Edson Aparecido Mitishita

Image georeferencing using LIDAR data

LIDAR technology is increasingly becoming an industry-standard tool for collecting high resolution data about physical surfaces. LIDAR is characterized by directly collecting numerical 3D coordinates of object space points. Still, the discrete and positional nature of LIDAR datasets makes it difficult to derive semantic surface information. Furthermore, reconstructed surfaces from LIDAR data lack any inherent redundancy that can be utilized to enhance the accuracy of acquired data. In comparison to LIDAR systems, photogrammetry produces surfaces rich in semantic information that can be easily identified in the captured imagery. The redundancy associated with photogrammetric intersection results in highly accurate surfaces. However, the extended amount of time needed by the photogrammetric procedure to manually identify conjugate points in overlapping images is a major disadvantage. The automation of the matching problem is still an unreliable task especially when dealing with large scale imagery over urban areas. Also, photogrammetric surface reconstruction demands adequate control in the form of control points and/or GPS/INS units. In view of the complementary characteristics of LIDAR and photogrammetric systems, a more complete surface description can be achieved through the integration of both datasets. The advantages of both systems can be fully utilized only after successful registration of the photogrammetric and LIDAR data relative to a common reference frame. The adopted registration methodology has to define a set of basic components, mainly: registration primitives, mathematical function, and similarity assessment. This paper presents the description and implementation of a registration approach that utilizes straightline features derived from both datasets as the registration primitives. LIDAR lines are used as control for the imagery and are directly incorporated in the photogrammetric triangulation. The performance analysis is based on the quality of fit between the LIDAR and photogrammetric models including derived orthophotos.

New Models for Scattering Bias Compensation in Time-of-Flight Range Camera Self-Calibration

AbstractThe geometric calibration of time-of-flight range cameras is a necessary quality assurance measure performed to estimate the interior orientation parameters. Self-calibration from a network of range imagery of an array of signalized targets arranged in one or two planes can be used for this purpose. The latter configuration requires the addition of a parametric model for internal light scattering biases in the range observations to the background plane due to the presence of the foreground plane. In a previous study of MESA Imaging SwissRanger range cameras, such a model was developed and shown to be effective. A new parametric model is proposed here because the scattering error behavior is camera model dependent. The new model was tested on two pmdtechnologies range cameras, the CamCube 3.0 and CamBoard nano, and its effectiveness was demonstrated both graphically and statistically. The improvement gained in the root-mean square of the self-calibration range residuals of 22 and 32%, respectively,...

Two Methods to Estimate the Spot Size of Terrestrial Laser Scanners

This technical note presents the results of a study focused on the evaluation of laser beam divergence and its effect on the spot size of terrestrial laser scanners. For this purpose, experiments were accomplished using the Leica HDS3000 and HDS6000 laser scanners. Two methods for the evaluation of the spot size are compared: a direct method, based on the analysis of the capacity of the laser beam to go through small slots, and an analytical method that estimates the spot diameter based on the edge effect. Based on the performed experiments, the development of a conceptual model of the edge effect at sharp edges is described for each method and validated. The experiments proved that the methods are suitable to analyze the variation of the diameter of the spot as a function of the distance. The estimate of the spot size using slots of varying sizes is a direct and easy to use method, but the computation of the spot size using the sharp edge model is more stable in relation to the point density, and can be ...

A study of integration of LIDAR and photogrammetric data sets by indirect georeferencing and in situ camera calibration

ABSTRACT This article aims to study the importance of in situ camera calibration for the integration of light detection and ranging (LIDAR) and photogrammetric data sets by indirect georeferencing. For this purpose, the in situ camera calibration was performed to estimate the interior orientation parameters (IOP) in the flight condition, using a sub-block of images (six images from two opposite flight strips), extracted from the entire block and a set of LIDAR control points (LCPs) computed by three planes intersection, extracted from the LIDAR point cloud on the building roofs. In order to evaluate the accuracies of the LIDAR and photogrammetric integration, two experiments were performed: the first used IOP from terrestrial calibration, and the second employed the IOP from the in situ calibration. The analysis of the obtained results from the performed experiments showed that the horizontal and vertical accuracies, computed by checkpoints discrepancies, are improved significantly when the IOP from in situ calibration are used. For this condition, the values of horizontal and vertical RMSEs of discrepancies are close to 0.40 and to 0.50 m, respectively.

A Study on In Situ Calibration of an Off-The-Shelf Digital Camera Integrated to a Lidar System

Photogrammetric procedures using the integration of imagery and light detection and ranging (Lidar) datasets are becoming common in mapping companies nowadays. When photogrammetric and Lidar surveys are performed simultaneously while having the camera connected to the Lidar system, the images exterior orientation parameters computed from the Lidar system can be used to perform photogrammetric applications. To implement such approach, camera calibration procedures should be applied to obtain accurate interior orientation parameters. This paper shows the performed study and experimental results from an in situ self-calibration using simultaneously collected imagery and Lidar datasets. The experimental study is conducted to devise a methodology for the in situ self-calibration that uses a set of vertical control points, extracted from Lidar point cloud, as well as the three-dimensional coordinates of the camera exposure stations, computed from the Lidar trajectory. For the small photogrammetric block used in this study, the results from the performed experiments demonstrated that the in situ self-calibration is required to obtain horizontal accuracies of approximately one image pixel on the ground in bundle adjustment assisted by direct measured of the coordinates of the camera exposure stations.

A influência da calibração aérea de uma câmara digital de baixo custo integrada com um sistema LIDAR no processamento de aerotriangulação

Esta pesquisa teve como objetivo investigar a influencia da calibracao aerea de uma câmara digital de baixo custo, integrada fisicamente com um sistema LIDAR, na correcao dos erros sistematicos de observacoes fotogrametricas para o processo de aerotriangulacao. A calibracao aerea foi realizada com fotografias tomadas de um campo de prova empregando-se duas configuracoes de bloco fotogrametrico: sem faixas cruzadas e faixas cruzadas. As coordenadas das estacoes de exposicao, provenientes da integracao da câmara com os sensores de orientacao e posicao do sistema LIDAR, foram utilizadas como injuncao nos processamentos de calibracao aerea. A verificacao do desempenho dos parâmetros de orientacao interior (POI), determinados nas calibracoes aereas, foi realizada atraves de processamentos de aerotriangulacao de um bloco fotogrametrico (utilizando as coordenadas das estacoes de exposicao), obtido em local e epoca diferente do que foi empregado nos procedimentos de calibracao aerea. Parâmetros de orientacao interior determinados pelo Metodo das Câmaras Convergentes, utilizando um campo de prova terrestre, tambem foram utilizados para a correcao de erros sistematicos das observacoes fotogrametricas deste bloco de fotografias simplesmente para fins de comparacoes. Os resultados demonstraram que as exatidoes obtidas nos processamentos de aerotriangulacao empregando os POI provenientes das calibracoes aereas foram consideravelmente superiores as exatidoes obtidas no processamento empregando os POI determinados na calibracao terrestre, principalmente no que se refere a exatidao altimetrica. Conclui-se que a exatidao altimetrica dos processamentos utilizando injuncao nas coordenadas do centro perspectivo da câmara apresenta-se mais dependente da qualidade dos POI empregados do que a exatidao planimetrica.

ORIENTAÇÃO EXTERIOR DE UM PAR ESTEREOSCÓPICO IKONOS II COM BASE NO MODELO NÃO-RIGOROSO DLT

O crescente avanco tecnologico ocorrido nos ultimos anos, tanto da area da Informatica, Fotogrametria e tambem Sensoriamento Remoto, vem contribuindo significativamente para diversas pesquisas sobre extracao de informacoes tridimensionais a partir de imagens de alta resolucao. No presente trabalho, uma solucao utilizando modelagem nao rigorosa baseada na transformacao matematica DLT (Direct Linear Transformation) foi utilizada para a orientacao exterior de um par estereoscopico de imagens Ikonos II e determinacao de coordenadas tridimensionais por interseccao fotogrametrica. O objetivo principal foi o de avaliar o desempenho do modelo na aplicacao, como tambem a obtencao de melhor configuracao de pontos de apoio necessarios na orientacao exterior para fins da determinacao de coordenadas tridimensionais por intersecao espacial. Os experimentos realizados permitiram recomendar a configuracao adequada para a distribuicao dos pontos de apoio, onde a exatidao planimetrica foi equivalente a precisao teorica toleravel igual a um pixel de erro nas observacoes, enquanto a exatidao altimetrica ficou proxima de 1,5 pixels.

The Influence of Sub-Block Position on Performing Integrated Sensor Orientation Using In Situ Camera Calibration and Lidar Control Points

The accuracy of photogrammetric and Lidar dataset integration is dependent on the quality of a group of parameters that models accurately the conditions of the system at the moment of the survey. In this sense, this paper aims to study the effect of the sub-block position in the entire image block to estimate the interior orientation parameters (IOP) in flight conditions to be used in integrated sensor orientation (ISO). For this purpose, five sub-blocks were extracted in different regions of the entire block. Then, in situ camera calibrations were performed using sub-blocks and sets of Lidar control points (LCPs), computed by a three planes’ intersection extracted from the Lidar point cloud on building roofs. The ISO experiments were performed using IOPs from in situ calibrations, the entire image block, and the exterior orientation parameters (EOP) from the direct sensor orientation (DSO). Analysis of the results obtained from the ISO experiments performed show that the IOP from the sub-block positioned at the center of the entire image block can be recommended.

Assessing snow extent variations of Illimani mountain with Landsat NDSI

Snow in the mountains is important because it keeps freshwater resources and supplies water for agriculture and human consumption. One of the most well-known mountains in Bolivia is the Illimani. In this paper the results of a multitemporal analysis of the snow cover at the Illimani are shown. Therefore, Landsat imagery of two years, 2010, and 1016 is presented. Snow cover is estimated from Landsat imagery using image processing and a snow-index. The temporal variation along a year is also compared to historical records. The results showed the seasonal variation of the snow cover area and that the glacier area is reducing.

Accuracy Improvements in the Orientation of ALOS PRISM Images Using IOP Estimation and UCL Kepler Platform Model

This paper presents a study that was conducted to determine the orientation of ALOS (Advanced Land Observing Satellite) PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping) triplet images, considering the estimation of interior orientation parameters (IOP) of the cameras and using the collinearity equations with the UCL (University College of London) Kepler platform model, which was adapted to use coordinates referenced to the Terrestrial Reference System ITRF97. The results of the experiments showed that the accuracies of 3D coordinates calculated using 3D photogrammetric intersection increased when the IOP were also estimated. The vertical accuracy was significantly better than the horizontal accuracy. The usability of the estimated IOP was tested to perform the bundle block adjustments of another neighbouring PRISM image triplet. The results in terms of 3D photogrammetric intersection were satisfactory and were close to those obtained in the IOP estimation experiment.