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<span style="font-weight: bold;">On Thu Jun 26 15:31 , Moritz Lennert <mlennert@club.worldonline.be> sent:<BR>
<BR>
</mlennert@club.worldonline.be></span><blockquote style="border-left: 2px solid rgb(245, 245, 245); margin-left: 5px; margin-right: 0px; padding-left: 5px; padding-right: 0px;">On 26/06/08 08:49, Richard Chirgwin wrote:<BR>
> Moritz Lennert wrote:<BR>
>> On 25/06/08 02:46, Richard Chirgwin wrote:<BR>
>>> Hi all,<BR>
>>><BR>
>>> 1) v.overlay question<BR>
>>><BR>
>>> I have three maps: two area vectors (A and B), and a v.overlay result <BR>
>>> (C). Is there a simple way to assign the percentage of areas in (A) <BR>
>>> covered by the overlay (C)?<BR>
>><BR>
>> Vector solution:<BR>
>><BR>
>> <a href="parse.pl?redirect=http%3A%2F%2Flists.osgeo.org%2Fpipermail%2Fgrass-user%2F2008-June%2F045290.html" target="_blank"><span style="color: red;">http://lists.osgeo.org/pipermail/grass-user/2008-June/045290.html</span></a><BR>
>><BR>
>> Moritz<BR>
>><BR>
> Moritz,<BR>
> <BR>
> This led me straight into an oddity. One of my vectors is created by <BR>
> buffering around points.<BR>
> <BR>
> The source map was a set of 800 points. V.buffer runs successfully, and <BR>
> when it ends, the new areas display without problem. However, when I run <BR>
> v.db.addtable, there are only 18 categories - any ideas?<BR>
<BR>
As GRASS is topologically clean, areas cannot overlap. v.buffer, <BR>
therefore, fusions those buffers that do. So if your 800 points are <BR>
close enough to each other to make the buffers overlap, they might <BR>
result in only 18 distinct polygons. This should be visible when you <BR>
display them.<BR>
<BR>
Moritz<BR>
<BR>
Moritz,<BR>
<BR>
Alas, no. These are small polygons - there is one area where overlap exists, but there are still hundreds of distinct polygons. This is busting my brain...<BR>
<BR>
Richard<BR>
<BR>
<BR>
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