The uses of the River Nile can be improved in transportation, tourism and other important fields by using
Geographical Information System (GIS) and Remote Sensing techniques as creating River Nile base map for monitoring
River Nile resources. In order to develop an updated base map for River Nile in Egypt, it was necessary to address, review,
assesses and evaluates the available different free sources satellite images. In this paper, four study areas over Egypt were
chosen and definite points were observed for those areas using GPS techniques. The same specified points were determined
on the available free satellite images. Assessment for free sources satellite images, in terms of horizontal accuracy, and
depending on the available images resolution, has been evaluated. The obtained results of Root Mean Square Error (RMSEr)
for horizontal coordinate differences in small areas vary from 1.57 m to 5.06 m, and large area varies from 8.52 m to 9.15
m. Image registration techniques were applied using two dimensional transformations process in the previous four study
areas between the two free sources satellite images (Image-to-Image registration) and between satellite image and GPS
points (Image-to-Ground registration) to get the register image points with suitable accuracy comparable with GPS
accuracy and images resolution. The transformation parameters (Scale (s), Rotation (θ) and Translations (ΔX, ΔY)) are
calculated for the areas under consideration. The Root Mean Square Error (RMSEr) obtained from the transformation
process in small areas varies from 1.94 m to 2.86 m and in large area varies from 7.428 m to 8.586 m. Then these calculated
transformation parameters used to transform other points onto the required system. This approach can be used in different
areas which have lack of GPS observed points to calculate semi-ground points from transformed measured free imagery
points with suitable accuracy compared with the accuracy of GPS and images resolution. Finally, using free sources
satellite images with Geographic Information System Application to building an updated base map for River Nile in Egypt. |
