[GRASS-user] v.in.ogr: shape files import trouble

GRASS GRASS user
,
1

Hi you all

I am facing with a shape files import problem.

I got a shape file, polygons in it got areas, but when I push them into grass using v.in.ogr several polygons lost their area and the only thing I get it’s a centroid, no boundary, no lines but simply a centroid.

QGis currently shows this shape correctly, so every polygon got his areas.

Same problem, if any and not my fault, occurs with grass6.2cvs and grass6.3cvs, debian testing OS.

Any suggestion?

thanx
raffaele

2

Raffaele Morelli wrote:

I am facing with a shape files import problem.

I got a shape file, polygons in it got areas, but when I push them
into grass using v.in.ogr several polygons lost their area and the
only thing I get it's a centroid, no boundary, no lines but simply a
centroid.

QGis currently shows this shape correctly, so every polygon got his
areas.

Same problem, if any and not my fault, occurs with grass6.2cvs and
grass6.3cvs, debian testing OS.

how does it look if you skip cleaning the data?

topology is not guaranteed then, but if the data is only for looking at
it might be ok.

v.in.ogr -c

Hamish

3

i think your file is not topologically correct...
Be sure about your data! More often the shape file have this problem if
they have nodes or boundaries not rightly overlapped.
Try to use tha snap threshold feature in v.in.ogr combined with area
option...
Cheers
Pierlugi De Rosa

--
GfoServices S.A.

Hi you all

I am facing with a shape files import problem.

I got a shape file, polygons in it got areas, but when I push them into
grass using v.in.ogr several polygons lost their area and the only thing I
get it's a centroid, no boundary, no lines but simply a centroid.

QGis currently shows this shape correctly, so every polygon got his areas.

Same problem, if any and not my fault, occurs with grass6.2cvs and
grass6.3cvs, debian testing OS.

Any suggestion?

   thanx
   raffaele
_______________________________________________
grassuser mailing list
grassuser@grass.itc.it
http://grass.itc.it/mailman/listinfo/grassuser

4

how does it look if you skip cleaning the data?

Same problem -c doesn’t affect resulting vector.

topology is not guaranteed then, but if the data is only for looking at
it might be ok.

v.in.ogr -c

tried with min_area and snap option, also imported without cleaning and later applying v.clean with several tools/paramenter settings.

I faced this problem some time ago when using v.patch (Maciej should remember about that) from those same files.
I guessed it was an overlapping shapes problem or, as Pierluigi suggests, an incorrect topology issue.

But, how can I get data displayed like in QGis? or can I at all?

raffaele

5

how does it look if you skip cleaning the data?

topology is not guaranteed then, but if the data is only for looking at
it might be ok.

v.in.ogr -c

v.in.ogr dsn=shape output=shapeout

this command without any other option seems to be ok, I am going to try with other files.

thanx
raffaele

6

On 12/03/07 11:54, Raffaele Morelli wrote:

    how does it look if you skip cleaning the data?

Same problem -c doesn't affect resulting vector.

    topology is not guaranteed then, but if the data is only for looking at
    it might be ok.

    v.in.ogr -c

tried with min_area and snap option, also imported without cleaning and later applying v.clean with several tools/paramenter settings.

I faced this problem some time ago / /when using v.patch (Maciej should remember about that) from those same files.
I guessed it was an overlapping shapes problem or, as Pierluigi suggests, an incorrect topology issue.

But, how can I get data displayed like in QGis? or can I at all?

Try v.external.

Moritz