[GRASS-user] Re: How to extract z-coordiante and write it into attribute table?

Micha Silver micha at arava.co.il
Wed Mar 23 14:52:38 EDT 2011

On 03/23/2011 08:35 PM, TimNorwey wrote:

>> Your point cloud was imported in 3d vector mode but not yet connected to
>> an attribute table. Do this this way :
>> v.db.addtable map=lidar columns='cat integer,x double precision,y double
>> precision, z double precision'
> -->  worked fine
>> To that point a table is connected to your vector and necessary fields
>> were added to the table. So you can upload x,y,z values to the table :
>> v.to.db map=lidar type=point option=coor columns=x,y,z
> -->  Unfortunately, this executed with an error. Only in the first row of the
> attribute table the coordinates are added.
> It is said that there are 43 categories that have "more elements" and so the
> coordinates are not loaded (see below)

Could there be other extraneous values somewhere in the original ascii 
file? Maybe rows with an extra comma, or other characters? Can you make 
a bunch of rows available online somewhere so that we can have a look?

Another point you might want to take advantage of: v.in.ascii has an 
option (-z) to create a 3D vector. This means that each point's geometry 
consists of x,y, and z. So you then have the elevation available even if 
the values are not actually in the attribute table. For example, you can 
interpolate a dem from a 3D vector with no attribute table at all.

> http://osgeo-org.1803224.n2.nabble.com/file/n6201431/errorNew.png
> Thank you very much for your assistance!
> Tim
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Micha Silver
Arava Development Co. +972-52-3665918

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