Proper algorithms for computing slopes for global/polar DEMs?

Have you thought about a Lambert Conformal projection?  I'd think you could 
adjust the projection parameters to get a pretty nice grid over Alaska.  I'm 
sure the mesoscale modelers at UA-Fairbanks have worked this out.

Clint

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On Fri, 20 Feb 2015, Jonathan Greenberg wrote:

 r-sig-geo'ers:

 We're trying to figure out a good algorithm for computing topographic
 slope
 for Alaska, which is both huge and near the pole.  Our DEM is currently in
 geographic coordinates, but we need slope over a fixed distance (change in
 elevation vs. horizontal meters).  The issue is, there is no projection to
 switch this to to get an accurate set of slope calculations.  Of course
 with degrees, the X and Y distances change over the globe -- so the
 horizontal distances will be variables from one window to the next.  I
 have
 seen various solutions published, but I wanted to see if someone knows of
 a
 decent coded-up algorithm for this.  Thoughts?

 Some background:
 http://gis.stackexchange.com/questions/14750/how-to-use-srtm-global-dem-for-slope-calculation/40464#40464

 --j

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