[GRASS5] v.digit topology question

Michael Barton michael.barton at asu.edu
Fri Oct 31 07:37:13 EST 2003


Thanks again. Your replies are helping quite a bit in making GRASS 5.7 
more useable.

On Thursday, October 30, 2003, at 07:43 PM, Radim Blazek wrote:

> On Thursday 30 October 2003 10:21, Michael Barton wrote:
>> After considerable futzing, that is where I am at now. When I first
>> digitized this, it happened to be in several separate segments (green
>> "x" at intersections). I eventually ran v.clean, separating all
>> segments, followed by v.build.polylines to put them together into a
>> single boundary (one red "x" at the closing intersection). However, I
>> had to do a v.out.ascii, edit the ascii file to get rid of some tiny
>> segments, followed by a v.in.ascii to finally get to a single boundary
>> line.
> Small dangles can be removed by v.clean tool=rmdangle

I did this. This is why I was surprised to find these in the ascii 
files. In fact, they may be dangles that overlapped part of the 
"correct" polygon. I also turned on rmdup (to remove such duplicates) 
in v.clean. So I don't know why they still were hanging around.
>> The polygon still doesn't show up as a filled area.
> Areas are filled in d.vect, not in v.digit.

Sorry, I wasn't clear. It doesn't show up in v.digit as a filled area. 
I can't tell if it is an area or not in v.digit (because I haven't 
successfully made one yet to see how it looks), so  I am using v.digit 
to see if I've created an area or not.

>> If it helps figure out what may be going on, nothing happens when I
>> click the show attributes button and select either the polygon or a
>> centroid I created.
> You can query only primitives (point,line,boundary,centroid) not areas
> in v.digit.

Again, I guess I wasn't clear. I was clicking on both the boundary and 
the centroid and nothing happened. Because I haven't yet been able to 
make an area, I can't select one to query (though it's good to know 
that I shouldn't bother). I *thought* that once in the past when I 
queried something I made I got an information box, but this is not 
happening on these figures.

As an aside, I successfully exported the polygon to GRASS 5.0.x using 
the v.out.ascii -o command. After running v.build, I opened it in 
v.digit (ver. 4.3), added a centroid, and voila had an area.

I must be missing something somewhere in trying to do this in GRASS 5.7.


C. Michael Barton, Professor
Department of Anthropology
PO Box 872402
Arizona State University
Tempe, AZ  85287-2402

Phone: 480-965-6262
Fax: 480-965-7671

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