Abstract:
This study is oriented to extract the heights of buildings around the International Khartoum Airport and to detect any obstacles. Aerial photographs were used to extract these heights by creatig Digital Elevation Model (DEM). Data has been processed in two ways : using Ground Control Points (GCPs) and without measured GCPs depending on exterior orientation parameters.
The procedures adopted in this study are applied on aerial photographs in two different regions (Inner Horizental Surface and Outer Horizental Surface). Results of heights of extracted DEM in Inner Horizental Surface gave elevation of ground above the buildings. So these results are not acceptable.
Another aerial photographs in Outer Horizental Surface were processed, and results were logical. Then accuracy of DEM was checked with observed heights from feild using traditional survey methods.Buildings in images were compared in the field , two of them were choosed for checking heights in extracted DEM.
It was found that the maximum deviation between the phisical heights and computed one is 2.702 meter when using Ground Control Points (GCPs) and was 2.931 meter without collecting GCPs. This deviation is acceptable according to minimum clearence height (30.48 meter).
