[Qgis-user] Extract 3d attribute information

[Lens Paul]

Hi, Christof!

I didn't practice 3D for a while and I'm not a geek either.

QGIS does not explicitely treat vectorial 3D information, but some 
(many?) tools treat the vectors without losing Z values.
Besides, QGIS evolves so fast that it is difficult to keep track of the 
way it handles z information.

If I remember rightly (probably QGIS 2.x at that time), for those 3D 
compatible tools,  lines are not treated on a per vertex basis but with 
one z value for the whole line, keeping just the z value of one of the 
vertices I suppose.

  To get the mean value for  line made of vertices with different z 
values, I would try  this :
- decomposing (in Grass I suppose) the line in points with the z value  
in one attribute field and a line identifier in another field;
- calculating the mean z value in association with the line identifier;
- recomposing the line with the help of the line identifier.


Hope this helps,

Paul

Le 27/05/2015 16:19, Christof Kammerer a écrit :
>
> Hi!
>
> I have a 3d shp-file containing building outlines. What I need is an 
> attribute field with the value of the average altitude of the outline 
> of every single building.
>
> Is that possible with qgis/grass gis plugin? If not which other tools 
> exist to get this result?
>
>
> Sincerely, Christof
>
>
>
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