[GRASSLIST:6609] surf.rst and segmax, npmin

Jose Gomez-Dans jgomezdans at gmail.com
Sat Apr 23 13:59:04 EDT 2005

I am trying to interpolate a DEM from an quasi-regular grid of the
region of interest (meaning that I have one data point per resolution
cell, roughly). I am using s.surf.rst (I can't get the data into GRASS
6.0), and I have noticed that if you look at the slope aspect angle
plot of the interpolated surface, the joining lines of the
segmentation procedure are clearly visible in some areas. I am able to
get rid of them by changing the npmin and segmax parameters (say,
segmax=200 and npmin=1000 yields good results). This however, greatly
slows computations, and these values are just trial and error, I don't
really know what set of values will be optimal.

The documentation mentions that if these lines are visible, npmin
needs to be increased, but is there some "recipe" or idea as to the
nature of these numbers?

Thank you very much!

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