dem analysis

Discussion created by sawaske on Nov 6, 2013
Latest reply on Dec 2, 2013 by mark909

I'm having trouble with what I think should be a relatively straightforward analysis of 10 meter dem data.  If you have a minute, could you offer any suggestions. 

I am trying to calculate a sort of "exposure" score for every cell in a raster.  The basic idea is to compare the value of each raster cell with those nearby(200-400m radius).   

E1= (# cells in surrounding area with elev.< cell  elev.)/(# cells in surrounding area with elev.> cell  elev.)
E2= (sum[cell elev.-(elev.of surrounding cells<gage  elev.)])/(sum[(elev.of surrounding cells>cell  elev.)-cell elev.])

For both indices, larger values represent locations with greater exposure and smaller values represent more protected, less exposed locations.  For instance, the E1 value for a location on top of a cone would be infinity, while that for the low point of an inverted cone would be 0.  I've been able to compute these indices for a small number of point locations using a combination of buffer and zonal tools.  Unfortunately, I'm now trying to perform this analysis for every cell in a much larger area(2-3 thousand cells) and my original method is no longer feasible.

I would greatly appreciate any suggestion you could offer.