[GRASS-user] Encountering an error importing shapefiles with v.in.ogr

[Moritz Lennert]

On 22/03/07 10:14, Raffaele Morelli wrote:
> 2007/3/21, Thomas Adams <Thomas.Adams at noaa.gov 
> <mailto:Thomas.Adams at noaa.gov>>:
> 
>     Raffaele,
> 
>     After further testing, I do see the same problem you have had,
>     namely,"(some) areas which are not available after using v.in.ogr." This
>     is very apparent if I randomly color the polygons — some do not get
>     filled. Also, if I do a v.to.rast conversion, I get holes in the newly
>     created raster.
> 
>     Does anyone have thoughts on this?
> 
>     Regards,
>     Tom
> 
> 
> Did you try patching adjacent shapes (2 or more) coming from ArcGIS and 
> see what happens to the resulting?
> In this case I see some polygons lost area, even if each input shape is 
> correctly displayed.
> 
> Can you do this further test?
> 
> Cleaning the result shape using a simple
> v.clean input=x output=x_clean tool=bpol,rmdupl error=err (as suggested 
> in v.clean man pages to deal with vector originating from shape files)
> gives a better result but still I have polygons without area.

You can try to rerun the entire cleaning operation that v.in.ogr uses, i.e.:

v.clean in=inmap out=outmap_clean_vinogr
tool=snap,bpol,rmdupl,break,rmdupl,rmsa,chdangle,rmdangle,chbridge,rmbridge
thresh=0.000001

and maybe play around with the thresh parameter, depending on your 
projection and data resolution.

Moritz