Quality of orthophoto mosaics made with different methods
Keywords: aerial triangulation, digital elevation model (DEM), geometrical quality, GSD, orthophoto mosaic, UltraCam D
AbstractThe photogrammetric products, especially orthophotos, have become an important part of spatial databases, considering the modern technical development. The demand for more detailed photos and better resolutions is growing, which gives rise to the demand for photos with higher precision available as quickly as possible. Photogrammetric software used for producing ortophotos enables making some phases of orthophotos automatically. But every phase affects the quality of the final product. The question arises – How much can we use the automatic steps of the software for creating digital orthophotos if we want to keep the quality that is requested by users? For the answer of the before-mentioned question 4 orthophoto mosaics were made differing by their processing method, i. e. automated or manual processing. For that photographs made by a digital frame aerial camera UltraCam D were used as well as the photogrammetric software Photomod version 5.1 made in Russia. For the analysis the geometrical quality of each mosaic was investigated by ground control points measured in nature and on the mosaics. The accuracy is given by RMS not bigger than 0.45 meters. Three orthophoto mosaics were according to the given precision. The most geometrically accurate mosaic’s RMS was 0.308 m which is calculated in turn with the error 0.069 m in the manual project. Only the mosaic of the full-automatic project was not in the permitted size, the RMS was 1.805 m.
Environmental Engineering and Landscape Management