[GRASS-user] Patch raster maps very slow - Is there a way to speed this up?

Hamish hamish_b at yahoo.com
Mon Jan 11 21:44:58 EST 2010

stephen wrote:
> I have generated DEM tiles (65ish) from LIDAR data in its
> natural projection NC state plane feet (the area covered is
> about 300 squared miles).  I have reprojected them into UTM 17
> nad 83.  These DEMs are 1m resolution.

so the region is like 50000 x 50000 rows,columns?

> I am using r.patch and it has been running for three
> days now and it is 45% done...  Would it be faster to
> stop this process,

if it is half done and seems to be working, if it were me I'd
just renice it to low priority & let it finish.

> patch them in there native projection and then reproject them
> to UTM?

that's probably good policy regardless.

another faster way might be to split up the tiles into 4
quadrants and run the r.patch in each of those then finally
just patch the last 4 quadrant maps together. that should
probably be done in the native projection to avoid chopped off



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