[GRASS-dev] question about any July changes in hydrology functions

[Michael Barton]

Thanks Glynn,

We've been diffing our scripts to the extent possible--i.e., once we started
committing them to the SVN and haven't found anything obvious yet.

Helena also mentioned r.neighbors as a possible culprit, as I'd forgotten to
mention that we also use this to smooth results.

Michael


On 8/1/07 12:31 AM, "Glynn Clements" <glynn at gclements.plus.com> wrote:

> 
> Michael Barton wrote:
> 
>> Beginning sometime in the 1st half of July, we¹ve started getting some weird
>> artifacts in surface process models that we¹ve been developing using r.flow,
>> r.slop.aspect, and r.mapcalc. The results are linear zones of deposits that
>> seem to follow cell grid lines. This wasn¹t happening previous to early
>> July. We¹ve scouring our scripts and so far can¹t find anything to account
>> for this changed behavior. It acts like some kind of dynamic resolution
>> change artifact, but we are not doing anything to cause this AFAICT.
>> 
>> It is probably something squirrelly in our scripts that we just  haven¹t
>> seen. But I thought I go for a long shot and ask if there have been any
>> changes that might affect the behavior of r.flow or r.slope.aspect recently.
>> I didn¹t see anything obvious in the commit list archives, but may have
>> missed a library change of some kind.
> 
> $ cvs diff -D 2007-07-01 -D 2007-07-15 raster/r.mapcalc raster/r.slope.aspect
> raster/r.flow
> cvs server: Diffing raster/r.mapcalc
> cvs server: Diffing raster/r.slope.aspect
> cvs server: Diffing raster/r.flow
> 
> Assuming that your dates are correct, it isn't the programs. Extending
> the comparison to lib/{gis,vector,bitmap,btree,rowio,segment} (the
> only libraries which those programs use directly) doesn't show
> anything which looks remotely relevant.
> 
> I can only suggest checking out and compiling "before" and "after"
> versions, and examining any intermediate data produced by your
> scripts.

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton