The planimetric accuracy of the delivered IKONOS images was assessed using the GCPs. The errors vary proportionally to the terrain height and are much larger than the error specified by Space Imaging for Geo, since the latter does not include errors due to relief and the inflated ellipsoid, as mentioned above (see version 1 in Table 2). The accuracy of the orthophotos using the two sensor models mentioned in Section 5 was also assessed with the GCPs. They were measured in the orthophotos by taking their known coordinates from one channel of the original image and transferring them semiautomatically in all orthophotos by least squares matching. These pixel coordinates were transformed to the EGSA system and their height interpolated in the DEM. The later shows just the DEM accuracy including effects from orthophoto errors (e.g. planimetric shifts cause height errors). The results of this accuracy analysis are listed in Table 2. Version 5 using Kratky’s PMF with 38 GCPs is slightly more accurate than version 4, using the same model with 28 GCPs. This is natural since in the first case, no independent check points existed, and the polynomial terms were fitting