[GRASS-user] r.proj input output comparison

Hi,

A specific, and general question on reprojection:

I've changed the resolution of a raster from 1000 to 2 (UTM15) using r.proj. The summary statistics are very similar for both rasters which is reassuring. However, how do I display/compare both rasters so that I can see which of the higher resolution pixels have the largest/smallest differences (for example) with respect to the original 1000 m data?

The importance of "knowing your projections" was discussed in the UTM concepts thread, but in general how would one compare reprojected maps to evaluate projection related differences?

Or, if I have a set of images, vectors, and raster that "line up" correctly in one projection, wouldn't they be self-consistent when reprojected, although somewhat distorted with respect to the original?

Thanks.

M