Investigation of Accuracy for Digital Elevation Models Generated with Different Methods in Photogrammetry

This paper describes the methodology of a DEM generation from stereo aerial images and the results of experiments in terms of accuracy of generated DEM. In this study, Images, which have 1/10000 and 1/16000 scale, and a test area established about 1 km in Selcuk University Campus Area were used. Aerial photographs were scanned by ZEISS SCAI Photogrammetric Scanner (pixel size is 21μ). Aerial images, which have 1/10000 scale, were restitutied by Zeiss Planicomp P3 Analytical Instrument. The DEM, which belong to test area, were produced by progressive, selective and composite sampling methods. We have developed a new software on PC’s that can automatically generate DEM from stereo aerial images for restitution of images 1/16000 scale. In this software, pixel and image coordinates of points in left and right image are calculated by using colinearity equations. Left and right windows are matched and this process is repeated in various ±∆Z range. Elevation values obtained from the best-fixed matching are automatically selected as optimum elevation value. Elevation values of points in the test area are calculated by bilinear interpolation method which uses coordinates of above points (X,Y,Z). Moreover, Elevations of points in test area are manually produced from PHOTOMOD software. RMS obtained from both analytical and digital methods are compared with similar study in the relevant literature.