On Aug 17, 2007, at 5:21 AM, Paul Kelly wrote:
On Fri, 17 Aug 2007, Helena Mitasova wrote:
[Interesting/impressive test results...]
which brings me to the main question - are there any objections to
make dmax default value
as large as the region to make sure that it does not add any points
(currently it is set to 1.25 resolution value which is obviously
not enough)?
I have been trying to eliminate this parameter for years
as it usually causes more problems than it solves.
For 7.x perhaps you could drop both the dmin and dmax parameters,
and add a note to the man page suggesting that the user preprocess
their contour data with v.generalize to resolve issues with closely-
spaced points, before running v.surf.rst?
I will eliminate dmax in GRASS7 (if I still remember it) but dmin
needs to stay.
v.generalize applies only to lines or area boundaries
so the preprocessing can be used only for contours -
dmax applies only to contours (it does the same thing as v.to.point -
vi )
- it does nothing if your input are scattered points.
We still need dmin for preprocessing of scattered points and for
elimination of points
that may be too close to each other due to density of contours on
steep slopes.
Profiles that you may get from real time kinematic survey or single
beam sonar
have similar problem as contours with points being much denser along
the profile compared
to the distance between profiles, but they would require
generalization in vertical plane rather
than the horizontal plane.
v.generalize should also help with v.surf.idw and kriging in case
somebody wants to use
those methods to grid from contours or isolines.
Helena
Just a thought
Paul
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