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 Himala...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.展开更多
An increasing number of low,medium,and high resolution SAR satellites creates a demand for a generalized sensor model to replace the rigorous sensor model(RSM).The rational polynomial coefficient(RPC)model is a generi...An increasing number of low,medium,and high resolution SAR satellites creates a demand for a generalized sensor model to replace the rigorous sensor model(RSM).The rational polynomial coefficient(RPC)model is a generic sensor model which accurately fits the object-image geometry for various sensor systems with different coefficient values.It has been widely used as an alternative to RSM for photogrammetric processing of optical images,but its applications to SAR images are rarely discussed in publications.In this paper,the feasibility and practicability of the RPC model for SAR images are studied.The RPC model can not only be used to replace the RSM(range–Doppler model for SAR),but also applied to the processing chain for SAR data,thus facilitating the processing of SAR and InSAR data for end users.展开更多
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 pix...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.展开更多
文摘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.
基金Supported by National Technology Support Project(Nos.2011BAB01B01,2012BAH28B04)the National Natural Science Foundation of China(No.40930532)the National High Technology Research&Development Programme of China(No.2011AA120404).
文摘An increasing number of low,medium,and high resolution SAR satellites creates a demand for a generalized sensor model to replace the rigorous sensor model(RSM).The rational polynomial coefficient(RPC)model is a generic sensor model which accurately fits the object-image geometry for various sensor systems with different coefficient values.It has been widely used as an alternative to RSM for photogrammetric processing of optical images,but its applications to SAR images are rarely discussed in publications.In this paper,the feasibility and practicability of the RPC model for SAR images are studied.The RPC model can not only be used to replace the RSM(range–Doppler model for SAR),but also applied to the processing chain for SAR data,thus facilitating the processing of SAR and InSAR data for end users.
文摘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.
