Occlusion‐Compensated True Orthorectification For High‐Resolution Satellite Images

Abstract

This paper describes a method to generate true ortho-images from highresolution satellite images. Multi-view images are used to compensate for hidden areas. This work includes three steps: (1) the generation of traditional ortho-images using a terrain model, (2) the relief correction for buildings, and (3) the detection of, and compensation for, hidden areas. A rational function model (RFM) is used to determine the geometric correspondence between the image space and the object space. In the generation of traditional ortho-images, RFM parameters and a digital terrain model (DTM) are employed to rectify tilt displacements and relief displacements for the terrain. Then, using a digital building model (DBM), relief displacements for buildings are computed. The purpose of the detection of hidden areas is to avoid double mapping. Considering the satellite's small field of view, an efficient method for the detection of hidden areas and building rectification is proposed. The test area covers the city of Hsinchu in northern Taiwan. The test images are obtained from the QuickBird satellite.

True Ortho Generation of Urban Area Using High Resolution Aerial Photos

“…Among multiple object points along the same line of sight competing for a single image pixel, the point closest to the perspective centre has the minimum distance value and is judged to be visible, while the other further points are considered invisible. Some modified variants of z-buffer have been proposed to conquer its drawbacks or to extend to rectify images taken by pushbroom sensors (Amhar et al, 1998;Rau et al, 2000;Nielsen, 2004;Oda et al, 2004;Bang et al, 2007;Habib et al, 2007;Chen et al, 2007;Antequera et., 2008;Bang and Kim, 2010).…”

“…Binary tree ray tracing (Nielsen, 2004) 3D TIN Extra storage for indexing Triangle sorting (Oda et al, 2004;Karras et al, 2007;Barazzetti et al, 2014) Hybrid 2D/3D TINs Prone to sorting errors Polygon (Kuzmin et al, 2004;Chen et al, 2007) Resolution independent, less memory False visible polygons Table 1. Visibility analysis methods However, these approaches require using different algorithms to locate the perspective centres and/or nadir points for different imaging sensors, and also assume that the imaging ray from the ground surface to the sensor is a straight line.…”

“…Xin (2011) used graph cuts to minimize a pixel based energy cost with geometry, smoothness and visibility terms. The intersection testing based approaches are binary tree based ray tracing (Nielsen, 2004), triangle based visibility sorting (Oda et al, 2004;Karras et al, 2007;Barazzetti et al 2014), and polygon based solutions (Kuzmin et al 2004;Chen et al 2007). In Wang and Xie (2012), the corners of polygons describing roofs and walls are projected to a horizontal plane along the perspective direction by an iteration procedure, and the occluded region is decided by calculating the intersection points of projecting lines and the entire DSM.…”

A New Image Processing Procedure Integrating PCI-RPC and ArcGIS-Spline Tools to Improve the Orthorectification Accuracy of High-Resolution Satellite Imagery

“…Furthermore, both polynomials are the functions of ground coordinates. Therefore, the RPC model is for further generalization for polynomial model and linear transform model and it is suitable for different types of sensors [8,12]. In the RPC rectification model, the image coordinates are the ratio of two polynomials in which the three-dimensional coordinates of GCPs are set as independent variables as follows in Equation (2) [2,15,20,25,27,29,30]:…”

“…Therefore, the spline function is established for these points respectively to calculate the correct value and obtain local geometric corrected coordinates point-by-point, so as to improve the accuracy of image orthorectification [19]. Essentially, local geometric correction is used to transform physical coordinates to user coordinates so that the spatial information of ArcGIS database has a practical significance [2,25]. Finally, based on the tested results, the proposed procedure was evaluated and relevant issues were discussed.…”