MOSAICO COM IMAGENS DIGITAIS

Este trabalho apresenta o desenvolvimento de um sistema para montar um mosaico, concatenando imagens provenientes de câmaras digitais. Foram implementados e testados três métodos para concatenação de imagens. O primeiro denominado de método direto, utiliza a transformação geométrica afim na forma inversa para a junção das imagens. O segundo denominado de método indireto, utiliza a transformação afim direta. E o terceiro método, indireto com correção radiométrica, utiliza a transformação afim direta com correção radiométrica na área de transição (superposição), baseada na média ponderada das cores das duas imagens adjacentes. Através de testes realizados concluiu-se que o método indireto para a concatenação de imagens digitais, utilizando a transformação afim direta, com ajuste radiométrico, mostrou-se mais adequado para a solução do problema. Digital image mosaic Abstract This work presents the development of a system to mount a mosaic, concatenating images proceeding from digital cameras. Three different methods were implemented and tested for concatenating of images. The first one called of "direct method", uses the affine geometric transformation in the inverse form. The second method called "indirect method", it uses the affine geometric transformation at the direct way to join images. The third method called indirect with radiometric correction uses the direct affine transformation with radiometric correction in the transition area (overlapping), based in the weighed mean of the intensity of the two adjacent images. The tests showed that the indirect method using the affine geometric transformation with radiometric adjustment is more appropriate to the problem solution

Monoscopic method for the automatic determination of height of buildings in air photos

This paper proposes a monoscopic method for automatic determination ofbuilding’s heights in digital photographs areas, based on radial displacement ofpoints in the plan image and geometry at the time the photo is obtained.Determination of the buildings’ heights can be used to model the surface in urbanareas, urban planning and management, among others. The proposed methodologyemploys a set of steps to detect arranged radially from the system ofphotogrammetric coordinates, which characterizes the lateral edges of buildingspresent in the photo. In a first stage is performed the reduction of the searching areathrough detection of shadows projected by buildings, generating sub-images of theareas around each of the detected shadow. Then, for each sub-image, the edges areautomatically extracted, and tests of consistency are applied for it in order to becharacterized as segments of straight arranged radially. Next, with the lateral edgesselected and the knowledge of the flight height, the buildings’ heights can becalculated. The experimental results obtained with real images showed that theproposed approach is suitable to perform the automatic identification of thebuildings height in digital images.Este trabalho propõe um método monoscópico para a determinação automática daaltura de edifícios em fotografias aéreas digitais, baseada no deslocamento radialdos pontos projetados no plano-imagem e na geometria no momento da obtenção dafotografia. A determinação da altura de edifícios pode ser utilizada para amodelagem da superfície em áreas urbanas, planejamento e gerenciamento urbano,entre outros. A metodologia proposta emprega um conjunto de etapas para adetecção de bordas dispostas radialmente em relação ao sistema de coordenadasfotogramétrico, sendo que estas bordas caracterizam as arestas laterais verticais dosedifícios presentes numa fotografia. Na primeira etapa realiza-se a redução doespaço de busca por meio da detecção das sombras projetadas pelos edifícios,gerando sub-imagens das áreas no entorno de cada sombra detectada. Em seguida,para cada sub-imagem são extraídas automaticamente bordas que passam por testesde consistência de modo que sejam caracterizados como segmentos de retadispostos radialmente. Deste modo, a partir destas arestas, e com o conhecimento daaltura de vôo, são estimadas as alturas dos edifícios. Os resultados alcançados emexperimentos com imagens reais digitalizadas, obtidas com câmaras métricas,mostraram-se promissores para a determinação das alturas de edifícios

Visualização 3D de uma imagem digital: metodologia e potencial cartográfico

This article presents a methodology for 3D visualization of a digital image and discusses its cartographic potential. Assuming that a regular DTM (Digital Terrain Model) is available, whose points are connected to form a triangular mesh, a shading methodology is applied triangle-by-triangle. This requires the computation of gray levels of image points corresponding to the pixels of 3D visualization plane, what in turn requires the modeling of the sensor used to acquire the image. Next, a shading model may be used to add artificially an extra effect of shading to the gray levels previously obtained, generating, e.g., shadows along the most elevated slopes opposed to the artificial light source. Finally, a projection model is used to obtain the 3D perception on the visualization plane. Results obtained were sufficient, showing that the 3D visualization methodology has the potential to be used in several cartographic application, as, e.g., in the cartographic revision

Desenvolvimento de um Sistema de Orientação e Restituição de Estereoimagens Orbitais

This paper aims to present one system of orientation and restitution the digital images using stereoscopic resources. The orientation of the pair of images was performed with the models of transformation DLT (Direct Linear Transformation), APM (Afine Projection Mode), 2 nd order polynomial and rational equations of 1st order. To validate the developed system was performed ALOS/PRISM-1B imaging experiments, the results showed that the system was successfully developed.Pages: 2383-239

RADAR FOTOGRAMÉTRICO: CÁLCULO DA VELOCIDADE DE UM OBJETO A PARTIR DE UMA SEQÜÊNCIA DE IMAGENS DIGITAIS

The aim of this paper is the determination of the velocity of an object in movement, from a sequence of images, obtained by a digital video camera Sony DRS-200A. The velocity calculation is accomplished in two stages. In the first, techniques of Digital Processing of Images are applied, to determine automatically the photo-coordinates of the vehicle in the times t1 and t2 (known). In the second stage, the modified collinearity equations are applied the vector velocity is added, in order to calculate the coordinates (the object space) and the constant velocity of the vehicle. The experiments were carried out by using images obtained from a scene (scale model) that simulated a vehicle in movement. This methodology was applied in the images for the determination of the velocity, whose results show the potential of the technique in metric applications that use video camera

Análise comparativa entre modelos rigorosos e empíricos na orientação de imagens orbitais

Nowadays, orbital images can be considered the main source of spatial information providing support in several applications such as urban planning, topographic mapping, deforestation management, and so on. However, the quality of the orbital images georeferenced using ephemerides and attitude data is not sufficient in applications that require high metric accuracy. As a consequence, it is necessary to correct these images using ground control points through rigorous or empirical mathematical models. The aim of this work is to compare the results obtained with rigorous and empirical models in the orientation process, which is accomplished before the image geometric correction step. The collinearity model adapted to the pushbroom geometry was used as a rigorous model. The empirical models considered were: the Rational function model, the affine transformation, the polynomial model and the DLT (Direct Linear Transformation) model. The results showed that the rigorous model provided better results when compared to those obtained with the empirical models in the orientation process of ALOS/PRISM images.Pages: 2360-236

Visualização 3D de uma imagem digital: metodologia e potencial cartográfico

This article presents a methodology for 3D visualization of a digital image and discusses its cartographic potential. Assuming that a regular DTM (Digital Terrain Model) is available, whose points are connected to form a triangular mesh, a shading methodology is applied triangle-by-triangle. This requires the computation of gray levels of image points corresponding to the pixels of 3D visualization plane, what in turn requires the modeling of the sensor used to acquire the image. Next, a shading model may be used to add artificially an extra effect of shading to the gray levels previously obtained, generating, e.g., shadows along the most elevated slopes opposed to the artificial light source. Finally, a projection model is used to obtain the 3D perception on the visualization plane. Results obtained were sufficient, showing that the 3D visualization methodology has the potential to be used in several cartographic application, as, e.g., in the cartographic revision

Mensuração da velocidade de deslocamento de corpos rígidos em tempo real por análise de sequência de imagens e pela transformação empírica baseada nas funções racionais

Este trabalho apresenta uma metodologia voltada para mensurar a velocidade de um corpo rígido em movimento, tendo como ponto de partida, uma sequência de imagens obtidas por meio de uma filmadora digital. No processo de mensuração da velocidade, na etapa de identificação dos corpos em movimento, é utilizada uma técnica de segmentação baseada na média temporal dos valores de cada pixel registrados em N quadros de imagens consecutivos, em que, após a identificação desses corpos, é realizada a transformação dos pontos no plano imagem para o espaço objeto, por meio do modelo matemático definido como funções racionais. Conhecendo-se as coordenadas dos pontos no espaço objeto, a velocidade de deslocamento do corpo pode ser calculada, através do intervalo de tempo obtido pela quantidade de quadros que a câmara captura por segundo. Para validar a metodologia proposta foi realizado um experimento que contou com a utilização de um aparelho denominado trilho de ar, cinco sensores fotoelétricos dispersos sobre o mesmo com distancias conhecidas entre si e um cronômetro ligado aos sensores. No momento em que um corpo em movimento passa por um sensor, o cronômetro é paralisado e com isso, se tem a distância percorrida pelo corpo entre cada sensor e, quanto tempo foi necessário para percorrer cada uma dessas distâncias. Com esses dados em mãos é realizada uma comparação dos resultados obtidos por meio da análise de sequência de imagens com os resultados obtidos através dos cronômetros e dos sensores fotoelétricos

Mapeamento fotogramétrico da cobertura do solo do Alto da Bacia Hidrográfica do rio Santo Anastácio – 1978 e 2008

This paper aims to present the map design and production of temporal maps of the Alto da Bacia Hidrográfica do Rio Santo Anastácio, located in Presidente Prudente municipality, São Paulo State, based on aerial images from two years: 1978 and 2008. The mapping was done by photogrammetric method in the LPS Leica Photogrammetric Suite. The land cover thematic maps were produced in the Arcgis 9.3. These maps were used to compare the land cover change along 30 years. A quantitative analysis was performed in the GIS environment.Pages: 2391-239

A influência da configuração de pontos de apoio na triangulação de imagens PRISM/ALOS

The aim of this work is to analyze the results of bundle block adjustment using images of the PRISM/ALOS sensor, with processing level 1B1, for different configurations of ground control points (GCP). This analysis was performed for a set of 6 triplets simultaneously processed. In all trials the processing was performed without the use of rational polynomial coefficients (RPCs). Firstly, the results with 3 groups of exterior orientation parameters (EOP), considering different orders for the polynomials were analyzed. These polynomials are used in the collinearity equation and all this processing was performed in LPS - Leica Photogrammetric Suite. Then, the results with different GCP number and configurations were analyzed. After selecting the group of polynomial to model the satellite orbit and also to choose the GCP configuration, i.e, with RMSE less than 1 GSD (Ground Sample Distance) and fewer number of ground control points per image, the generation and editing of DTM of the region was made. Following, a topographic map at 1;25.000 scale of the regions was generated. After the quality control of this product, based on 20 independent check points, the obtained product was classified as class A in planimetry and B in altimetry, according to the Brazilian accuracy standards (Brazil, 1984).Pages: 2105-211