QUALITY ASPECTS OF TRUE ORTHOPHOTO IN URBAN AREAS

Abstract. Orthophotos are one of the most popular photogrammetric products and have been a leading source of up-to-date 2D data of urban areas for years. In the last few years, together with innovations in the area of Dense Image Matching, Digital Surface Models created with dense image matching start to be utilized as the height source during orthorectification. Recently this production workflow of true orthophotos were adopted to production standard in many countries. The aim of the presented research was to evaluate recent developments in the area of automatic true orthophoto generation for urban areas and to define factors which have the main influence on the quality of the final product. Obtained results showed that besides of the image overlap, the main factors which have direct influence on the resulted true orthophoto are the occurrence of shadows and vegetation (trees). One of the outcomes of the presented research was that the quantitative methods develop for quality evaluation of Digital Surface Models and Point Clouds are not directly transferable on the quality evaluation of true orthophotos.