[GRASS-dev] Re: r.walk, r.cost & r.drain patches posted

[Michael Barton]

On Dec 22, 2008, at 2:33 PM, Colin Nielsen wrote:

> I have fixed that and other errors reported by Dylan. New patches are
> available on ticket #399.
>
> Thanks.
> -Colin
>
> On Sat, Dec 20, 2008 at 11:47 AM, Michael Barton <michael.barton at asu.edu 
> > wrote:
>> Colin,
>>
>> I applied your patches. Those for r.cost and r.walk went OK. The  
>> one for
>> r.drain did not compile. Here is the error:
>>
>> cmb-MBP-2:r.drain cmbarton$ make
>> gcc
>> -I/Users/cmbarton/grass_dev/grass6_src/dist.i386-apple-darwin9.6.0/ 
>> include
>> -arch i386 -Os    -I/Library/Frameworks/GDAL.framework/Versions/1.6/ 
>> Headers
>>   -DPACKAGE=\""grassmods"\"
>> -I/Users/cmbarton/grass_dev/grass6_src/dist.i386-apple-darwin9.6.0/ 
>> include
>> -o OBJ.i386-apple-darwin9.6.0/main.o -c main.c
>> main.c: In function 'drain_cost':
>> main.c:697: error: 'dir_name' undeclared (first use in this function)
>> main.c:697: error: (Each undeclared identifier is reported only once
>> main.c:697: error: for each function it appears in.)
>> make: *** [OBJ.i386-apple-darwin9.6.0/main.o] Error 1
>>
>> Michael
>> ____________________
>> C. Michael Barton, Professor of Anthropology
>> Director of Graduate Studies
>> School of Human Evolution & Social Change
>> Center for Social Dynamics & Complexity
>> Arizona State University
>>
>> Phone: 480-965-6262
>> Fax: 480-965-7671
>> www: <www.public.asu.edu/~cmbarton>
>>
>>
>>
>> On Dec 15, 2008, at 1:20 PM, Colin Nielsen wrote:
>>
>>> As the two people who have expressed the most interest in these
>>> modules, I thought I would let you know that I have opened a ticket
>>> and attached patches with my code updates
>>> (http://trac.osgeo.org/grass/ticket/399). When either of you has the
>>> chance, I'm looking forward to hearing about your tests of them.
>>> Thanks.
>>>
>>> -Colin

Colin,

I tested your new patches to r.cost, r.walk, and r.drain using  
elevation.dem from Spearfish and some of the archsites as starting  
points. In spite of the patch errors, all ran fine.

It seemed like all ran faster, but maybe that was my imagination. The  
backlinked and non-backlinked paths made on a cost surface from  
running r.cost on a slope map are very similar to each other.

The backlinked and non-backlinked paths made on a cost surface using  
r.walk are very different from each other, though the non-backlinked  
path on an r.walk surface was very similar to the backlinked and non- 
backlinked paths on an r.cost surface. The backlinked path looked a  
little odd, transecting rugged terrain in almost a straight line. In  
fact the backlinked paths from r.walk are nearly straight lines. Is  
this a reasonable result?

One fairly serious problem is that the backlinked paths are  
discontinuous, with lots of gaps; the non-backlinked paths are  
continuous without gaps.

I've posted screenshots of the tests at: http://www.public.asu.edu/~cmbarton/files/grass_cost/

Thanks for working on these modules.

Michael