[GRASS-user] Artefacts when interpolating DTM from Contour Lines with v.surf.rst

[Andreas Neumann]

yes, I am changing various values, including dmin. I get different sizes 
of the rectangular artefacts, but they never really disappear, 
regardless of the values I used. I still hope I can find a better 
parameter combination where the artefacts aren't visible.

Andreas

Andrea Ricci wrote:
> Andreas Neumann wrote:
>> Hello,
>>
>> I am trying to interpolate a raster DTM from contour lines. I like the
>> results from v.surf.rst, however, this algorithm, at least with my
>> settings seams to generate rectangular artefacts in the resulting DTM. 
>> See
>> a hillshade of my result at
>> http://www.carto.net/neumann/temp/hs_dtm_tension5_smooth2.png - if it
>> weren't for these artefacts I would like the results very much.
>>
>> Here are the parameters I used:
>> v.surf.rst input=hl layer=1 zcolumn=elev_m dmax=10 dmin=0.5
>> elev=dtm_tension5_smooth2 zmult=1.0 tension=5 smooth=2 segmax=40 
>> npmin=300
>> --overwrite
>>
>> The idea is to get a smooth, not too detailed DTM, hence the small 
>> tension
>> and higher smooth values.
>>
>> Are there any parameters or postprocessing steps that would help me 
>> remove
>> these rectangular artefacts? Or alternatively, are there better 
>> methods to
>> interpolate DTMs from contour lines?
>>
>> Thanks for any ideas,
>> Andreas
>>
>>
>>   
> Try with increasing dmin= 2 or try with other values. Normally, in case  
> of visible segmentation, this value must be increased.
> hope that's helpful
> Andrea Ricci

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