I'm working on that and autostudy the theme, I view nice results aplying Directional Filter in differents angles to a DEM ,,, also computing Principal Components to all bands, and analyzing R-PC1 G-PC2 B-PC3. That all in Aster ... well a great way is making an Anglyph with bands 3B and 3N and analyzing with stereo glasses. cheers Jose Manuel Lattus