Hi Jamal, After a quick internet search to find out what Cellular Automata is and checking the routines available in ENVI it doesn't look like there is a built-in function emulating CA. I'm not that familiar with CA but you may have a look at the 'decision tree' for some possiblilities. As for the OD, again there is no built-in function for that. If you have equations for either one you may be able to create some functions using IDL code that can then be integrated into ENVI.