The Digital Terrain Model (DTM) is considered a common tool in producing topographic maps, orthophotos and civil engineering projects besides other different engineering applications. As a result, many software packages were developed and used to produce (DTM ) from different sources like filed surveys, scanned topographic maps and stereo photos exposed from air or space .
This research is devoted to evaluate the most suitable and accurate in producing digital elevation model from two different sources' the first source is ground surveys for the area north of Iraq (Iraqi Iran borders ) by using Global Position System (GPS) the second source is the aerial photos. Thebasic topic is producing Digital Elevation Modal (DEM), and orthorectify images, and hownew technique and software in aerial photogrammetrycanbe useful to produce topographic maps and also, getting idea with detail about what these software need to run aerial triangulation.
The (DTM) has been produced from strip of aerial photos in the North of Iraq (Iraqi Iran borders). Also, theorthometric corrections for these photos have been done so that we can use these images to produce topographic map. The type of the used camera was (Ziess rc10_1975) and the date for these images is 1975, the scale of these photos is 1/30000, and the averageof flying height is 4500m above mean sea level.
The software we used in this research was ERDAS Imagine LPS (Lieca photogrammetric system).