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Search Results: 1 - 6 of 6 matches for " Orthorectification "
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Orthorectification and Digital Elevation Model (DEM) Generation Using Cartosat-1 Satellite Stereo Pair in Himalayan Terrain  [PDF]
Vivek Kumar Singh, Prashant Kumar Champati Ray, Ayyeum Perumal Thillai Jeyaseelan
Journal of Geographic Information System (JGIS) , 2010, DOI: 10.4236/jgis.2010.22013
Abstract: High resolution data have high relief displacement in hilly terrains. Development of Digital Elevation model helps to assess bio resources more accurately in such terrains. While estimating bio resources in the Himalayan hilly terrain using multispectral LISS-III data of 23 m spatial resolution, the need for orthorectifcation of satellite data was necessary to correct for spatial distances due to high undulating slopes. Therefore, Cartosat stereo pair based Digital Elevation Model (DEM) was generated using the Rational Polynomial Coefficients (RPC) supplied along with the data products. By using the DEM orthorectification of LISS-III was created. In order to evaluate the positional accuracy of ortho rectified LISS-III Ground control points were selected using the Global Positioning System in differential GPS mode. As there is variation in the spatial distances and height over few points, the GCP corrected DEM was used for ortho rectifcation of Cartosat PAN and LISS-III data. This paper presents the procedure followed for ortho rectification and digital elevation model generation using Cartosat stereo pair data. The result of the study indicated high spatial resolution stereo images helped generation of three dimensional mountainous regions more accurately which helps in estimating the bio resources using multispectral LISS III data.
Avalia??o do potencial das imagens quickbird ortorretificadas para o mapeamento das propriedades localizadas na área de expans?o e vazios urbanos
Amorin, Amilton;Camargo, Paulo de Oliveira;Miyashita, Priscila Midori;
Boletim de Ciências Geodésicas , 2010, DOI: 10.1590/S1982-21702010000300006
Abstract: the images obtained by the sensor aboard the satellite quickbird provide the applications in many fields due to its high spatial resolution, spectral and temporal and inexpensive to purchase compared to conventional aerial photogrammetry. the supporting points, using the gps navigation along with the programs and async gar2rnx, make post-processing of the observable l1 carrier providing the three-dimensional positioning possible. this paper aims at analysing the positional accuracy provided by the orthorectified quickbird image, for use in pre-registration of properties located in the urban expansion area, as well as in empty urban and that are often not registered physically, affecting the urban realestate cadastre and specially damaging the local territorial planning and management. according to the obtained results, it was possible to map products useful to local governments (city hall) following the standard of cartographic accuracy, fitting into class a for the scale 1:10000, 1:5000 and 1:3000, and class b for the scale 1:2000, and with attractive costs compared to other methods of removal.
Pixel Discontinuity Repairing for Push-Broom Orthorectified Images  [PDF]
Jyun-Yi Lai, Ming-Fu Chen, Han-Chao Chang
Journal of Software Engineering and Applications (JSEA) , 2013, DOI: 10.4236/jsea.2013.64A004
Abstract:

Pixel discontinuity in orthoimages occurs frequently due to altitude variations in the pitch and heading of an airplane, and low performance of real-time analyzing software. This study proposes a scheme to resolve pixel discontinuity. The proposed scheme includes the following steps: 1) capture images by a self-made hyperspectral imager; 2) determine the pixel locations of orthoimages using a top-down approach; 3) repair discontinuities by the Nearest Neighbor (NN) or Bilinear Interpolation (BL) approaches; and, 4) perform a dynamic range adjustment on the orthoimages, according to the maximum pixel value of the raw images and orthoimages. After applying the proposed scheme, this study found that pixel discontinuity was eliminated by both approaches, and that the software dependability and image quality were improved substantially. In addition, the computational efficiency of the NN approach was roughly two minutes faster than that of the BL due to its simpler computation. However, BL produces smoother image edges for landscapes.

The Influence of DEM Quality on Mapping Accuracy of Coniferous- and Deciduous-Dominated Forest Using TerraSAR?X Images
Sonia M. Ortiz,Johannes Breidenbach,Ralf Knuth,Gerald K?ndler
Remote Sensing , 2012, DOI: 10.3390/rs4030661
Abstract: Climate change is a factor that largely contributes to the increase of forest areas affected by natural damages. Therefore, the development of methodologies for forest monitoring and rapid assessment of affected areas is required. Space-borne synthetic aperture radar (SAR) imagery with high resolution is now available for large-scale forest mapping and forest monitoring applications. However, a correct interpretation of SAR images requires an adequate preprocessing of the data consisting of orthorectification and radiometric calibration. The resolution and quality of the digital elevation model (DEM) used as reference is crucial for this purpose. Therefore, the primary aim of this study was to analyze the influence of the DEM quality used in the preprocessing of the SAR data on the mapping accuracy of forest types. In order to examine TerraSAR-X images to map forest dominated by deciduous and coniferous trees, High Resolution SpotLight images were acquired for two study sites in southern Germany. The SAR images were preprocessed with a Shuttle Radar Topography Mission (SRTM) DEM (resolution approximately 90?m), an airborne laser scanning (ALS) digital terrain model (DTM) (5?m resolution), and an ALS digital surface model (DSM) (5?m resolution). The orthorectification of the SAR images using high resolution ALS DEMs was found to be important for the reduction of errors in pixel location and to increase the classification accuracy of forest types. SAR images preprocessed with ALS DTMs resulted in the highest classification accuracies, with kappa coefficients of 0.49 and 0.41, respectively. SAR images preprocessed with ALS DTMs resulted in greater accuracy than those preprocessed with ALS DSMs in most cases. The classification accuracy of forest types using SAR images preprocessed with the SRTM DEM was fair, with kappa coefficients of 0.23 and 0.32, respectively.Analysis of the radar backscatter indicated that sample plots dominated by coniferous trees tended to have lower scattering coefficients than plots dominated by deciduous trees. Leaf-off images were only slightly better suited for the classification than leaf-on images. The combination of leaf-off and leaf-on improved the classification accuracy considerably since the backscatter changed between seasons, especially in deciduous-dominated forest.
Generation of orthorectified range images for robots using monocular vision and laser stripes
Orlandi,J. G. N.; Amaral,P. F. S.;
Latin American applied research , 2008,
Abstract: range images have a key role for surface mapping in robot navigation and control. the robot control system can easily identify objects and obstacles by manipulating range images, however most of these range images are acquired in perspective projection, thus object position may be incorrect due to distortion caused by the perspective effect. this paper proposes an easy and efficient way to acquire range images, with a single ccd camera in conjunction with laser stripes and afterwards these range images are orthorectified to turn out to surface maps. these orthorectified range images are very useful for biped and quadruped robots, orientating them when navigating among obstacles while robot manipulators can use them to find objects by setting up their joints and picking tools.
Generation of orthorectified range images for robots using monocular vision and laser stripes
J. G. N. Orlandi,P. F. S. Amaral
Latin American applied research , 2008,
Abstract: Range images have a key role for surface mapping in robot navigation and control. The robot control system can easily identify objects and obstacles by manipulating range images, however most of these range images are acquired in perspective projection, thus object position may be incorrect due to distortion caused by the perspective effect. This paper proposes an easy and efficient way to acquire range images, with a single CCD camera in conjunction with laser stripes and afterwards these range images are orthorectified to turn out to surface maps. These orthorectified range images are very useful for biped and quadruped robots, orientating them when navigating among obstacles while robot manipulators can use them to find objects by setting up their joints and picking tools.
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