After finishing this project, I have learned some techniques of computing operations such as web-design and creation of websites, and computing programs of GIS such as Idrisi and Freehand. For doing the spatial analysis through uses of Idrisi program's techniques, I found some problems in production of images. However, the techniques such as "Assign", "Reclass", "Distance," and "Buffer" are easily managed and they are very useful to analyze spatial questions in specific regions.
Originally, I designed to use the operation "Multi-criteria evaluation" (MCE) to create two images, one of which should be combined to show locations associated with high soil degradation, over exploitation of vegetation, high chemical and physical deterioration of the soil, high water erosion, and high severity of wind efffects, and the other of which should show locations with completely opposite side of these factors. The reason to create them was to figure out where is most suitable for a broad range of vegetation's types and where is only for a single or few vegetation species even entirely not suitable for vegetation growth. However, as sizes of pixels in some layers were different from others', to combine all layers into one image were impossible. Finally, I decided to divide one image to two images. It means that the final outcome would be four final images come from the two to show the same purposes described above, but after creating them, the image was completely black even changes of different palette files. Hence, it suggested that there is no such areas associated with the criteria I set, and they were given up.
In the original layer shown the percentage of surface water in Africa, there were only two categories in its legend. One was represented 0% while the other was represented 100%, but categories between 0 to 100 were omited. Therefore, I needed to reclassify and set up categories which matched colors displayed in the image with the help of most recent maps of Africa. Because of lack of detailed legend in the original layer, the images related to surface water's layer may contain small error/problem.
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