[GRASS-user] GRASS raster curvature analysis type

[Markus Neteler]

On Tue, Sep 13, 2016 at 4:02 PM, Anna Petrášová <kratochanna at gmail.com> wrote:
> On Tue, Sep 13, 2016 at 7:58 AM, Helmut Kudrnovsky <hellik at web.de> wrote:
>> georges wrote
>>> Hello,
>>>
>>> I would like to know whether raster curvature analysis in GRASS
>>> is Gaussianor Mean curvature analysis?
>>> https://en.wikipedia.org/wiki/Gaussian_curvature
>>> https://en.wikipedia.org/wiki/Mean_curvature
>>>
>>> This GRASS 7.2 manuals page mentions that raster curvature analysis can be
>>> conducted in direction of steepest slope and in the direction of the
>>> contour tangent, therefor distinguishing two curvature options: profile
>>> and tangential.
>>>
>>> Still are these two Gaussian or Mean curvatures?
>>>
>>> Thank you for the reply.
>>
>> I can't tell you directly which algorithm is used.
>>
>> fortunately GRASS GIS is open source; so maybe have a look at the source
>> code to check:
>>
>> r.slope.aspect:
>>
>> https://trac.osgeo.org/grass/browser/grass/trunk/raster/r.slope.aspect/main.c
>>
>> or
>>
>> r.resamp.rst
>>
>> https://trac.osgeo.org/grass/browser/grass/trunk/raster/r.resamp.rst/main.c
>>
>> HTH
>
> also r.param.scale:
> https://trac.osgeo.org/grass/browser/grass/trunk/raster/r.param.scale/


You find the formulas used for the r.slope.aspect and r.resamp.rst
implementations in the GRASS book, 3rd edition, 2008, Springer,
Appendix pages 371-376.

Best,
Markus