Dissertations / Theses on the topic 'Digital terrain modeling'

Thesis (M.S. in Modeling, Virtual Environments, and Simulation (Moves))--Naval Postgraduate School, March 2006.
Thesis Advisor(s): Wolfgang Baer, Curtis L. Blais. "March 2006." Includes bibliographical references (p.99-101). Also available online.

The spatial patterns of land surface and subsurface characteristics determine the spatial heterogeneity of hydrological processes. Soil depth is one of these characteristics and an important input parameter required by distributed hydrological models that explicitly represent spatial heterogeneity. Soil is related to topography and land cover due to the role played by topography and vegetation in affecting soil-forming processes. The research described in this dissertation addressed the development of statistical models that predict the soil depth pattern over the landscape; derivation of new topographic variables evaluated using both serial and parallel algorithms; and evaluation of the impacts of detailed soil depth representation on simulations of stream flow and soil moisture. The dissertation is comprised of three papers. In paper 1, statistical models were developed to predict soil depth pattern over the watershed based on topographic and land cover variables. Soil depth was surveyed at locations selected to represent the topographic and land cover variation at the Dry Creek Experimental Watershed, near Boise, Idaho. Explanatory variables were derived from a digital elevation model and remote sensing imagery for regression to the field data. Generalized Additive and Random Forests models were developed to predict soil depth over the watershed. The models were able to explain about 50% of the soil depth spatial variation, which is an important improvement over the soil depth extracted from the SSURGO national soil database. In paper 2, definitions of the new topographic variables derived in the effort to model soil depth, and serial and Message Passing Interface parallel implementations of the algorithms for their evaluation are presented. The parallel algorithms enhanced the processing speed of large digital elevation models as compared to the serial recursive algorithms initially developed. In paper 3, the impact of spatially explicit soil depth information on simulations of stream flow and soil moisture as compared to soil depth derived from the SSURGO soil database has been evaluated. The Distributed Hydrology Vegetation Soil Model was applied using automated parameter optimization technique with all input parameters the same except soil depth. Stream flow was less impacted by the detailed soil depth information, while simulation of soil moisture was slightly improved due to the detailed representation of soil depth.

Analisi generale della struttura e realizzazione dei file DTM, del campionamento dei dati atti alla realizzazione dei modelli digitali del terreno e panoramica sull'applicazione dei DTM nelle varie discipline.

The simple accumulation-based network identification method (ANIM) in a raster Geographic Information System (GIS) posed by Oâ Callaghan and Mark (1984) has been criticized for producing a spatially uniform drainage density (Tarboton 2002) at the watershed scale. This criticism casts doubt on the use of ANIMs for deriving properties such as overland flow length for nonpoint source pollution models, without calibrating the accumulation threshold value. However, the basic assumption that underlies ANIMs is that convergent topography will yield a more rapid accumulation of cells, and thus, more extensive flow networks, with divergent, or planar terrain yielding sparser networks. Previous studies have focused on networks that are coarser than the hill-slope scale, and have relied upon visual inspection of drainage networks to suggest that ANIMs lack the ability to produce diverse networks. In this study overland flow lengths were calculated on a sub-watershed basis, with standard deviation, and range calculated for sub-watershed populations as a means of quantifying the diversity of overland flow lengths produced by ANIM at the hill slope scale. Linear regression and Spearman ranking analyses were used to determine if the methods represented trends in overland flow length as suggested by manual delineation of contour lines. Three ANIMs were analyzed: the flow accumulation method (Oâ Callaghan and Mark, 1984), the terrain curvature method (Tarboton, 2000) and the ridge accumulation method (introduced in this study). All three methods were shown to produce non-zero standard deviations and ranges using a single support area threshold, with the terrain curvature method producing the most diverse networks, followed by the ridge accumulation method, and then the flow accumulation method. At an analysis unit size of 20 ha, the terrain curvature method produced a standard deviation that was most similar to those suggested by the contour crenulations, -13.5%, followed by the ridge accumulation method, -21.5%, and the flow accumulation method, -61.6%. The ridge accumulation produced the most similar range, -19.1%, followed by terrain curvature, -24.9%, and flow accumulation, -65.4%. While the flow accumulation networks had a much narrower range of predicted flow lengths, it had the highest Spearman ranking coefficient, Rs=0.722, and linear regression coefficient, R2=0.602. The terrain curvature method was second, Rs=0.641, R2=0.469, and then ridge accumulation, Rs=0.602, R2=0.490. For all methods, as threshold values were varied, areas of dissimilar morphology (as evidenced by the common stream metric stream frequency) experienced changes in overland flow lengths at different rates. This results in an inconsistency in ranking of sub-watersheds at different thresholds. When thresholds were varied to produce average overland flow lengths from 75 m to 150 m, the terrain curvature method showed the lowest incidence of rank change, 16.05%, followed by the ridge accumulation method, 16.73%, then flow accumulation, 25.18%. The results of this investigation suggest that for all three methods, a causal relationship exists between threshold area, underlying morphology, and predicted overland flow length. This causal relationship enables ANIMs to represent contour network trends in overland flow length with a single threshold value, but also results in the introduction of rank change error as threshold values are varied. Calibration of threshold value (varying threshold in order to better match observed overland flow lengths) is an effective means of increasing the accuracy of ANIM predictions, and may be necessary when comparing areas with different stream frequencies. It was shown that the flow accumulation method produces less diverse networks than the terrain curvature and ridge accumulation methods. However, the results of rank and regression analyses suggest that further investigation is required to determine if these more diverse ANIM are in fact more accurate than the flow accumulation method.
Master of Science

La télédétection ouvre des perspectives nouvelles pour l’étude et la surveillance des volcans. Dans le cadre de cette thèse, différentes approches ont été abordées. L’imagerie satellite optique et thermique permet d’avoir une vue synoptique sur une large surface. La compréhension des changements d’état de surface est particulièrement importante dans le suivi de l’activité des volcans actifs. Plusieurs questions se posent : • Quels avantages offrent les satellites optiques d’observation de la Terre pour les calculs des volumes de lave émis ? • Quelles sont leurs limites ? • Les calculs de débits réalisés par télédétection sont-ils fiables ? • Quel est l’intérêt d’une approche multi-outils et multi-source ? Ces questions ont été abordées en prenant le Piton de la Fournaise pour cible. Plusieurs méthodes ont été mises en oeuvre et testées : 1) L’extraction automatique des contours de coulées de lave, 2) la création de modèle numérique d’élévation (MNE) par imagerie satellite, 3) le calcul de débits à partir d’images thermiques, 4) le suivi post éruptif d’une coulée par la modélisation de son refroidissement et la mesure des déformations observées in-situ. La plus-value de ce travail est la capacité de valider les résultats des modèles issus de la télédétection par des mesures in situ du fait de la proximité des sites étudiés. L’utilisation de ces techniques a permis d’obtenir des débits moyens d’écoulement des laves pour plusieurs éruptions et de suivre l’évolution topographique du volcan et de ses grandes structures. Les mesures thermiques par satellite fournissent le moyen de contraindre les variations du débit des éruptions dans le temps, tandis que les MNE ont permis d’obtenir un volume total dans le cas de coulées présentant de fortes épaisseurs. Grâce à ces techniques, il a été possible de définir deux types d’éruptions avec des évolutions semblables à celles observées sur différents volcans comme l’Etna (Italie) ou le Krafla (Islande). Les problèmes de nébulosité étant récurrent sur notre zone d’étude, la complémentarité des techniques est particulièrement intéressante pour obtenir une information fiable. Toutes les techniques utilisées dans cette thèse sont applicables à d’autres volcans ou à d’autres thématiques
Remote sensing opens new perspectives for the study and monotoring of volcanoes. In this thesis, different approaches were discussed. optical and thermal satellite imagery provides a synoptic view over a wide area. The understanding of surface state changes is particulary important in the monotoring of the activity of active volcanoes. Several, questions arise: • What advantages offer optical observation satellites of the Earth for calculations of lava volumes issues? • What are their limits? • Calculations of flow by remote sensing are reliable? • What is the interest of a multi-tool and multi-source approach? These issues were addressed by taking the Piton de la Fournaise to target. Several methods have been implemented and tested: 1) automatic extraction of the contours of flows of lava, 2) the cretion of numerical model of elevation (DEM) imaging satellite, 3) the calculation of flows from thermal images, 4) follow-up post eruptive flow modelling of cooling and the observed deformations in-situ measurement. The added value of this work is the ability to validate the results of remote sensing measurements from models because of the proximity of the sites studied in situ. The use of these techniques to obtain the average flow rates of lavas to several eruptions and follow topographic evolution of the volcano and its large structures. Satellite thermal measurements provide the means of forcing changes in the flow of eruptions over time, while Dems helped to obtain a total volume in the case of flows with high thicknesses. With these techniques, it was possible to define two types of erutions with changes similar to those observed on different volcanoes

O presente trabalho consistiu no estudo de uma série de atributos do meio físico, como geologia, pedologia, materiais inconsolidados, declividade e menor extensão do percurso da água superficial, entre outros, representados na escala 1:50.000 referentes às bacias hidrográficas dos rios Passa Cinco e Cabeça. Tais atributos foram avaliados, considerando as restrições e potencialidades do meio, buscando uma melhor elaboração das propostas e procedimentos adotados na manutenção da qualidade do meio físico. Para a realização deste estudo, foram utilizados trabalhos já desenvolvidos na área, assim como novos mapas e cartas elaborados durante este, seguindo-se os conceitos da cartografia geoambiental, voltados ao planejamento, proteção e recuperação territorial. Para agilizar os trabalhos de manipulação (armazenamento, recuperação, tratamento, cruzamento e apresentação), foi utilizado um Sistema de Informação Geográfica (SIG-IDRISI), principalmente para obtenção das cartas de Susceptibilidade à Erosão, Potencial à Infiltração e Potencial Agrícola. O resultado final permitiu a obtenção da Carta de Comportamento do Meio Físico como Base para o Zoneamento Geoambiental, onde estão presentes as aptidões, restrições e conflitos de uso, considerando-se neste caso todos os atributos já comentados anteriormente.
Many attributes of the Passa Cinco and Cabeça river hydrographic basins, related to geology, pedology, unconsolidated materials, slope and least water runoff distance, at a 1:50,000 scale, were evaluated. Such attributes based on adequated proposal and procedures were assessed in terms of constraints to determine the basin potentialities. Geoenvironmental cartographic concepts related to planning, protection and management, have been applied in the develop of the charts and maps presented in this works, which, in turn, were base on the extensive research already done in this area. The GIS IDRISI was used to handle data (storing, retrieving, treatment, overlaying and presentation), mainly to elaborate the charts of Erosion Susceptibility, Water lnfiltration Potential and Agricultural Potential. As final result, this work presents an analysis of the environmental attributes to orientate the geoenvironmental zoning, considering all the aspects mentioned above.

Analysis of digital elevation models (DEMs) by means of geomorphometry provides means of recognising fractures and characterising the morphotectonics of an area in a quantitative way. The objective of the thesis is to develop numerical methods and a consistent GIS methodology for tectonic geomorphology and apply it to test sites. Based on the study of landforms related to faults, geomorphological characteristics are translated into mathematical and numerical algorithms. The methodology is based on general geomorphometry. In this study, the basic geometric attributes (elevation, slope, aspect and curvatures) are complemented with the automatic extraction of ridge and valley lines and surface specific points. Evan’s univariate and bivariate methodology of general geomorphometry is extended with texture (spatial) analysis methods such as trend, autocorrelation, spectral, wavelet and network analysis. Digital terrain modelling is carried out by means of (1) general geomorphometry, (2) digital drainage network analysis, (3) digital image processing, (4) lineament extraction and analysis, (5) spatial and statistical analysis and (6) DEM specific digital methods such as shaded relief models, digital cross-sections and 3D surface modelling. Geological data of various sources and scales are integrated in a GIS database. Interpretation of multi-source information confirmed the findings of digital morphotectonic investigation. A simple shear model with principal displacement zone in the NE-SW direction can explain most of the morphotectonic features associated with structures identified by geological and digital morphotectonic investigations in the Kali Basin. Comparison of the results of the DTA with the known geology from NW Greece indicated that the major faults correspond to clear lineaments. Thus, DTA of an area in the proposed way forms a useful tool to identify major and minor structures covering large areas. In this thesis, numerical methods for drainage network extraction and aspect analysis have been developed and applied to tectonic geomorphology.

Terrain surfaces conserve human activities in terms of textures and structures. With reference to archaeological questions, the geological archive is investigated by means of models regarding anthropogenic traces. In doing so, the high-resolution digital terrain model is of inestimable value for the decoding of the archive. The evaluation of these terrain models and the reconstruction of historical surfaces is still a challenging issue. Due to the data collection by means of LiDAR systems (light detection and ranging) and despite their subsequent pre-processing and filtering, recently anthropogenic artefacts are still present in the digital terrain model. Analysis have shown that elements, such as contour lines and channels, can well be extracted from a highresolution digital terrain model. This way, channels in settlement areas show a clear anthropogenic character. This fact can also be observed for contour lines. Some contour lines representing a possibly natural ground surface and avoid anthropogenic artefacts. Comparable to channels, noticeable patterns of contour lines become visible in areas with anthropogenic artefacts. The presented work ow uses functionalities of ArcGIS and the programming language R.¹ The method starts with the extraction of contour lines from the digital terrain model. Through macroscopic analyses based on geomorphological expert knowledge, contour lines are selected representing the natural geomorphological character of the surface. In a first step, points are determined along each contour line in regular intervals. This points and the corresponding height information which is taken from an original digital terrain model is saved as a point cloud. Using the programme library gstat, a variographic analysis and the use of a Kriging-procedure based on this follow. The result is a digital terrain model filtered considering geomorphological expert knowledge showing no human degradation in terms of artefacts, preserving the landscape-genetic character and can be called a prehistoric terrain model.

Computer-aided tools appropriate to architecture, engineering and construction have been Summarised, including digital terrain modelling (DTM), computer-aided design and draughting (CADD) and database management systems (DBMS). DTM and CADD techniques have been applied to simulating the hydraulic filling of tailings, or mine waste dams. A relational DBMS was used to structure and manage filling and terrain data relevant to hydraulic tailings disposal at the Wheal Jane mine in Cornwall.

The scale-bound view of landsurfaces, being an assemblage of certain landforms, occurring within limited scale ranges, has been challenged by the scale-free characteristics of fractal geometry. This thesis assesses the fractal model by examining the irregularity of landsurface form, for the self-affine behaviour present in fractional Brownian surfaces. Different methods for detecting self-affine behaviour in surfaces are considered and of these the variogram technique is shown to be the most effective. It produces the best results of two methods tested on simulated surfaces, with known fractal properties. The algorithm used has been adapted to consider log (altitude variance) over a sample of log (distances) for: complete surfaces; subareas within surfaces; separate directions within surfaces. Twenty seven digital elevation models of landsurfaces arc re-examined for self- affine behaviour. The variogram results for complete surfaces show that none of these are self-affine over the scale range considered. This is because of dominant slope lengths and regular valley, spacing within areas. For similar reasons subarea analysis produces the non-fractal behaviour of markedly different variograms for separate subareas. The linearity of landforms in many areas, is detected by the variograms for separate directions. This indicates that the roughness of landsurfaces is anisotropic, unlike that of fractal surfaces. Because of difficulties in extracting particular landforms from their landsurfaces, no clear links between fractal behaviour, and landform size distribution could be established. A comparative study shows the geomorphometric parameters of fractal surfaces to vary with fractal dimension, while the geomorphometry of landsurfaces varies with the landforms present. Fractal dimensions estimated from landsurfaces do not correlate with geomorphometric parameters. From the results of this study, real landsurfaces would not appear to be scale- free. Therefore, a scale-bound approach towards landsurfaces would seem to be more appropriate to geomorphology than the fractal alternative.

As curvas de nível são extremamente úteis na solução dos problemas da engenharia e algumas áreas de aplicação são: topografia, exploração de minérios e petróleo, estudo de campos magnéticos, metrologia e outros. Tem-se recorrido ao auxílio do computador para desenhar automaticamente esse tipo de mapas e são muitos os programas desenvolvidos com essa finalidade. Escolhemos como ponto de partida de nosso estudo um método, de comprovadas qualidades, desenvolvido por Hiroshi Akima: \"A Method of bivariate interpolation and smooth surface fitting for irregularly distributed data points\". A nossa contribuição a esse trabalho consiste na redução do tempo de computação, na melhoria da qualidade do desenho e na adaptação do sistema para uso em microcomputadores, com a consequente redução do custo da produção de mapas.Com o programa de Akima não fornece rotinas de desenho, nós implementamos uma com esse propósito e esta é uma outra contribuição desta tese.
Contour maps are extremely useful in the solution of engineering problems and some areas of applications are: survey, minerals and petroleum exploration, study of magnetic fields , metereology and others. The computer has been used for drawing automatically such maps and there are already several programs developed with this purpose. We have selected as starting point of our study, a method with proved qualities, developed by Hiroshi Akima, entitled: \"A method of bivariate interpolation and smooth surface fitting for irregularly distributed data points\". Our contribution to the work of Akima consists in reducing the computing time, improving the visual aspect of the map and in adapting the system to the use in microcomputers, with the consequent reduction of the cost of map\'s production. Since Akima\'s program does not provide any routine for drawing maps, we further implement one for such purpose and this is another contribution of this thesis.

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Located on the mid-region of Rio Grande do Sul, the watershed of the Arroio Grande lies on the transition of the Central Depression to the Southern Plateau. Belonging to the geographic micro-region of Santa Maria, the watershed area partially covers four municipal districts: Silveira Marins, Itaara, Santa Maria and Júlio de Castilhos. Studies on the area showed, on the last two decades, a local increase tendency of the forest areas, rural activities and a decrease of the field areas. This work had as objective, modeling the dynamics of use and covering of land occurred in two periods of time: from 1991 to 2002 and from 2002 to 2011; and to perform the simulation of scenarios until the year of 2020. To elaborate the thematic maps of land cover and use, images the satellites Landsat 5 and Landsat 7 were classified. The modeling process was performed by the Dinamica EGO app through these methods: Markov Chain, Weights-of-Evidence and Cellular Automata. The simulated maps to the years of 2002 e 2011, when compared with real maps, reached satisfactory similarities indexes. The simulated scenery for the year of 2020 presented significant less percentages of changing of the use and cover than those verified for the previous periods, predicting increase of 2,64% and 4,38% to the forest and rural areas respectively, and a decrease of the field areas about 8,19%. This dynamic may indicate stagnation in the agricultural cultivation areas, because there are no great extensions of proper land for the agricultural advance, which is the main propeller of the observed evolution in the study period, on the regions of greater agricultural vocation, as it is on the proximities of Silveira Martins, in the floodplain of Arroio Grande and in Southern Plateau areas, corresponding to Júlio de Castilhos.
Situada na região central do Rio Grande do Sul, a bacia do Arroio Grande localiza-se na transição da Depressão Central para o Planalto Meridional. Pertencendo a microrregião geográfica de Santa Maria, a área da bacia abrange parcialmente quatro municípios: Silveira Martins, Itaara, Santa Maria e Júlio de Castilhos. Estudos realizados na área evidenciaram, nas últimas duas décadas, uma tendência local de aumento das áreas florestais e das atividades agrícolas e a diminuição das áreas de campo. Este trabalho teve como objetivo modelar a dinâmica de uso e cobertura da terra ocorrida em dois períodos de tempo: 1991- 2002 e 2002-2011, e realizar a simulação de cenários até o ano de 2020. Para elaboração dos mapas temáticos de uso e cobertura da terra foram classificadas imagens dos sensores TM e ETM+ dos satélites Landsat 5 e Landsat 7. O processo de modelagem foi realizado no aplicativo Dinamica EGO através dos métodos: Cadeias de Markov, Pesos de Evidência e Autômatos Celulares. Os mapas simulados para os anos de 2002 e 2011, quando comparados com os mapas reais, alcançaram índices de similaridade satisfatórios. O cenário simulado para o ano de 2020 apresentou percentuais de mudanças de uso e cobertura significativamente menores do que os verificados para os períodos anteriores, prevendo aumentos de 2,64% e 4,38%, para as áreas florestais e agrícolas, respectivamente, e uma diminuição das áreas de campo na ordem de 8,19%. Esta dinâmica pode indicar uma estagnação nas áreas de cultivo agrícola, pois não há grandes extensões de terra adequadas para o avanço da agricultura, principal propulsor da evolução observada no período de estudo, nas regiões com maior vocação agrícola, como nas proximidades de Silveira Martins, nas várzeas do Arroio Grande e em áreas do planalto meridional, correspondentes a Júlio de Castilhos.

Since the beginning of the digital TV in Brazil that the expression interactivity is even more present in our lives. Understanding how the viewer behaves in front of the TV is the aim of many surveys in different areas. Therefore, thinking about the need to understand the interactive behavior of the viewer or the whole population in front of the TV, and also evaluating the evolution of the tools that allow the interactivity, this research suggests the map of the interactivity, registering all the reactions of the viewer in front of the TV and storing it in the set-top box. After gathering all this data we suggest an evaluation by modeling expressed in the underlying graph to the teoria de questionários written by Picard in sixties
Desde a implantação da Televisão Digital no Brasil que o termo interatividade ficou ainda mais presente. Entender como o telespectador comporta-se diante da televisão é objeto de estudo em diversas áreas. Assim, pensando na necessidade de entender o comportamento interativo do telespectador ou de uma população diante da televisão, e avaliando a evolução das ferramentas que proporcionam a interatividade, este trabalho propõe o mapeamento da interatividade, com o registro de todos os passos do telespectador diante da televisão e armazenado em seu set-top box. Com estes registros propõe-se uma avaliação dos dados por meio de uma modelagem expressa em forma de grafos subjacentes à teoria de questionários descrita por Picard nos anos sessenta

Trabalho de Projecto de Mestrado em Ciências de Comunicação Variante Novos Media e Práticas Web
O presente estudo inicia-se com a contextualização histórica da evolução estrutural e formal do Mapa. São analisados os componentes que contribuíram para a formulação do paradigma do mapa do século XX. Com a viragem do Milénio, o paradigma é confrontado com alterações significativas no campo da tecnologia e da sociedade, não previsto no sistema anterior. É identificado o enquadramento actual segundo os eventos que estão a influenciar uma nova perspectiva sobre os sistemas de informação geográficos e são identificados os fenómenos que, por sua vez, estão a pressionar a necessidade de reformulação basilar do paradigma. Uma vez que o mapa é o reflexo do mundo, é necessário compreender qual o modelo correspondente ao século XXI. Dentro deste objectivo são apresentadas abordagens conceptuais que visam propostas sinergéticas com vista à construção do equilíbrio entre o Homem e o Planeta. O trabalho termina com a proposta de linhas guia para o desenho do mapa do século XXI. São identificados os componentes que o novo modelo de mapa deve integrar e é proposto um novo conceito de interface: Human-Computer-Metamorfosis-Interaction (HCMI).

3D environment reconstruction has received great interest in recent years in areas such as city planning, virtual tourism and flood hazard warning. With the rapid development of computer technologies, it has become possible and necessary to develop new methodologies and techniques for real time simulation for virtual environments applications. This thesis proposes a novel dynamic simulation scheme for flood hazard warning. The work consists of three main parts: digital terrain modelling; 3D environmental reconstruction and system development; flood simulation models. The digital terrain model is constructed using real world measurement data of GIS, in terms of digital elevation data and satellite image data. An NTSP algorithm is proposed for very large data assessing, terrain modelling and visualisation. A pyramidal data arrangement structure is used for dealing with the requirements of terrain details with different resolutions. The 3D environmental reconstruction system is made up of environmental image segmentation for object identification, a new shape match method and an intelligent reconstruction system. The active contours-based multi-resolution vector-valued framework and the multi-seed region growing method are both used for extracting necessary objects from images. The shape match method is used with a template in the spatial domain for a 3D detailed small scale urban environment reconstruction. The intelligent reconstruction system is designed to recreate the whole model based on specific features of objects for large scale environment reconstruction. This study then proposes a new flood simulation scheme which is an important application of the 3D environmental reconstruction system. Two new flooding models have been developed. The first one is flood spreading model which is useful for large scale flood simulation. It consists of flooding image spatial segmentation, a water level calculation process, a standard gradient descent method for energy minimization, a flood region search and a merge process. The finite volume hydrodynamic model is built from shallow water equations which is useful for urban area flood simulation. The proposed 3D urban environment reconstruction system was tested on our simulation platform. The experiment results indicate that this method is capable of dealing with complicated and high resolution region reconstruction which is useful for many applications. When testing the 3D flood simulation system, the simulation results are very close to the real flood situation, and this method has faster speed and greater accuracy of simulating the inundation area in comparison to the conventional flood simulation models

Šiame darbe nagrinėjama panoraminio vaizdo tyrimo metodikos ir taikymo problematika. Aptariami pagrindiniai algoritmai naudojami ArcGIS programoje. Darbe pateikiama keletas pavyzdžių, kaip panoraminio vaizdo tyrimai taikant GIS programinę įrangą yra pritaikomi praktikoje. Antroje darbo dalyje yra atliekamas tyrimas, kurio tikslas išsiaiškinti, ar racionalu ir reikalinga būtų taikyti panoraminio matomumo tyrimus žemėlapyje, nekilnojamo turto reklama užsiimančiuose interneto puslapiuose. Tyrimo rezultatai atskleidžia, kad vietovės vaizdingumas yra svarbus veiksnys renkantis nekilnojamą turtą, o žmonės yra pasiruošę naudotis naujomis žemėlapio funkcijomis suteikiančiomis daugiau galimybių atliekant nekilnojamo turto vertinimą, tačiau panoraminio matomumo įrankio diegti į sistemas nerekomenduojama, dėl darbe aptariamų šios funkcijos trūkumų. Kita vertus autorius siūlo diegti naujas funkcijas, kurios pagerintų nešališką nekilnojamo turto vertinimą.
Work is developing the problem of methodology and applications of viewshed. Author is writing about main algorithms of this GIS function in ArcGIS program. Few practicable applications of viewshed are presented at work also. Item, some problems of these algorithms and applications of viewshed are developing. In second part of work author presents research about applications of viewshed for the internet web sites where is presented commercial of realty. The result consequent upon the research said that visibility is one of the main criterions of realty. Also Purchasers are ready for innovations of geographical information systems. On the other hands realty needs new GIS and mapping applications. In the conclusion of work author says that it is not worth to add the tool if viewshed to GIS systems to web pages of commercial of realty, because this tool have some problems for applications. On the other hand author suggests add some other functions to these maps which will improve neutral evaluation of realty.

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This study aims to evaluate the altimetric accuracy of Digital Surface Models - DSM and generation of a DSM composed using scene taken by PRISM Sensor - Panchromatic Remote Sensing Instrument for Stereo Mapping (viewing directions Backward, Forward and Nadir) which is located aboard the ALOS satellite (Advanced Land Observing Satellite). The Toutin Model is used to perform on the realization of geometric correction of images, were that took into account the influence of the number of control points and tie points for generation of DSMs. There were generated 54 models divided into four tests which look forward to determinate the minimum number of tie points to be used for the generation of DSM (test 01), the adequacy of the methodology proposed by IBGE (2009) for the region studied, whose relief has different characteristics employed by this agency (test 02), the influence of increasing the number of control points on the altimetric quality DSMs (test 03) and the effect of the combination of the three viewing directions behavior and the use of different strategies of correlation between images and spatial resolution of the models in the final products accuracy (test 04). The DSM derived from each test were evaluated by use of the Decree-Law 89.817/1984 and those which recieved better ratings were submitted to a local analysis, where it was investigated the behavior of the altitude values using the PEC for an area located in Viçosa and a empirical analysis was employed, in order to verify the behavior of pixels located regions that had shades of vegetation and cloud shadows using for that the correlation coefficient of epipolar pairs generated for each DSM besides conducting analysis of the effects of slope on the quality altimetric using as base the correlation coefficient. The DSMs that showed better results after the use of all these tests were used for the orthorectification of the Nadir scene and orthoimages, were evaluated globally using the PEC and the local way, in order to verify the influence of radiometric resolution on the vectorization of orthoimage. The DSM used for orthorectification also underwent a final examination, which took place a refinement in their altitude values by employing the Koppe s Formula modified by Kraus (2004) that takes into account the influence of slope and the scale factor when taken on the scenes of aerial images which led to a Composed DSM consisted of all pixels that presented a lower standard deviation. The results revealed that the PRISM sensor allows to obtain DSMs of consistent standards for the National Mapping Scale 1:25.000, with the need to use a minimum number of seven control points associated with twelve tie points and use of viewing directions Backward x Nadir for the generation of models. The increase in the number of control points to perform the correction using the geometric Toutin model did not bring significant improvements to the quality of altimetric DSMs evaluated, although they showed the best results were those that used 60 control points in their generation. The methodology proposed by IBGE (2009) proved to be applicable to regions with similar characteristics to those studied in this work, although there is a need for testing in areas with similar characteristics studied. Using the Koppe s Formula modified was satisfactory, allowing to associate in a single DSM the lowest indicative altimetric errors found for the altimetric component, and the results were superior to the other models evaluated. The orthoimages obtained are classified in Class A of the Decree-Law for the scale of 1:25.000, however due to the low radiometric resolution of the scenes PRISM (8 bits) the extraction process of physical elements, especially in urban areas, become difficult to interpret.
O presente trabalho tem como objetivo a avaliação da acurácia altimétrica de Modelos Digitais de Superfície (MDSs) e geração de MDSs compostos, utilizando a cena tomada pelo Sensor PRISM - Panchromatic Remote Sensing Instrument for Stereo Mapping no modo triplet (visadas Backward, Nadir e Forward) que se encontra a bordo do Satélite ALOS (Advanced Land Observing Satellite). Para realização da Correção Geométrica das imagens foi empregado o Modelo de Toutin. Foram gerados 54 MDSs divididos em quatro testes, que procuraram verificar o número mínimo de pontos de ligação a serem utilizados para geração de cada MDS, a adequação da Metodologia proposta por IBGE (2009) a uma região, cujo relevo possui características diferentes da estudada por este órgão, a influência do aumento do número de pontos de controle na qualidade altimétrica dos MDSs e a combinação das três visadas associadas ao uso de diferentes estratégias de correlação entre imagens e resolução espacial dos modelos. Os MDSs resultantes de cada teste foram avaliados através do emprego do Decreto-Lei 89.817/1984 que institui o Padrão de Exatidão Cartográfica PEC e aqueles que obtiveram melhor classificação foram submetidos a uma análise local, onde se verificou o comportamento dos valores de altitude empregando o PEC para uma área situada no município de Viçosa, bem como realizada uma análise empírica, com a finalidade de verificar o comportamento dos pixels situados em regiões que apresentavam sombras da vegetação e sombras de nuvens, utilizando para isso, o coeficiente de correlação dos pares epipolares gerados para cada MDS, além da realização de análise dos efeitos da inclinação do terreno sobre a qualidade altimétrica tomando como base o coeficiente de correlação. Os MDSs que apresentaram melhores resultados após emprego dos quatro testes foram utilizados para a ortorretificação da cena Nadir e as Ortoimagens resultantes foram avaliadas de maneira global empregando o PEC e de maneira local, onde verifIcou-se a influência da resolução radiométrica na vetorização da Ortoimagem. A última análise consistiu na realização de um refinamento nos valores de altitude dos MDSs que apresentaram melhor classificação, através do emprego da Fórmula de Koppe modificada por Kraus (2004), que leva em consideração a influência da declividade e do fator de Escala sobre as cenas quando tomadas de imagens aéreas. Esta Fórmula foi adaptada para uso em uma imagem orbital e utilizada no intuito de se obter um indicativo da localização do erro altimétrico sobre cada MDS, onde se gerou um novo modelo, denominado MDS Composto. Os resultados obtidos permitiram constatar que o sensor PRISM permite a obtenção de MDSs compatíveis as normas da Cartografia Nacional para a Escala de 1:25.000, havendo a necessidade de utilização de um número mínimo de sete pontos de controle associados a doze pontos de ligação e o uso das visadas Backward x Nadir (que apresentaram os melhores resultados) para a geração dos Modelos. O aumento do número de pontos controle para realização da correção geométrica empregando o Modelo de Toutin não trouxe melhorias significativas aos MDSs avaliados, embora os que apresentaram melhores resultados foram aqueles que utilizaram 60 pontos de controle em sua geração. A Metodologia proposta por IBGE (2009) se mostrou aplicável a regiões com características semelhantes à estudada neste trabalho, embora exista a necessidade de realização de testes em áreas com características semelhantes à estudada. O uso da Fórmula de Koppe modificada se mostrou satisfatório, permitindo associar em um único MDS os valores de altitude que apresentam o menor indicativo de erro encontrado para a componente altimétrica, sendo que os resultados obtidos através do emprego desta Equação foram superiores aos demais Modelos avaliados. As ortoimagens obtidas se enquadraram na Classe A do PEC para a escala de 1:25.000, contudo devido à baixa resolução radiométrica das cenas PRISM (8 bits) o processo de extração de elementos físicos, principalmente em áreas urbanas tornaram-se de difícil interpretação.

Darbe nagrinėjami nenusistovėjusio vandens tekėjimo reiškiniai, kurie atsiranda Kruonio HAE reversiniame kanale dėl netolygaus hidroagregatų veikimo juos paleidžiant ir stabdant. Tyrimų tikslas - nustatyti nenusistovėjusio tekėjimo dėsningumus Kruonio HAE reversiniame kanale ir jam artimiausioje Kauno marių dalyje. Tyrimų metodas – hidrodinamikos skaitmeninis modeliavimas MIKE21 aplinkoje. Hidrodinamikos modelyje panaudotas reversinio kanalo dugno skaitmeninis reljefo modelis, sudarytas stačiakampių gardelių tinklo (grido) pavidalu pagal naujausius batimetrinių matavimų rezultatus. Elementarių gardelių matmenys 5x5 m. Modelio pakraštinėms sąlygoms aprašyti pasirenkamos laiko funkcijos, kurios išreiškia kiekvieno HAE hidroagregato vandens debito kitimą laiko atžvilgiu įvairių modeliuojamų HAE darbo režimų scenarijuose. Kitoje modelio atviroje riboje nustatomas fiksuotas Kauno marių vandens lygis. Hidrodinamikos modeliavimo rezultatai išvedami ir užrašomi kiekvienu skaičiuojamojo laiko žingsniu, o jų analizė atliekama naudojant MIKE21 programų paketo įrankius. Hidrodinamikos modeliavimo rezultatų tikslumui ir patikimumui įvertinti buvo atlikta modelio patikra (t.y. verifikavimas), kurioje panaudoti realiai išmatuotų vandens lygių dinamikos ir tėkmės vektorių lauko krypčių vizualinių stebėjimų rezultatai. Analizuojant gautus modeliavimo rezultatus buvo nustatyti nenusistovėjusio vandens tekėjimo Kruonio HAE reversiniame kanale dėsningumai, kurie pasireiškia staigaus... [toliau žr. visą tekstą]
This work deals with fluctuations in the water flow regime that occur in the outlet channel of the Kruonis Pumped Storage Plant and are produced by uneven running of hydrounits while starting and stopping them. Research purpose: to determine the patterns of fluctuations in the water flow regime that occur in the outlet channel of the Kruonis Pumped Storage Plant and the nearest part of Kaunas Lagoon. Research method: numerical modeling of hydrodynamics in the MIKE21 environment. A digital terrain model of the reverse channel bottom consisting of a rectangular grid network (grid), made following the latest bathymetric measurements, was used for the hydrodynamic model. The elementary grid cell dimentions in the model were 5x5 m. To describe the boundary conditions of the model, time functions which express the water flow rate changes over time of each hydrounit in different operating modes of the KPSP were chosen. The fixed Kaunas Reservoir water level was set in the model as the other open boundary. The results of the hydrodynamic modeling were output and recorded at each computational time step and their analysis was performed using MIKE21 software package tools. To evaluate the accuracy and reliability of the hydrodynamic simulation results, a verification of the model was performed, which used the results of visual monitoring of actually measured water level dynamics and flow vector field directions . Analyzing the findings of simulation, consistent patterns of the... [to full text]

Geografinei informacijai apie erdvinį žemės paviršių kaupti pastaruoju metu vis dažniau naudojamas vietovės skenavimo lazeriu iš orlaivio metodas LIDAR (Light Detection and Ranging). Šiuo metodu gaunama nereguliari taškinė labai tanki trijų dimensijų žemės paviršiaus objektų išsidėstymą sumodeliuojanti geometrinė ir radiometrinė informacija. Tai gana neseniai atsiradęs būdas, naudojamas žemės topografijos duomenims užrašyti, kuris Lietuvoje dar tik pradedamas naudoti. Dėl to naudinga ištirti šio metodo patikimumą, palyginant su įprastais duomenų surinkimo metodais (GPS), ir įvertinti šio metodo panaudojimo galimybes. Darbe nagrinėjama nuotolinių tyrimų metodais (LIDAR) gautų duomenų patikimumo problema. Tyrimo tikslas – nustatyti įvairiais metodais gautų reljefo aukščių duomenų patikimumą, analizuojant Riešės upelio baseino reljefą. Tyrimo eigoje buvo surinkti įvairiais metodais gauti Riešės upelio baseino reljefo duomenys; atlikti natūriniai matavimai pasirinktuose kontroliniuose ploteliuose, naudojantis geodeziniais instrumentais; pagal nuotolinių tyrimų gautus rezultatus sudarytas skaitmeninis reljefo modelis ir įvertintas jų tikslumas. Darbe palyginus natūrinių matavimų ir nuotolinių tyrimų metodais gautus rezultatus įrodyta, jog nuotoliniais tyrimų metodais gauti duomenys yra patikimi ir juos galima naudoti baseino tūriui ir plotui skaičiuoti.
LIDAR terrain laser scanning technique is increasingly used in digital terrain model creation. This method provides dense uneven three-dimensional scatter geometric and radiometric information that simulates objects on earth’s surface. This is a relatively recent method used to record topographic data of the land. One of the key issues still associated with remote sensing methods is its reliability, which is why it is relevant to analyze and evaluate this aspect. This thesis aims at evaluating LIDAR data reliability, comparing them with data obtained by field measurements carried out at selected control areas using geodesic instruments. Riešės river basin area was selected as an object for the study and its elevation data have been investigated in the research. It was concluded that LIDAR data are reliable and can be used for the basin volume calculation. However, the size of the grid should be selected according to terrain relief.

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Due to particular interactivy mode performed by TV services, engines are requeried that allow to retrieve informations beyond those provided directly. In this sense, context-aware applications use relevant informations to provide support in tasks execution. To develop these kind of applications presents challenges in context capture from heterogeneous sources, as sensors; by representation more adjusted to perform context-aware behavior; and to enable infer knowledges. This dissertation proposes an approach for content personalization of Interactive TV Applications by context handling. To this end, a context modelling was achieved to describe the user information and sports content information semantic in an integrated way and services were developed whose features provides support to context usage.
Graças ao modo peculiar de interatividade realizada por aplicativos na TV, são necessários mecanismos que possibilitem recuperar informações além daquelas fornecidas diretamente. Neste sentido, aplicações sensíveis ao contexto utilizam informações consideradas relevantes para fornecer suporte à realização de tarefas. Desenvolver aplicações desta natureza apresenta desafios quanto a captura de dados a partir de diferentes fontes, tais como sensores; quanto a representação mais adequada para realizar comportamento sensível ao contexto; e capacitar a inferência de conhecimentos. Este trabalho propõe uma abordagem para personalização do conteúdo de aplicações de TV Digital Interativa através da manipulação de informações de contexto. Para tanto, foi realizada a especificação de um modelo contextual que descreve semântica de informações do usuário e de conteúdo esportivo de maneira integrada, e foram desenvolvidos serviços cujas funcionalidades oferecem suporte ao uso de contexto.

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PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares
O crescente avanço de novas tecnologias na área das geociências, como o posicionamento por GNSS, o mapeamento por GPR ou a geração de modelos tridimensionais com a técnica LIDAR permite a integração de técnicas de sensoriamento remoto em diferentes aplicações nas geociências. Para isso é necessário experimentar, testar e avaliar cientificamente o potencial de integração dessas diferentes tecnologias, de forma a explorar em sua plenitude os diferentes tipos de dados. A análise, descrição e interpretação de afloramentos são atividades corriqueiras dos trabalhos de campo geológicos. Apesar do avanço tecnológico das últimas décadas, a obtenção de dados quantitativos a partir do uso de instrumentos não se sobrepôs à tradicional forma de aquisição de dados pelos geólogos: a observação da rocha. Dessa forma, o estudo de afloramentos constitui uma fonte indispensável para a obtenção de dados intermediários entre as escalas megascópica (e.g., geologia regional) e microscópica (e.g., amostra), que por sua natureza são dependentes de aquisição por sensores remotos e instrumentos diversos. O principal desafio em pesquisas dessa natureza é integrar dados quantitativos e digitais, obtidos por instrumentos com diferentes princípios de aquisição e integrá-los aos dados qualitativos e analógicos obtidos pela subjetividade da percepção do geocientista. O objetivo deste trabalho foi analisar, testar e validar essa abordagem multidisciplinar para a modelagem de afloramentos considerando um estudo de caso real no Afloramento Morro Papaléo. Para tanto, considerou-se como premissa que o modelo geológico resultante da integração de dados de diferentes naturezas não tivesse erro posicional em ordem de grandeza superior à resolução espacial do sensor com maior limitação de amostragem. A integração de dados segundo procedimentos metodológicos adequados permitiu gerar um Modelo Digital de Afloramento (MDA) que tornou possível visualizar, medir e interpretar com exatidão a geologia a partir de uma representação geológica do objeto de estudo. A validação de campo foi realizada para assegurar que a qualidade da metodologia proposta pode ser utilizada nesse tipo de estudo. Quanto aos dados de subsuperfície, por meio de seções geofísicas, foi possível estabelecer correlações entre os dados obtidos com a técnica LIDAR, o que permitiu integrar dados de superfície e de subsuperfície. Portanto, com o estabelecimento do modelo 3D gerado numa base de dados consistente, calibrada e validada pode-se a qualquer tempo adicionar dados e incrementar o modelo de forma dinâmica.
The increasing advance of new technologies in the field of geosciences, such as GNSS positioning, mapping by GPR or the generation of three dimensional models with the LIDAR technique allows the integration of orbital and non-orbital remote sensing techniques for different applications in geosciences. Thus, it is necessary to experiment, test and scientifically evaluate the potential of integration of these different technologies in order to explore the different types of data. The analysis, description and interpretation of outcrops are daily activities of the geological fieldwork. Despite the technological advances in the last decades, the acquisiton of quantified data from instruments and sensors did not substitute the traditional source of data of the geologists: the observation of the rock. Thus, the study of outcrops is fundamental in the acquisition of intermediate data between the megascopic (e.g. regional geology) and microscopic scales (e.g., sample), quite dependent of acquisition by remote sensors and instruments. The main challenge in this type of research is to integrate quantitative digital data obtained by instruments and sensors based on different principles with qualitative, analogic data, obtained by the subjective perception of the geoscientist. The main purpose of this study was to analyze, test and validate this multidisciplinary approach to the modeling of outcrops considering a real case study in Morro Papaléo Outcrop. For this, it was considered as a premise that the geological model resulting from the integration of different data had not a positional error in an order of magnitude higher than the spatial resolution of the more limited sensor. The data integration using appropriate methodological procedures allowed generate a Digital Outcrop Model (DOM) which made it possible to view, measure and accurately interpret the geology from a 3D geological representation. The field validation was performed to ensure that the quality of the proposed methodology can be used in this type of study. Through geophysical sections was possible to correlate subsurface data with those obtained with the LIDAR technique, allowing data integration of surface and subsurface data. Therefore, with the establishment of the 3D model generated in a consistent database, calibrated and validated, at any time more data can be added to this dynamic model.

The growth of Web technologies has benefited researchers and the academic community by supporting the access of electronic publications as soon as they have been finished and published. In this context, Digital Libraries emerges as complex information systems which are essential for disseminating and preserving data, information and knowledge. However, due to the high amount of content available on the Web, specially in Digital Libraries, users face many correlated options, what result in the phenomenon known as information overload. Aiming to decrease or even eliminate these diffculties, recommender systems for Digital Libraries have been proposed and developed. This work presents a personalized recommender system which presents alternative ways to achieve better query results. For this, the main existing approaches of automatic recommendation have been studied in order to identify extension points and points to be improved. The proposed recommender system follows a hybrid approach which combines filtering techniques, content-based recommendation and collaborative recommendation. A hybrid recommendation engine has been proposed, which uses standard technologies for content description (Dublin Core), for communication with Digital Libraries (OAI-PMH Protocol ), as well as the user profile extracted from the curriculum vitae Lattes. The proposed solution has been evaluated in the context of the CiteSeer database, which contains papers and articles in the Dublin Core format. The preliminary results has showed an improvement in the quality of recommendation, thus presenting a better precision and coverage, when compared with existing approaches based either on content-based recommendation or on collaborative recommendation
O crescimento acelerado das tecnologias Web tem beneficiado pesquisadores e acadêmicos, pois as publicações de pesquisa podem ser acessadas eletronicamente tão logo elas tenham sido finalizadas e publicadas. Nesse contexto, surgem as Bibliotecas Digitais como um sistema de informação complexo que possui uma série de atividades que integram coleções, serviços e pessoas em suporte ao completo ciclo de criação, disseminação, acesso e preservação de dados, informação e conhecimento. No entanto, devido a enorme quantidade de conteúdo presente na Web, em particular nas Bibliotecas Digitais, usuários acabam se deparando com uma diversidade muito grande de opções, o que leva ao fenômeno conhecido como sobrecarga de informação. Com o objetivo de contribuir para amenizar ou até mesmo eliminar essas dificuldades, sistemas de recomendação para Bibliotecas Digitais têm sido propostos e desenvolvidos. Este trabalho segue essa direção, investigando soluções alternativas para alcançar mais qualidade nas indicações geradas por um sistema de recomendação na sua tarefa de ajudar os seus usuários. Para isso estudou-se as abordagens tratadas na literatura especializada sobre tais sistemas, propondo-se em seguida, um sistema de recomendação personalizada de artigos científicos para Bibliotecas Digitais. Tal sistema seguiu uma abordagem híbrida, procurando tirar proveito das características interessantes identificadas nas técnicas de filtragem e recomendação baseadas em conteúdo e colaborativa. Nesse sentido desenvolveu-se um engenho de recomendação híbrido que se utiliza de tecnologias padrão para a descrição de conteúdo (Padrão Dublin Core), comunicação com Bibliotecas Digitais (Protocolo OAI-PMH) e perfil do pesquisador (Currículo Lattes). Finalmente, avaliou-se o sistema proposto sobre uma base de dados do CiteSeer contendo artigos no formato Dublin Core, tendo os resultados preliminares mostrado-se satisfatórios melhorando a precisão na recomendação e a cobertura quando comparado com sistemas que implementam abordagens baseada em conteúdo e colaborativa isoladamente

Whereas manually drawn contours could contain artifacts related to hand tremor, automatically detected contours could contain noise and inaccuracies due to limitations or errors in the procedures for the detection and segmentation of the related regions. To improve the further step of description, modeling procedures are desired to eliminate the artifacts in a given contour, while preserving the important and significant details present in the contour. In this work, are presented a couple of polygonal modeling methods, first a method applied direct on the original contour and other derived from the turning angle function. Both methods use the following parametrization Smin e µmax to infer about removing or maintain a given segment. By the using of the mentioned parameters the proposed methods could be configured according to the application problem. Both methods have been shown eficient to reduce the influence of noise and artifacts while preserving relevant characteristic for further analysis. Systems to support the diagnosis by images (CAD) and retrieval of images by content (CBIR) use shape descriptor methods to make possible to infer about factors existing in a given contour or as base to classify groups with dierent patterns. Shape factors methods should represent a value that is aected by the shape of an object, thus it is possible to characterize the presence of a factor in the contour or identify similarity among contours. Shape factors should be invariant to rotation, translation or scale. In the present work there are proposed the following shape features: index of the presence of convex region (XRTAF ), index of the presence of concave regions (V RTAF ), index of convexity (CXTAF ), two measures of fractal dimension (DFTAF e DF1 TAF ) and the index of spiculation (ISTAF ). All derived from the smoothed turning angle function. The smoothed turning angle function represent the contour in terms of their concave and convex regions. The polygonal modeling and the shape descriptors methods were applied on the breast masses classification issue to evaluate their performance. The polygonal modeling procedure proposed in this work provided higher compression and better polygonal fitness. The best classification accuracies, on discriminating between benign masses and malignant tumors, obtain for XRTAF , V RTAF , CXTAF , DFTAF , DF1 TAF and ISTAF , in terms of area under the receiver operating characteristics curve, were 0:92, 0:92, 0:93, 0:93, 0:92 e 0:94, respectively.
Contornos obtidos manualmente podem conter ruídos e artefatos oriundos de tremores da mão bem como contornos obtidos automaticamente podem os conter dado a problemas na etapa de segmentação. Para melhorar os resultados da etapa de representação e descrição, são necessários métodos capazes de reduzir a influência dos ruídos e artefatos enquanto mantém características relevantes da forma. Métodos de aproximação poligonal têm como objetivo a remoção de ruídos e artefatos presentes nos contornos e a melhor representação da forma com o menor número possível de segmentos de retas. Nesta disserta ção são propostos dois métodos de aproximação poligonal, um aplicado diretamente no contorno e outro que é obtido a partir da função tangencial do contorno original. Ambos os métodos fazem uso dos parâmetros Smin e µmax para inferirem sobre a permanência ou remoção de um dado segmento. Com a utilização destes parâmetros os métodos podem ser configurados para serem utilizados em vários tipos de aplicações. Ambos os métodos mostram-se eficientes na remoção de ruídos e artefatos, enquanto que características relevantes para etapas de pós-processamento são mantidas. Sistemas de apoio ao diagnóstico por imagens e de recuperação de imagens por conte údo fazem uso de métodos descritores de forma para que seja possível inferir sobre características presentes em um dado contorno ou ainda como base para medir a dissimilaridade entre contornos. Métodos descritores de características são capazes de representar um contorno por um número, assim é possível estabelecer a presença de uma característica no contorno ou ainda identificar uma possível similaridade entre os contornos. Métodos para extração de características devem ser invariantes a rotação, translação e escala. Nesta dissertação são propostos os seguintes métodos descritores de características: índice de presença de regiões convexas (XRTAF ), índice da presença de regiões côncavas (V RTAF ), índice de convexidade (CXTAF ), duas medidas de dimensão fractal (DFTAF e DF1 TAF ) e o índice de espículos (ISTAF ). Todos aplicados sobre a função tangencial suavizada. A função tangencial suavizada representa o contorno em termos de suas regiões côncavas e regiões convexas. Os métodos de aproximação poligonal e descritores de características foram aplicados para o problema de classificação de lesões de mama. Os resultados obtidos, mostraram que os métodos de aproximação poligonal propostos neste trabalho resultam em polígonos mais compactos e com melhor representação do contorno original. Os melhores resultados de classificação, na discriminação entre lesões benignas e tumores malignos, obtidos por XRTAF , V RTAF , CXTAF , DFTAF , DF1 TAF e ISTAF , em termos da área sob a curva ROC, foram 0:92, 0:92, 0:93, 0:93, 0:92 e 0:94, respectivamente.
Mestre em Ciência da Computação

This research work concentrate on developing digital soil maps to support field based plant phenotyping research. We have developed soil organic matter content (OM), cation exchange capacity (CEC), natural soil drainage class, and tile drainage line maps using topographic indices and aerial imagery. Various prediction models (universal kriging, cubist, random forest, C5.0, artificial neural network, and multinomial logistic regression) were used to estimate the soil properties of interest.

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We propose a new dynamic simulation scheme for large-scale flood hazard modelling and prevention. The approach consists of a number of core parts: Digital terrain modelling with GIS data, Nona-tree space partitions (NTSP), Automatic River object recognition and registration, and a flood spreading model. The digital terrain modelling method allows the creation of a geometric real terrain model for augmented 3D environments with very large GIS data, and it can also use information gathered from aviation and satellite images with a ROAM algorithm. A spatial image segmentation scheme is described for river and flood identification and for a 3D terrain map of flooding region growth and visualisation. The region merging is then implemented by adopting Flood Region Spreading Algorithm (FRSA). Compared with the conventional methods, our approach has the advantages of being capable of realistically visualising the flooding in geometrically-real 3D environments, of handling dynamic flood behaviour in real-time and of dealing with very large-scale data modelling and visualisation.