Hi list,
Sorry to resurrect a reasonably old topic (following my mail), but I
have two questions on the r.param.scale module:
1 - I share Jasiewicz's concerns, the formula do not match the
litterature I got [0]
2 - My understanding is that the plan curvature (planc) can be
computed, but not the tangential curvature. Is it an easy task to
modify my local version of the code to include the tangential
curvature in r.param.scale ?
I know other modules, such as v.surf.rst, offer to compute the
tangential curvature, but I'd be glad to generate the different
curvatures I need using only one command.
Cheers,
Pierre
[0]: Hengl, T., Reuter, H.I. (eds) 2008. Geomorphometry: Concepts,
Software, Applications. Developments in Soil Science, vol. 33,
Elsevier, 772 pp. More precisely page 151.
2010/11/2 Jasiewicz Jarosław <jarekj@amu.edu.pl>:
Hi
while I modified r.param.scale for my purposes I noticed that some formulas
for curvatures differs from that I know:for example:
plan curvature: is
(2.0 * (b * d * d + a * e * e - c * d * e) /
pow(e * e + d * d, 1.5));probably shall be:
( (b * d * d + a * e * e - 2.0 *(c * d * e)) /
pow(e * e + d * d, 1.5));profile curvature: is
return \(\-2\.0 \* \(a \* d \* d \+ b \* e \* e \+ c \* e \* d\) / \(\(e \* e \+ d \* d\) \* pow\(1\.0 \+ d \* d \+ e \* e, 1\.5\)\)\);probably shall be:
return \(\- \(a \* d \* d \+ b \* e \* e \+ 2\.0\* \(c \* e \* d\)\) / \(\(e \* e \+ d \* d\) \* pow\(1\.0 \+ d \* d \+ e \* e, 1\.5\)\)\);Of course threre could be reasons why little different formulas are used but
I do not see any.This formulas is in grass 6.4, 6.5 and 7.0 and I assume in older version
too.regards
Jarek
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
--
Scientist
Landcare Research, New Zealand