[GRASSLIST:7547] vectorisation - vertex limit?

[Martin Rutzinger]

Hi!

I'm working on the object extraction out of Laser-DSMs. The challage is to find
a workflow with opencource (At the moment I'm working with
grass-6.1.cvs-i686-pc-linux-gnu-14_05_2005).
The Problem is not the process making polygons (This is just another step in my
workflow. Sorry if I formulated not exactly).

The Problem is the vectorisation with r.to.vect: The resulting vector (lines) I
get is not "finished" when displaying it (bottom part is missing). Further
analysis are not possible with this vector - always getting the error:
ERROR: Cannot open old vector mwin_vector1 at schlesi on level 2.

If I look into the GRASS database there are only three files of this vector
generated (coor  head  hist).
For me it seems like a limit in the vector-data-model (?!?), because everything
works fine with smaller regions.


Thank u 4 helping
Martin


Hi Martin,

On Wed, Jul 13, 2005 at 02:23:09PM +0200, Martin Rutzinger wrote:
> Hi all!
>
> I try to vectorize a thinned (r.thin) raster map with r.to.vect. After that I
> build the topology and create polygons

Question: why do you run r.thin if you want polygons?

> with v.build.

There is no need to run v.build, this is done by r.to.vect.
If not, your GRASS version is probably very old?

Perhaps you try without r.thin (which is used from *line* thinning).
For me it worked well so far.

Markus

> This works fine for small
> regions, but if I choose a larger one the vectorisation is not finished
> properly. It seems like r.to.vect starts at the top of the region and finishes
> if a certain value of vetices was made. I can visualise the result, but I
can't
> built the topology with this vector (ERROR: Cannot open old vector
> mwin_vector1 at schlesi on level 2).
>
> I zoomed into the extent of the unfinished vector and tryed again:
>
> Building topology ...
> 42238 primitives registered
> Building areas:  100%
> 0 areas built
> 0 isles built
> Attaching islands:
> Attaching centroids:  100%
> Topology was built.
> Number of nodes     :   37573
> Number of primitives:   42238
> Number of points    :   0
> Number of lines     :   42238
> Number of boundaries:   0
> Number of centroids :   0
> Number of areas     :   0
> Number of isles     :   0
>
> Is there a limit of primitives around 42238 in the vector format?
> Is it possible to handle larger vectors?
>
> thank you
> Martin