[GRASS-dev] Large Polygon-datasets

[Hamish]

> I have a very large dataset containing about 300.000 polygones which I
> would like to import into GRASS using v.in.ogr
> 
> Is there a possibility to not build the topology during import, but
> afterwards. It runs nor about several hours now and does not provide
> more information than 
> Importing 300000 map features...
> 
> and nothing more. The maschine is very slow in response using the
> mouse.
> 
> Does anybody have some experience in using this kind of datasets?
> Thanks for any suggestions how to import the data.


Yes, I have seen this and IIRC there was a Florida Coastline import with
the same problem.

In all cases the polygons were all unbroken polygons with only one end
node breaking a single boundary line.


At the time, Radim wrote:
> Now I have just one idea, because the areas are probably isolated,
> it could be that exist one BIG boundary around all the map
> (I thing that something like that exists in ArcInfo),
> in that case, when this boundary is processed, it selects
> lines which could intersect it by bounding box, in that case ALL
> lines, and to check intersection of ALL segments of that BIG line
> with ALL segments of ALL other lines can take a very long time.

I think this case is why he wrote v.split.

here we go,
 http://thread.gmane.org/gmane.comp.gis.grass.user/7391/focus=7394
 http://thread.gmane.org/gmane.comp.gis.grass.devel/7417
 http://article.gmane.org/gmane.comp.gis.grass.devel/7400
 http://grass.itc.it/pipermail/grassuser/2005-April/028518.html
 http://grass.itc.it/pipermail/grass-dev/2005-March/017745.html
...


Hamish