[GRASS-user] nulls left by r.surf.nnbathy

[Nick Cahill]

I'm trying to create a dem from digitized contour lines with  
r.surf.nnbathy. I've started with vector contour lines, converted  
them to a raster with v.to.rast, then interpolate these using  
r.surf.nnbathy. The output looks good, except that it is speckled  
with random-looking null cells, as in the enclosed screen shot (white  
are nulls)


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I can't figure out what is causing these: some are on a contour line,  
some are between contours; I don't see an obvious pattern. Is this a  
known issue with r.surf.nnbathy, and if so, is there a workaround?

On a related note, when I've tried to fill the nulls with  
r.fillnulls, the program crashes gis.m with a segmentation fault,  
leaving a couple temporary rasters and a mask.

I'm running GRASS 6.3, on Mac OS X 10.4.8, using William  
Kyngesburye's excellent binaries (dated 9/29/06, maybe not the most  
recent build). I built the binary for nnbathy myself; perhaps this is  
the problem. How would I test that?

Many thanks for any help anyone could offer --

best to all,

Nick Cahill
University of Wisconsin-Madison