Hi all, I'm not sure if my terminology is familiar but I'm trying to do a "moving window" analysis (ie a spatial filter or kernel) on a 2-D array representing elevation. For example, a 3x3 window centered on each cell is used to calculate the derivate slope of that cell. Can this easily be implemented using numpy? Currently I have tried implementing in pure python loops (too slow) and c++ (fast but more difficult to compile, distribute, wrap in python calls, etc). I think a good solution would be to leverage numpy which is both fast and and easy package for end users to install. An example of the C++ code I'm trying to emulate is at http://perrygeo.net/download/hillshade.html . Does anyone have any tips or examples out there? Where should I start researching this? -- Matthew T. Perry http://www.perrygeo.net