting applications: video face beautification, generating personalized facial blendshape from image sequences, face video stylizing and video face replacement. We demonstrate great potentials of our reconstruction approaches on these real-world applications. In particular, with the recent surge of interests in VR/AR, it is increasingly common to see people wearing head-mounted displays. However, the large occlusion on face is a big obstacle for people to communicate in a face-to-face manner. Our another application is that we explore hardware/software solutions for synthesizing the face image with presence of HMDs. We design two setups (experimental and mobile) which integrate two near IR cameras and one color camera to solve this problem. With our algorithm and prototype, we can achieve photo-realistic results. We further propose a deep neutral network to solve the HMD removal problem considering it as a face inpainting problem. This approach doesn't need special hardware and run in real-time with satisfying results.

Thesis (Ph.D.)--Case Western Reserve University, 2009
Abstract Title from OhioLINK abstract screen (viewed on 13 April 2009) Department of Biomedical Engineering Available online via the OhioLINK ETD Center

Conventional stereoscopic displays present a pair of stereoscopic images on a single and fixed image plane. In consequence, these displays lack the capability of correctly rendering focus cues (i.e. accommodation and retinal blur) and may induce the discrepancy between accommodation and convergence. A number of visual artifacts associated with incorrect focus cues in stereoscopic displays have been reported, limiting the applicability of these displays for demanding applications and daily usage. Depth-fused multi-focal-plane display was proposed to create a fixed-viewpoint volumetric display capable of rendering correct or nearly-correct focus cues in a stereoscopic display through a small number of discretely placed focal planes. It effectively addresses the negative effects of conventional stereoscopic displays on depth perception accuracy and visual fatigue. In this dissertation, the fundamental design methods and considerations of depth-fused displays were refined and extended based on previous works and a high-resolution optical see-through multi-focal-plane head-mounted display enabled by state-of-the-art freeform optics was developed. The prototype system is capable of rendering nearly-correct focus cues for a large volume of 3D space extending into a depth range from 0 to 3 diopters at flicker-free speed. By incorporating freeform optics, the prototype not only achieves high quality imagery across a large 3D volume for the virtual display path but it also maintains better than 0.5 arcminutes visual resolution of the see-through view. The optical design, implementation and experimental validation of the display are presented and discussed in detail.

Genom åren har intresset för och satsningar på underhållning i tredimensionellt format (3D) gått i vågor. Idag har de flesta biografer stöd för att visa 3D-filmer. Utöver detta intresse har det på senare år även börjat komma mer teknik för 3D i hemmet. Det har också introducerats många nya mer immersiva och intuitiva inmatnings-enheter som bidrar till under-hållning med element av virtual reality hemma. Företagen Sony, Nintendo och Microsoft har alla lanserat olika typer av avancerade tekniker för sådana inmatnings-enheter till sina spel-system. Dessa tekniker bidrar på olika sätt till mer immersiv underhållning. På de sätt som många av teknikerna används idag blir däremot interaktionen fortfarande hämmad av att dessa kräver att man står, respektive tittar, i en viss riktning.Rapporten återger en experimentell studie som tar sikte på att undersöka om det är möjligt att med kommersiellt tillgänliga medel skapa immersiv virtual reality som är portabel och buren – för underhållning i hemmet. Inledningsvis redogörs kortfattat för människans upp-fattning av djup samt hur olika 3D-displayer fungerar. Härefter kommer vi in på virtual reality och betydelsen av en hög nivå av immersion i detta sammanhang. Beträffande virtual reality kommer däremot utgångspunkten vara mer teoretisk, för att ge en bild av åt vilket håll utvecklingen går. Denna del går därmed längre än vad experimentet omfattar, eftersom denna teori inte ännu fullt ut omsatts i praktiken. Hypotesen för experimentet är att tekniken ”head tracking”, i form av en huvudburen rörelsedetektor som känner av huvudets orientering, till viss del kan vara en lösning på problemet med immersion – eftersom jag som användare då inte är hänvisad till en viss plats. Slutligen analyseras såväl teori som experiment och man kommer fram till att VRD är en möjlig lovande framtida teknik. Hypotesen bekräftas till viss del och rapporten mynnar ut i en slutreflektion där det konstateras att teknik för att skapa ökad immersion och VR hemma finns tillgänglig – även om en del ytterligare arbete för datahantering skulle krävas för att optimera denna.
Through the years, interest in and focus on entertainment in three dimensional form (3D) has gone in waves. Today, most cinemas have support for showing 3D-movies. In addition to this interest, an increasing amount of technology for 3D at home has become available in recent years. A number of different new, more immersive and intuitive input devices with elements of virtual reality for home use, have also been introduced. The companies Sony, Nintendo and Microsoft have all launched various types of such advanced input technology for their game consoles. These techniques contribute in various ways to more immersive entertain-ment. In the way many of these technical solutions are used today, they are still limited by the requirement of standing and looking in a specific direction. The report reflects an experimental study that aims to explore the feasibility of using commercially obtainable material to create immersive virtual reality for home entertainment, which is portable and wearable. Initially it explains the basics of human depth perception, and how different 3D displays work. Hereafter, we will look at virtual reality and the im-portance of a high level of immersion in this context. In regards to virtual reality however, the starting point will be of a more theoretical nature, to give an idea of in which direction the development is heading. This part thereby goes further than what the experiment covers, because of this theory not yet beeing fully applied in practice. The hypothesis for the experiment is that the technology "head tracking", in the form of a head-mounted motion-sensor that detects the orientation of the head, in part, may be a solution to the problem of immersion – as the user isn’t dependant on a specific location.Finally an analysis of both theory and experiment is made in which it is concluded that VRD might be a promissing future technology. The hypothesis is partially confirmed and the report culminates in a final reflection where it is found that technology for creating a higher level of immersion and VR at home is available – even though some additional work with data handling would be required.

This thesis deals with improvement of 3D-manipulator which is currently used for 3D printing. The improvement involves adding a new printer head which will be able to acquire various colors by mixing up to three materials. Furthermore, device is extended with milling as a finishing process responsible for better surface quality of printed object.

Esta dissertação apresenta um novo método para cálculo da pose da cabeça em imagens monoculares. Este cálculo é estimado no sistema de coordenadas da câmera, comparando as posições das características faciais específicas com as de múltiplas instâncias do modelo da face em 3D. Dada uma imagem de uma face humana, o método localiza inicialmente as características faciais, como nariz, olhos e boca. Estas últimas são detectadas e localizadas através de um modelo ativo de forma para faces. O algoritmo foi treinado sobre um conjunto de dados com diferentes poses de cabeça. Para cada face, obtemos um conjunto de pontos característicos no espaço de imagem 2D. Esses pontos são usados como referências na comparação com os respectivos pontos principais das múltiplas instâncias do nosso modelo de face em 3D projetado no espaço da imagem. Para obter a profundidade de cada ponto, usamos as restrições impostas pelo modelo 3D da face por exemplo, os olhos tem uma determinada profundidade em relação ao nariz. A pose da cabeça é estimada, minimizando o erro de comparação entre os pontos localizados numa instância do modelo 3D da face e os localizados na imagem. Nossos resultados preliminares são encorajadores e indicam que a nossa abordagem produz resultados mais precisos que os métodos disponíveis na literatura.
This dissertation presents a new method to accurately compute the head pose in mono cular images. The head pose is estimated in the camera coordinate system, by comparing the positions of specific facial features with the positions of these facial features in multiple instances of a prior 3D face model. Given an image containing a face, our method initially locates some facial features, such as nose, eyes, and mouth; these features are detected and located using an Adaptive Shape Model for faces , this algorithm was trained using on a data set with a variety of head poses. For each face, we obtain a collection of feature locations (i.e. points) in the 2D image space. These 2D feature locations are then used as references in the comparison with the respective feature locations of multiple instances of our 3D face model, projected on the same 2D image space. To obtain the depth of every feature point, we use the 3D spatial constraints imposed by our face model (i.e. eyes are at a certain depth with respect to the nose, and so on). The head pose is estimated by minimizing the comparison error between the 3D feature locations of the face in the image and a given instance of the face model (i.e. a geometrical transformation of the face model in the 3D camera space). Our preliminary experimental results are encouraging, and indicate that our approach can provide more accurate results than comparable methods available in the literature.

L'analyse morpho-fonctionnelle précise de l'épaule, notamment au niveau de l'articulation glénohumérale (GH), permettrait d'améliorer notre compréhension des dysfonctions de l'épaule associées aux ruptures de la coiffe des rotateurs. Cependant, des difficultés techniques compliquent l'analyse de la morphologie et du mouvement de l'épaule dans un contexte clinique. Dans le cadre de la présente thèse, une méthode d'analyse 3D des translations GH basée sur l'acquisition de séquences de radiographies biplanes sous EOS™ a été développée. Une étude pilote sur 10 sujets sains a d'abord permis de vérifier la facilité d'application d'un protocole d'acquisition des images et d'évaluer la répétabilité de l'identification des repères anatomiques de l'épaule sur les radiographies. La méthode proposée en dernier lieu permet, suite à l'acquisition de radiographies, de reconstruire un modèle personnalisé morpho-réaliste de la scapula et un modèle simplifié de l'humérus. Ces modèles sont ensuite recalés interactivement sur les images acquises à différentes positions du bras et utilisés pour décrire les translations GH à ces positions. La méthode a été validée en termes de précision et de répétabilité sur des images acquises d'épaules cadavériques et de patients ayant des ruptures de la coiffe des rotateurs. La dernière partie du travail présenté ici consiste à appliquer la méthode développée à 30 sujets (25 patients et 5 sujets sains) pour lesquels l'état de la coiffe des rotateurs et la fonction de l'épaule ont été évalués, puis à étudier les corrélations entre les translations GH et la fonction de l'épaule
Precise morpho-functional analysis of the shoulder, including of the glenohumeral (GH) joint, would allow improving our understanding of shoulder dysfunction associated to rotator cuff tears. However, technical difficulties make analysis of shoulder morphology and motion difficult in a clinical setting. The work carried out during this thesis allowed developing a method for 3D analysis of GH translations relying on the acquisition of sequences of biplanar radiographs with the EOS™ system. A pilot study carried out on 10 healthy subjects allowed verifying the ease of application of an image acquisition protocol and evaluating the repeatability of shoulder landmark identification on the radiographs. The final proposed method allows, following the acquisition of radiographs, obtaining a personalized morphologically realistic reconstruction of the scapula and a simplified model of the humerus. These models are then interactively registered to the images acquired at different arm positions and used to describe GH translations for these positions. The proposed method was validated in terms of precision and repeatability on images acquired of cadaveric shoulders and of patients with rotator cuff tears. The last part of the work presented here consists in applying the developed method to 30 subjects (25 patients and 5 asymptomatic subjects) for whom rotator cuff condition and shoulder function were assessed, and to study correlations between GH translations and shoulder function

This dissertation provides empirical evidence for the effects of the fidelity of VR system components, and novel 3D interaction techniques for analyzing volume datasets. It provides domain-independent results based on an abstract task taxonomy for visual analysis of scientific datasets. Scientific data generated through various modalities e.g. computed tomography (CT), magnetic resonance imaging (MRI), etc. are in 3D spatial or volumetric format. Scientists from various domains e.g., geophysics, medical biology, etc. use visualizations to analyze data. This dissertation seeks to improve effectiveness of scientific visualizations. Traditional volume data analysis is performed on desktop computers with mouse and keyboard interfaces. Previous research and anecdotal experiences indicate improvements in volume data analysis in systems with very high fidelity of display and interaction (e.g., CAVE) over desktop environments. However, prior results are not generalizable beyond specific hardware platforms, or specific scientific domains and do not look into the effectiveness of 3D interaction techniques. We ran three controlled experiments to study the effects of a few components of VR system fidelity (field of regard, stereo and head tracking) on volume data analysis. We used volume data from paleontology, medical biology and biomechanics. Our results indicate that different components of system fidelity have different effects on the analysis of volume visualizations. One of our experiments provides evidence for validating the concept of Mixed Reality (MR) simulation. Our approach of controlled experimentation with MR simulation provides a methodology to generalize the effects of immersive virtual reality (VR) beyond individual systems. To generalize our (and other researchers') findings across disparate domains, we developed and evaluated a taxonomy of visual analysis tasks with volume visualizations. We report our empirical results tied to this taxonomy. We developed the Volume Cracker (VC) technique for improving the effectiveness of volume visualizations. This is a free-hand gesture-based novel 3D interaction (3DI) technique. We describe the design decisions in the development of the Volume Cracker (with a list of usability criteria), and provide the results from an evaluation study. Based on the results, we further demonstrate the design of a bare-hand version of the VC with the Leap Motion controller device. Our evaluations of the VC show the benefits of using 3DI over standard 2DI techniques. This body of work provides the building blocks for a three-way many-many-many mapping between the sets of VR system fidelity components, interaction techniques and visual analysis tasks with volume visualizations. Such a comprehensive mapping can inform the design of next-generation VR systems to improve the effectiveness of scientific data analysis.
Ph. D.

In radiation therapy an uncertainty in the delivered dose always exists because anatomic changes are unpredictable and patient specific. Image guided radiation therapy (IGRT) relies on imaging in the treatment room to monitor the tumour and surrounding tissue to ensure their prescribed position in the radiation beam. The goal of this thesis was to determine the dosimetric impact on the misaligned radiation therapy target for three cancer sites due to common setup errors; organ motion, tumour tissue deformation, changes in body habitus, and treatment planning errors. For this purpose, a novel 3D ultrasound system (Restitu, Resonant Medical, Inc.) was used to acquire a reference image of the target in the computed tomography simulation room at the time of treatment planning, to acquire daily images in the treatment room at the time of treatment delivery, and to compare the daily images to the reference image. The measured differences in position and volume between daily and reference geometries were incorporated into Monte Carlo (MC) dose calculations. The EGSnrc (National Research Council, Canada) family of codes was used to model Varian linear accelerators and patient specific beam parameters, as well as to estimate the dose to the target and organs at risk under several different scenarios. After validating the necessity of MC dose calculations in the pelvic region, the impact of interfraction prostate motion, and subsequent patient realignment under the treatment beams, on the delivered dose was investigated. For 32 patients it is demonstrated that using 3D conformal radiation therapy techniques and a 7 mm margin, the prescribed dose to the prostate, rectum, and bladder is recovered within 0.5% of that planned when patient setup is corrected for prostate motion, despite the beams interacting with a new external surface and internal tissue boundaries. In collaboration with the manufacturer, the ultrasound system was adapted from transabdominal imaging to n
Des incertitudes dans la dose délivrée aux patients existent toujours car les changements anatomiques sont imprévisibles et spécifiques à chaque patient. La radiothérapie guidée par l'image (IGRT) dépend de l'imagerie en ligne afin de suivre la tumeur et les tissus sains adjacents, et s'assure que leur positions, par rapport au faisceau de radiation, est telle que planifiés. L'objectif de cette thèse a été de déterminer l'impact dosimétrique du désalignement de la cible par rapport au faisceau de radiation du aux erreurs d'installation, aux mouvement des organes, à la déformation de la tumeur, aux changements de l'habitus du corps et aux erreurs dans la planification du traitement. À cette fin, un nouveau système ultrason 3D (Restitu, Resonant Medical, Inc.) a été utilisé pour acquérir des images référence de la cible dans la salle de simulation tomodensitométrique au moment de la planification du traitement, et ensuite pour acquérir des images quotidiennes de la cible au moment du traitement. Les images quotidiennes ont été comparées à l'image de référence et les différences de position et volume ont été incorporées dans des calculs de dose Monte Carlo. La famille de logiciels EGSNRC (National Research Council, Canada) a été utilisée pour modéliser des accélérateurs linéaires Varian et des paramètres spécifiques à chaque patient ainsi que pour estimer la dose à la cible et aux organes à risque. Premièrement, les calculs de dose Monte Carlo, longs mais précis, ont été validés pour la région homogène du pelvis. Ensuite, l'influence du mouvement de la prostate inter fractions et du réalignement du patient sur la distribution de dose délivrée a été investiguée. Pour 32 patients nous avons démontré que l'utilisation des techniques conformes 3D combinée à une marge de 7 mm autour de la cible se traduit par une différence de moins de 0.5% entre la dose délivrée et la dose planifiée pour la prostate,$

Groundwater issues are among the most important sustainability studies related to topics considered as critical point for the future of planet Earth(Gleeson et al., 2010) in the perspective of a sustainable world. Analyses are focused on two complementary aspects: quantity and quality.Thus, once physical behaviour is analysed, it is coupled with chemical characterisation studies, in order to obtain a better view of an investigated site.The work begins with a brief overview of the literature which summarizes the challenges of teaching hydrogeology by theoretical lessons coupled with practical activities. The focus is on laboratory experiments implemented on physical models. In fact, to fully understand the process of groundwater flow and solute transport, and to demonstrate the basics fundamental concepts behind, it is important to visualize them in a lab-scale. This thesis is undertaken in the context of the installation of a 3D physical model at the University of Liège as a support to teaching and research works: dimension, set up, construction and support devices used for system optimal functioning are presented. The global aim of the work is to prepare everything needed to set up the sand tank. This is a fundamental step in order to be able to pre-dimension real experiments, to give ideas about the magnitude order of the expected results and to check the reliability of mathematical results and/or low-dimensionality models. Part of the document is centred on the characterization of porous aquifer materials to implement in the physical model, in particular through sand column one-dimensional lab experiments performed on four distinguished types of quartz sands (differentiated by the particles size) in particular a Constant Head Permeability Test and a Salt Tracer Test(KCl).A numerical model of the 3D tank is also developed by the use of GMS-MODFLOW-MT3DS and few experiments are simulated(gradient variation, pumping test at different pumping rates and tracer test).

Thesis (Ph.D)--Psychology, Georgia Institute of Technology, 2010.
Committee Chair: Walker, Bruce N.; Committee Member: Corballis, Paul M.; Committee Member: Corso, Gregory M.; Committee Member: Folds, Dennis J.; Committee Member: Houtsma, Adrianus J. M. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Year after year, technologies are evolving in an incredible rapid pace, becoming faster, more complex, more accurate and more immersive. Looking back just a decade, especially interaction technologies have made a major leap. Just two years ago in 2013, after being researched for quite some time, the hype around virtual reality (VR) arouse renewed enthusiasm, finally reaching mainstream attention as the so called head-mounted displays (HMD), devices worn on the head  to grant a visual peek into the virtual world, gain more and more acceptance with the end-user. Currently, humans interact with computers in a very counter-intuitive two dimensional way. The ability to experience digital content in the humans most natural manner, by simply looking around and perceiving information from their surroundings, has the potential to be a major game changer in how we perceive and eventually interact with digital information. However, this confronts designers and developers with new challenges of how to apply these exciting technologies, supporting interaction mechanisms to naturally explore digital information in the virtual world, ultimately overcoming real world boundaries. Within the virtual world, the only limit is our imagination. This thesis investigates an approach of how to naturally interact and explore information based on open data within an immersive virtual reality environment using a head-mounted display and vision-based motion controls. For this purpose, an immersive VR application visualizing information as a network of European capital cities has been implemented, offering interaction through gesture input. The application lays a major focus on the exploration of the generated network and the consumption of the displayed information. While the conducted user interaction study with eleven participants investigated their acceptance of the developed prototype, estimating their workload and examining their explorative behaviour, the additional dialog with five experts in the form of explorative discussions provided further feedback towards the prototype’s design and concept. The results indicate the participants’ enthusiasm and excitement towards the novelty and intuitiveness of exploring information in a less traditional way than before, while challenging them with the applied interface and interaction design in a positive manner. The design and concept were also accepted through the experts, valuing the idea and implementation. They provided constructive feedback towards the visualization of the information as well as emphasising and encouraging to be even bolder, making more usage of the available 3D environment. Finally, the thesis discusses these findings and proposes recommendations for future work.

Este trabalho apresenta diversas propostas associadas ao uso ótimo de funções de transferência relativas à cabeça (HRTFs) em sistemas de reprodução acústica virtual por fones de ouvido. Estas propostas permitem personalizar a HRTF a indivíduos particulares, tomando como base uma combinação da modelagem estrutural e morfológica de HRTFs. Dentro do contexto da modelagem estrutural, o presente trabalho se concentrou no estudo da contribuição do pinna à HRTF. O pinna é a estrutura anatômica responsável pela percepção de elevação. Assim, o primeiro passo foi extrair um conjunto de funções de transferência relativas ao pinna (PRTFs) das HRTFs de uma base de dados. Para tanto, foram usadas diversas técnicas como análise preditiva linear para rastrear as ressonâncias, janelamento para eliminar a influência do torso, funções de autocorrelação e de atraso de grupo para salientar as antirressonâncias, e outros algoritmos para combinar ressonâncias e antirressonâncias em apenas uma magnitude espectral. Usando essa nova base de dados de PRTFs e parâmetros antropométricos propostos mais outros registrados na base de dados, um espaço vetorial correspondente à antropometria do pinna foi mapeado linearmente em um espaço vetorial correspondente às características espectrais da PRTF, calculando-se assim várias transformações lineares para estimação de novas PRTFs fora da base de dados. A estimação atingiu 66% de reconstrução no grupo de treino. O trabalho está orientado à exploração das características espectrais importantes na percepção de elevação, portanto, está limitado ao plano médio do hemisfério frontal, onde não existem diferenças interaurais significativas nem efeitos difrativos da cabeça. Finalmente é proposto um sistema de testes de localização de fonte sonora para validar o modelo.
This work presents several proposals associated with the optimal use of head-related transfer functions (HRTF) in virtual auditory spaces presented via headphones. These proposals lead to personalization of the HRTF to particular individuals, using a combination of the structural and morphological modeling techniques. In the context of structural modeling, this work focuses on modeling the contribution of the pinna to the HRTF. The pinna is the anatomical structure responsible for vertical sound localization. Thus, the first step was to extract a set of pinna-related transfer functions (PRTFs) from HRTFs published in a database. This was accomplished using several techniques like linear prediction analysis for tracking the resonances, windowing for eliminating the torso influence, autocorrelation and group delay functions for emphasizing the notches and other algorithms for combining resonances and notches in only one magnitude response. Using this novel database of PRTFs and a set of proposed anthropometric parameters plus some others registered in the database, a vector space corresponding to pinna anthropometry is linearly mapped into a vector space corresponding to spectral features of the PRTF, being calculated, in this way, several linear transformations for estimation of new PRTFs, outside the database. The estimation attains 66% of reconstruction in the training group. The work focuses on the exploration of spectral characteristics important for elevation perception, therefore, it is limited to the median plane where there are no meaningful interaural differences nor head diffraction effects. Finally, a system for sound localization tests is proposed in order to validate the model.

Abstract The use of 3D imaging of craniofacial soft tissue has increased in medical science, and imaging technology has been developed greatly in recent years. 3D models are quite accurate and with imaging devices based on stereophotogrammetry, capturing the data is a quick and easy operation for the subject. However, analyzing 3D models of the face or head can be challenging and there is a growing need for efficient quantitative methods. In this thesis, new mathematical methods and tools for measuring craniofacial structures are developed. The thesis is divided into three parts. In the first part, facial 3D data of Lithuanian twins are used for the determination of zygosity. Statistical pattern recognition methodology is used for classification and the results are compared with DNA testing. In the second part of the thesis, the distribution of surface normal vector directions of a 3D infant head model is used to analyze skull deformation. The level of flatness and asymmetry are quantified by functionals of the kernel density estimate of the normal vector directions. Using 3D models from infants at the age of three months and clinical ratings made by experts, this novel method is compared with some previously suggested approaches. The method is also applied to clinical longitudinal research in which 3D images from three different time points are analyzed to find the course of positional cranial deformation and associated risk factors. The final part of the thesis introduces a novel statistical scale space method, SphereSiZer, for exploring the structures of a probability density function defined on the unit sphere. The tools developed in the second part are used for the implementation of SphereSiZer. In SphereSiZer, the scale-dependent features of the density are visualized by projecting the statistically significant gradients onto a planar contour plot of the density function. The method is tested by analyzing samples of surface unit normal vector data of an infant head as well as data from generated simulated spherical densities. The results and examples of the study show that the proposed novel methods perform well. The methods can be extended and developed in further studies. Cranial and facial 3D models will offer many opportunities for the development of new and sophisticated analytical methods in the future
Tiivistelmä Pään ja kasvojen pehmytkudoksen 3D-kuvantaminen on yleistynyt lääketieteessä, ja siihen tarvittava teknologia on kehittynyt huomattavasti viime vuosina. 3D-mallit ovat melko tarkkoja, ja kuvaus stereofotogrammetriaan perustuvalla laitteella on nopea ja helppo tilanne kuvattavalle. Kasvojen ja pään 3D-mallien analysointi voi kuitenkin olla haastavaa, ja tarve tehokkaille kvantitatiivisille menetelmille on kasvanut. Tässä väitöskirjassa kehitetään uusia matemaattisia kraniofakiaalisten rakenteiden mittausmenetelmiä ja -työkaluja. Työ on jaettu kolmeen osaan. Ensimmäisessä osassa pyritään määrittämään liettualaisten kaksosten tsygositeetti kasvojen 3D-datan perusteella. Luokituksessa hyödynnetään tilastollista hahmontunnistusta, ja tuloksia verrataan DNA-testituloksiin. Toisessa osassa analysoidaan pään epämuodostumia imeväisikäisten päiden 3D-kuvista laskettujen pintanormaalivektorien suuntiin perustuvan jakauman avulla. Tasaisuuden ja epäsymmetrian määrää mitataan normaalivektorien suuntakulmien ydinestimaatin funktionaalien avulla. Kehitettyä menetelmää verrataan joihinkin aiemmin ehdotettuihin lähestymistapoihin mittaamalla kolmen kuukauden ikäisten imeväisten 3D-malleja ja tarkastelemalla asiantuntijoiden tekemiä kliinisiä pisteytyksiä. Menetelmää sovelletaan myös kliiniseen pitkittäistutkimukseen, jossa tutkitaan pään epämuodostumien ja niihin liittyvien riskitekijöiden kehitystä kolmena eri ajankohtana otettujen 3D-kuvien perusteella. Viimeisessä osassa esitellään uusi tilastollinen skaala-avaruusmenetelmä SphereSiZer, jolla tutkitaan yksikköpallon tiheysfunktion rakenteita. Toisessa osassa kehitettyjä työkaluja sovelletaan SphereSiZerin toteutukseen. SphereSiZer-menetelmässä tiheysfunktion eri skaalojen piirteet visualisoidaan projisoimalla tilastollisesti merkitsevät gradientit tiheysfunktiota kuvaavalle isoviivakartalle. Menetelmää sovelletaan imeväisikäisen pään pintanormaalivektoridataan ja simuloituihin, pallotiheysfunktioihin perustuviin otoksiin. Tulosten ja esimerkkien perusteella väitöskirjassa esitetyt uudet menetelmät toimivat hyvin. Menetelmiä voidaan myös kehittää edelleen ja laajentaa jatkotutkimuksissa. Pään ja kasvojen 3D-mallit tarjoavat paljon mahdollisuuksia uusien ja laadukkaiden analyysityökalujen kehitykseen myöhemmissä tutkimuksissa

Diplomová práce je zaměřena na problematiku detekce a sledování polohy hlavy v obraze jako jednu s možností jak zlepšit možnosti interakce mezi počítačem a člověkem. Hlavním přínosem diplomové práce je využití inovativních hardwarových a softwarových technologií jakými jsou Microsoft Kinect, Point Cloud Library a CImg Library. Na úvod je představeno shrnutí předchozích prací na podobné téma. Následuje charakteristika a popis databáze, která byla vytvořena pro účely diplomové práce. Vyvinutý systém pro detekci a sledování polohy hlavy je založený na akvizici 3D obrazových dat a registračním algoritmu Iterative Closest Point. V závěru diplomové práce je nabídnuto hodnocení vzniklého systému a jsou navrženy možnosti jeho budoucího zlepšení.

La evolución de la tecnología de Realidad Virtual (RV) ha contribuido en todos los campos, incluyendo la psicología. Esta evolución implica mejoras tanto en hardware como en software, que permiten experiencias más inmersivas. En un entorno de RV los usuarios pueden percibir la sensación de "presencia" y sentirse "inmersos". Estas sensaciones son posibles utilizando HMDs. Hoy en día, el desarrollo de los HMDs se ha centrado en mejorar sus características técnicas para ofrecer inmersión total. En psicología, los entornos de RV son una herramienta de investigación. Hay algunas aplicaciones para evaluar la memoria espacial que utilizan métodos básicos de interacción. Sin embargo, sistemas de RV que incorporen estereoscopía y movimiento físico todavía no se han explotado en psicología. En esta tesis, se ha desarrollado un nuevo sistema de RV que combina características inmersivas, interactivas y de movimiento. El sistema de RV (tarea en un laberinto virtual) se ha utilizado para evaluar la memoria espacial y la percepción de profundidad. Se han integrado dos tipos diferentes de interacción: una basada en locomoción que consistió en pedalear en una bicicleta fija (condición1) y otra estacionaria usando un gamepad (condición2). El sistema integró dos tipos de visualización: 1) Oculus Rift (OR); 2) Una gran pantalla estéreo. Se diseñaron dos estudios. El primer estudio (N=89) evaluó la memoria espacial a corto plazo usando el OR y los dos tipos de interacción. Los resultados indican que existían diferencias significativas entre ambas condiciones. Los participantes que utilizaron la condición2 obtuvieron mejor rendimiento que los que utilizaron la tarea en la condición1. Sin embargo, no se encontraron diferencias significativas en las puntuaciones de satisfacción e interacción entre ambas condiciones. El desempeño en la tarea correlacionó con el desempeño en las pruebas neuropsicológicas clásicas, revelando la verosimilitud entre ellas. El segundo estudio (N=59) incluyó participantes con y sin estereopsis. Este estudio evaluó la percepción de profundidad comparando los dos sistemas de visualización. Los participantes realizaron la tarea usando la condición2. Los resultados mostraron que las diferentes características del sistema de visualización no influyeron en el rendimiento en la tarea entre los participantes con y sin estereopsis. Se encontraron diferencias significativas a favor del HMD entre las dos condiciones y entre los dos grupos de participantes respecto a la percepción de profundidad. Los participantes que no tenían estereopsis y no podían percibir la profundidad cuando utilizaban otros sistemas de visualización, tuvieron la ilusión de percepción de profundidad cuando utilizaron el OR. El estudio sugiere que para las personas que no tienen estereopsis, el seguimiento de la cabeza influye en gran medida en la experiencia 3D. Los resultados estadísticos de ambos estudios han demostrado que el sistema de RV desarrollado es una herramienta apropiada para evaluar la memoria espacial a corto plazo y la percepción de profundidad. Por lo tanto, los sistemas de RV que combinan inmersión total, interacción y movimiento pueden ser una herramienta útil para la evaluación de procesos cognitivos humanos como la memoria. De estos estudios se han extraído las siguientes conclusiones generales: 1) La tecnología de RV y la inmersión proporcionada por los actuales HMDs son herramientas adecuadas para aplicaciones psicológicas, en particular, la evaluación de la memoria espacial a corto plazo; 2) Un sistema de RV como el presentado podría ser utilizado como herramienta para evaluar o entrenar adultos en habilidades relacionadas con la memoria espacial a corto plazo; 3) Los dos tipos de interacción utilizados para la navegación en el laberinto virtual podrían ser útiles para su uso con diferentes colectivos; 4) El OR permite que los usuarios sin estereopsis puedan percibir l
The evolution of Virtual Reality (VR) technology has contributed in all fields, including psychology. This evolution involves improvements in hardware and software allowing more immersive experiences. In a VR environment users can perceive the sensation of "presence" and feel "immersed". These sensations are possible using VR devices as HMDs. Nowadays, the development of the HMDs has focused on improving their technical features to offer full immersion. In psychology, VR environments are research tools because they allow the use of new paradigms that are not possible to employ in a real environment. There are some applications for assessing spatial memory that use basic methods of HCI. However, VR systems that incorporate stereoscopy and physical movement have not yet been exploited in psychology. In this thesis, a novel VR system combining immersive, interactive and motion features was developed. This system was used for the assessment of the spatial memory and the evaluation of depth perception. For this system, a virtual maze task was designed and implemented. In this system, two different types of interaction were integrated: a locomotion-based interaction pedaling a fixed bicycle (condition1), and a stationary interaction using a gamepad (condition2). This system integrated two types of display systems: 1) The Oculus Rift; 2) A large stereo screen. Two studies were designed to determine the efficacy of the VR system using physical movement and immersion. The first study (N=89) assessed the spatial short term memory using the Oculus Rift and the two types of interaction The results showed that there were statistically significant differences between both conditions. The participants who performed the condition2 got better performance than participants who performed the condition1. However, there were no statistically significant differences in satisfaction and interaction scores between both conditions. The performance on the task correlated with the performance on other classical neuropsychological tests, revealing a verisimilitude between them. The second study (N=59) involved participants who had and who had not stereopsis. This study assessed the depth perception by comparing the two display systems. The participants performed the task using the condition2. The results showed that the different features of the display system did not influence the performance on the task between the participants with and without stereopsis. Statistically significant differences were found in favor of the HMD between the two conditions and between the two groups of participants regard to depth perception. The participants who did not have stereopsis and could not perceive the depth when they used other display systems (e.g. CAVE); however, they had the illusion of depth perception when they used the Oculus Rift. The study suggests that for the people who did not have stereopsis, the head tracking largely influences the 3D experience. The statistical results of both studies have proven that the VR system developed for this research is an appropriate tool to assess the spatial short-term memory and the depth perception. Therefore, the VR systems that combine full immersion, interaction and movement can be a helpful tool for the assessment of human cognitive processes as the memory. General conclusions from these studies are: 1) The VR technology and immersion provided by current HMDs are appropriate tools for psychological applications, in particular, the assessment of spatial short-term memory; 2) A VR system like the one presented in this thesis could be used as a tool to assess or train adults in skills related to spatial short-term memory; 3) The two types of interaction (condition1 and condition2) used for navigation within the virtual maze could be helpful to use with different collectives; 4) The Oculus Rift allows that the users without stereopsis can perceive the depth perception of 3D objects and have rich 3D experiences.
L'evolució de la tecnologia de Realitat Virtual (RV) ha contribuït en tots els camps, incloent la psicologia. Aquesta evolució implica millores en el maquinari i el programari que permeten experiències més immersives. En un entorn de RV, els usuaris poden percebre la sensació de "presència" i sentir-se "immersos". Aquestes sensacions són possibles utilitzant HMDs. Avui dia, el desenvolupament dels HMDs s'ha centrat a millorar les seves característiques tècniques per oferir immersió plena. En la psicologia, els entorns de RV són eines de recerca. Hi ha algunes aplicacions per avaluar la memòria espacial que utilitzen mètodes bàsics d'interacció. Tanmateix, sistemes de RV que incorporen estereoscòpia i moviment físic no s'han explotat en psicologia. En aquesta tesi, s'ha desenvolupat un sistema de RV novell que combina immersió, interacció i moviment. El sistema (tasca en un laberint virtual) s'ha utilitzat per a l'avaluació de la memòria espacial i la percepció de profunditat. S'han integrat dos tipus d'interacció: una interacció basada en locomoció pedalejant una bicicleta fixa (condició1), i l'altra una interacció estacionària usant un gamepad (condició2). S'han integrat dos tipus de sistemes de pantalla: 1) L'Oculus Rift; 2) Una gran pantalla estereoscòpica. Dos estudis van ser dissenyats. El primer estudi (N=89) va avaluar la memòria a curt termini i espacial utilitzant l'Oculus Rift i els dos tipus d'interacció. Els resultats indiquen que hi havia diferències significatives entre les dues condicions. Els participants que van utilitzar la condició2 van obtenir millor rendiment que els participants que van utilitzar la condició1. Tanmateix, no hi havia diferències significatives dins satisfacció i puntuacions d'interacció entre les dues condicions. El rendiment de la tasca va correlacionar amb el rendiment en les proves neuropsicològiques clàssiques, revelant versemblança entre elles. El segon estudi (N=59) va implicar participants que van tenir i que van haver-hi no estereopsis. Aquest estudi va avaluar la percepció de profunditat comparant els dos sistemes de pantalla. Els participants realitzen la tasca utilitzant la condició2. Els resultats van mostrar que les diferents característiques del sistema de pantalla no va influir en el rendiment en la tasca entre els participants qui tenien i els qui no tenien estereopsis. Diferències significatives van ser trobades a favor del HMD entre les dues condicions i entre els dos grups de participants. Els participants que no van tenir estereopsis i no podien percebre la profunditat quan van utilitzar altres sistemes de pantalla (per exemple, CAVE), van tenir la il.lusió de percepció de profunditat quan van utilitzar l'Oculus Rift. L'estudi suggereix que per les persones que no van tenir estereopsis, el seguiment del cap influeix en gran mesura en l'experiència 3D. Els resultats estadístics dels dos estudis han provat que el sistema de RV desenvolupat per aquesta recerca és una eina apropiada per avaluar la memòria espacial a curt termini i la percepció de profunditat. Per això, els sistemes de RV que combinen immersió plena, interacció i moviment poden ser una eina útil per la avaluació de processos cognitius humans com la memòria Les conclusions generals que s'han extret d'aquests estudis, són les següents: 1) La tecnologia de RV i la immersió proporcionada pels HMDs són eines apropiades per aplicacions psicològiques, en particular, la avaluació de memòria espacial a curt termini; 2) Un sistema de RV com el presentat podria ser utilitzat com a eina per avaluar o entrenar adults en habilitats relacionades amb la memòria espacial a curt termini; 3) Els dos tipus d'interacció utilitzats per navegació dins del laberint virtual podrien ser útils per al seu ús amb diferent col.lectius; 3) L'Oculus Rift permet que els usuaris que no tenen estereopsis puguen percebre la percepció de profunditat dels objectes 3D i tenir
Cárdenas Delgado, SE. (2017). VR systems for memory assessment and depth perception [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/94629
TESIS

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2008.
Includes bibliographical references.

L'objectiu d'aquesta tesi és l'estudi de les diferents tècniques per alinear vistes tridimensionals. Aquest estudi ens ha permès detectar els principals problemes de les tècniques existents, aprotant una solució novedosa i contribuint resolent algunes de les mancances detectades especialment en l'alineament de vistes a temps real. Per tal d'adquirir les esmentades vistes, s'ha dissenyat un sensor 3D manual que ens permet fer adquisicions tridimensionals amb total llibertat de moviments. Així mateix, s'han estudiat les tècniques de minimització global per tal de reduir els efectes de la propagació de l'error.
The goal of this thesis is to study the different techniques used to register 3D acquisitions. This study detects the main drawbacks of the existing techniques, presents a new classification and provides significant solutions of some perceived shortcomings, especially in 3D real time registration. A 3D hand-held sensor has been designed to acquire these views without any motion restriction and global minimization techniques have been studied to decrease the error propagation effects.