[GRASS-user] rasterize 3d line

[Frank David]

Hi Vincent,

Yes it' works ! thank you for the trick

Regards,

Frank

Le 07/04/2023 à 13:37, Vincent Bain a écrit :
> Hi Franck,
>
> I would suggest you to do sth as follows :
>
> - if necessary add vertice along your 3d lines (v.split ?) so their
> "density" is roughly equivalent to (or better smaller than) your target
> raster resolution ;
> - turn your vector lines to points using v.to.points (with use=vertex
> argument) ;
> - convert this vector point map to a raster with v.to.rast (with use=z
> argument) ;
> - depending on what you do afterwards with that map, you can have a
> look at r.null to manage null raster cells (e.g. setnull=0).
>
> Hope this helps,
>
> V.
>
> Le vendredi 07 avril 2023 à 12:45 +0200, Frank David a écrit :
>> Hello,
>>
>> Thank you for your message. But I don't think it helps me.
>>
>> I want to add a bridge elevation to my DEM. So if I create a 3d
>> vector
>> line (my bridge) with two vertex at x,y,z coordinates, and is it
>> possible to convert in a raster where each cells crossed by the line
>> inherits of his extrapolated altitude ? If no module exists to do
>> that,
>> what would be the operations necessary to achieve this result ? I
>> hope
>> it is clearer.
>>
>> Frank
>>
>> Le 07/04/2023 à 10:16, Helmut Kudrnovsky a écrit :
>>>> Is there a way to rasterize a 3d line to get altitude on raster
>>>> cells
>>>> crossed by the line ?
>>> not quite sure what are you trying to do?
>>>
>>> maybe:
>>>
>>> v.drape:
>>>
>>> Converts 2D vector features to 3D by sampling of elevation raster
>>> map. (https://grass.osgeo.org/grass82/manuals/v.drape.html)
>>> Additional vertices can be added to the input 2D vector map with
>>> v.split.
>>>
>>> or the something like:
>>>
>>> v.fixed.segmentpoints - segment points along a vector line with
>>> fixed distances
>>> (https://grass.osgeo.org/grass82/manuals/addons/v.fixed.segmentpoints.html
>>> ) followed by
>>> v.what.rast - Uploads raster values at positions of vector points
>>> to the table
>>> (https://grass.osgeo.org/grass82/manuals/v.what.rast.html) or
>>> v.sample - Samples a raster map at vector point locations
>>> (https://grass.osgeo.org/grass82/manuals/v.sample.html).
>>>
>>>
>>> kind regards
>>> helmut
>>>
>>>
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