| Abstract |
True orthoimage generation has become one of the most investigated research topics motivated by the growing technology of high-resolution image acquisition. Unfortunately, problems for orthoimage generation originate from the non correspondence between the information sampled in the image with these represented in the Digital Surface Model (DSM). If there are features represented in the image but do not exist in the DSM, they would not be rectified correctly. On the other hand, if there is information about the surface recorded in the DSM and hidden in the image by an object’s relief the double mapping effect would appear in the areas obscured by the object. Thus, a complete representation of the surface in the form of dense DSM is implemented. This introduces semi-global matching (SGM) algorithm for pixelwise matching and dense DSM generation. In this research, an automated procedure for true-orthoimage generation from high resolution aerial imagery is presented. The procedure compromises three main steps: (i) Aerial triangulation with bundle block adjustment, (ii) DSM generation using SGM technique, and (iii) true orthoimage generation by back projecting the dense DSM generated from the second step. The use of SGM for DSM generation has developed promising results for orthoimage generation. Using an accurate DSM generated from the image itself refined from occlusions and outliers eliminates the appearance of the lean and the serious ghost effect with no need for subsequent steps for occlusion detection and elimination. |
