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Thanks for your answer! I have more than 100 polygons. I will try the overlapping option "AnalysisTools">"Overlay˙">"Intersect". Thanks again!

Hi, I need help to analyze some data. I have a shapefile with several attributes that correspond to polygons. Some of these polygons do not overlap, but others overlap. The polygons have several overlapping case, for example: - A polygon can exactly overlap other, or more than one. - But it may happen that one polygon is overlapped by other polygon in a location and is overlapped by three polygons in another location and in other location it is not overlap by any polygon. So what I want to do is an analysis of overlapping polygons, resulting an image where no overlapping polygons appear green, the polygon that has more than one overlay appear with different kinds of red. And, the polygon having different amounts of overlap would have different shades of red and green (in places where it had not overlap). This has to be possible to do but I 'm having some difficulty. Can anyone help me on this problem? I have done several searches but I did not find the solution. Thanks for your help .

Thanks for your answer, it was very useful!! But I still have a doubt. With your links I can't create a DTM with the parameters that I refer in my first post. Am I correct? Thanks, Andre

*and Vertical resolution Many thanks, Andre

Hello people, I need to create a DTM with this specifications: - Post spacing - Vertical accuracy - Horizontal accuracy - Confidence level - Data Classification Integriry Level - Maintenance period How can I do it in ArcGIS? Anyone know how to do it or know any tutorial? Many thanks, Andre

Thanks! I will try that way!

Hello! Anybody can help me with a problem related to cartographic minimum unit? How to change the cartographic minimum unit of a raster image in ArcGIS? for example to 5 hectares? Thanks for your help!

In ENVI 4, Classification > Post-Classification > Confusion Matrix > Using Ground Truth ROIs, ENVI 4 tells that need a Classification Image and my NDVI difference image doesn't fill this requirement. -> that gives me an error because is a NDVI image and doesn't have classification (I think is because of that...)

Hi! I have a doubt related with NDVI images. How make accuracy from a NDVI difference image? How to create an error matrix with the classes "increase", "decrease" and "no change"? I created train sites in the right places but now I don't know how to create an error matrix on ENVI 4 or ArcGIS (if it is possible). In ENVI 4, Classification > Post-Classification > Confusion Matrix > Using Ground Truth ROIs, ENVI 4 tells that need a Classification Image and my NDVI difference image doesn't fill this requirement. What can I do? With ArcGIS this can be made too? And with GDAL? Thanks a lot!!