<br><br><div class="gmail_quote">On Wed, Mar 30, 2011 at 11:14 PM, Richard Chirgwin <span dir="ltr"><<a href="mailto:rchirgwin@ozemail.com.au">rchirgwin@ozemail.com.au</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div><div></div><div class="h5">On 30/03/11 9:21 PM, <a href="mailto:grass-user-request@lists.osgeo.org" target="_blank">grass-user-request@lists.osgeo.org</a> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Hi all,<br>
<br>
I'm trying to use v.delaunay to get the lines connecting centroids in<br>
thiessen polygons because I need to compute some statistics on the length of<br>
those segments.<br>
I'm facing a problem that maybe somebody could help me to solve.<br>
<br>
Basically I run v.delaunay with the -l option to get lines instead of the<br>
polygons, I get the resulting vector, but there is no attribute tables<br>
associated to it.<br>
My idea was to run v.db.addtable to create a new empty attribute table, then<br>
v.category to assign cat numbers and the v.to.db to compute and add to the<br>
attribute table the parameter I need (ie the length).<br>
The problem is that when I run v.category nothing happens, and the attribute<br>
table remains empty.<br>
<br>
Am I missing somethng?<br>
<br>
Any help appreciated.<br>
<br>
Ing. Andrea Pogliaghi<br>
Milano - Italy<br>
</blockquote></div></div>
Thoughts ...<br>
<br></blockquote><div><br>Hi Richard,<br> </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
1. Try skipping the v.category step. Try v.to.db option=cat column=cat<br></blockquote><div>I did, but it still doesn't work....<br>When I run v.to.db I get:<br><br>GRASS 6.4.0 (utm32):~ > v.to.db map=a_lidar_delaunay option=cat column=cat<br>
Reading features...<br> 100%<br>Updating database...<br> 100%<br>0 categories read from vector map (layer 1)<br>0 records updated/inserted (layer 1)<br><br>and the attribute table is still empty.<br> </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
2. What do you get from <a href="http://v.info" target="_blank">v.info</a> on the v.delaunay output?<br></blockquote><div><br>That's the output:<br><br><a href="http://v.info">v.info</a> a_lidar_delaunay<br> +----------------------------------------------------------------------------+<br>
| Layer: a_lidar_delaunay |<br> | Mapset: andre |<br> | Location: utm32 |<br>
| Database: /home/andrea/grassdata |<br> | Title: |<br> | Map scale: 1:1 |<br>
| Map format: native |<br> | Name of creator: andrea |<br> | Organization: |<br>
| Source date: Thu Mar 31 09:07:59 2011 |<br> |----------------------------------------------------------------------------|<br> | Type of Map: vector (level: 2) |<br>
| |<br> | Number of points: 0 Number of areas: 0 |<br> | Number of lines: 29971 Number of islands: 0 |<br>
| Number of boundaries: 0 Number of faces: 0 |<br> | Number of centroids: 0 Number of kernels: 0 |<br> | |<br>
| Map is 3D: No |<br> | Number of dblinks: 1 |<br> | |<br>
| Projection: Universal Transverse Mercator (zone 0) |<br> | N: 5150078.68 S: 5150000 |<br> | E: 1738099.33 W: 1738000.01 |<br>
| |<br> | Digitization threshold: 0 |<br> | Comments: |<br>
| |<br> +----------------------------------------------------------------------------+<br><br><br>If I run v.delaunay without the -l switch (and thus not obtaining the lines but the whole triangles), then v.category and v.to.db work,so I think that maybe there's some issue with the way v.delaunay generates the lines?<br>
<br>Cheers<br>Andrea<br> </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Cheers,<br><font color="#888888">
Richard<br>
<br>
</font></blockquote></div><br>