[GRASS-user] GRASS63cvs v.rast.stats reports zero for many CATs

[Brandon M. Gabler]

Thank you for the tips, Maciej,

On a hunch, prior to your email, I did re-try the exercise with a  
shorter prefix (s16 instead of slope16), and this solved the problem.  
I think column width may have been the problem. I had inspected the  
values at those locations, and they had normal slopes (7, 6, or 9  
degrees, etc.).

Curious problem, solved thanks to suggstions from the grasslist as  
always!
Brandon

On Apr 7, 2007, at 5:24 AM, Maciej Sieczka wrote:

> Dylan Beaudette wrote:
>> On Friday 06 April 2007 13:36, Brandon M. Gabler wrote:
>>> Fellow GRASSers -
>>>
>>> I am using GRASS 6.3 cvs, the Kynge's build, and I have an issue
>>> using v.rast.stats on a raster of slope. Many (n>100) of my
>>> archaeological sites, which are all polygons, produced 9 columns of
>>> zeros for the slope stat calculations.
>
> Can you provide a GRASS location containing the data necessary to
> reproduce your problem, and the exact v.rats.stats command? Otherwise
> it's hard to say what could be the problem.
>
>>> The oddest part is that I successfully calculated elevation stats
>>> from a DEM raster using the same v.rast.stats command. The slope
>>> raster was produced directly from the DEM, so resolution, etc. are
>>> exactly the same.
>
> Is it possible that the slope raster has really small values at these
> locations, ie. with numbers after 10th decimal place? There is a note
> in the v.rast.stats (it's a shell script), line 165:
>
> #check if DBF driver used, in this case cut to 10 chars col names:
>
> Propably Markus (script author) can explain why this is necessary.
>
> Maciek