[GRASS5] Re: [5.7] remove islands and U-dangles?

[Hamish]

So it's clear: here's a picture to describe what I am trying to do.
(d.vect map=land cat=1-100000)


The holes/islands/areas-without-centroids are (real) islands in rivers.
I removed the rivers with 'v.extract -d list=1-100000', but the inner
areas remain as artifacts. (as from original shape file)

I am trying to extract a vector to tag as the coastline at 0 elevation
for a DEM interpolation. These left over islands can be very high up in
the mountains and make giant holes to sea level in the DEM.

'd.vect cat=1-100000' works great, I don't mean to change that.

What I need to do is remove those areas from the file altogether.

guesses at solutions:
. If there (is?) was a tool to add centroids to all areas/voids, I could
run 'v.extract -d' on it and be done?
. Or convert inner boundaries to lines..?
. Maybe dissolve needs to be smarter?


The QGIS polygon_0 layer should work well to show me where they are;
some of the areas are tiny and very hard to find when the rest of the
vector is shown. I would still have to use v.digit to remove them by
hand though if no other tool was available. (doing this can cause
v.digit to SegFault, BTW)

For more headaches, there is at least one spot with an island in a lake
on an larger island in a river.




thanks,
Hamish
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