Digital orthoimages are proving to be suitable for a variety of mapping,
Geographic Information Systems (GIS) and environmental monitoring
tasks. The quality of the extracted data from orthoimages depends mainly
on the accuracy of the input data and the used mathematical models. The
availability of the Egypt Sat-1 satellite images provide valuable source of
remote sensing data in Egypt. Egypt Sat-1 is the first Egyptian earth
observation satellite which was successfully put in orbit on 2007. The main
aim of this research is to represent a rigorous sensor model approach
applied to Egypt Sat-1 image for orthoimage productions. For this study
an image level 1A from Egypt Sat-1 satellite captured in 2009 and a
topographic map, dated 1991, at scale 1:25,000 of the region of Assiut city
and the surrounding are used.
Orthoimage are generated in two parallel stages. The first stage is
generation of Digital Elevation Model (DEM) and the second stage is
developing mathematical model for an image-to-object relationship. The
results of these two stages are integrated to generate the orthoimage
proposed in two steps. The first step is the determination of image
coordinates (in the original image plane) corresponding to the DEM grid
points. The second step is assigning a gray value for these pixels. The
results of this study demonstrate the possibility to orthorectify Egypt Sat-1
images to sub-pixel accuracy. Orthoimages that were generated from
Egypt Sat-1 satellite images can contribute significantly to image map
production and to GIS applications.