[GRASSLIST:641] Re: overlapping polygons from bad shapefile

[Hamish]

> Received a geology map of our survey area in shapefile format, but
> some of the  polygons are overlapping. Upon import into grass with
> v.in.ogr, the  overalpping polygons are split according to the rules
> of topology at nodes (i  think). 
> 
> Here is a link to the results of a quick `d.vect -c`
> 
> http://169.237.35.250/~dylan/temp/overlap.png
> 
> The red arrow points to an area where an underlying formation overlaps
> with  overlying Quaternary sediments -- rather common in reality, but
> difficult to  capture without overlapping polygons...
> 
> I am interested in classifying this map, and rasterizing the result.
> However,  v.to.rast does not quite produce the output that I would
> like in areas where  polygons are overlapping. i.e. v.to.rast is using
> the attribute from the  "lower" polygon where the two geologic unit
> polys are overlapping. Is there  anyway, short of manually removing
> these trouble polygons, to make v.to.rast  use the attributes
> associated with the "uppermost" overlapping polygon?
> 
> Any ideas would be appreciated!

try loading in with:

v.in.ogr -c
 or
v.external


Hamish