[QGIS-Developer] Tool to create Mesh from raster layer?

Andreas Neumann a.neumann at carto.net
Mon Mar 20 06:28:33 PDT 2023


Hi,

Yes - exporting the raster to xyz points or to contour lines are both 
workarounds.

It would be nice, if QGIS would gain a direct algorithm of creating a 
mesh from a DEM - as many DTMs are provided as raster. It seems like 
SAGA has a raster DTM to TIN algorithm ( 
https://saga-gis.sourceforge.io/saga_tool_doc/8.5.1/tin_tools_0.html ) - 
but SAGA is a bit complicated to use within QGIS and SAGA support within 
QGIS processing may disappear in the future. Perhaps we could port the 
SAGA algorithm to QGIS - or maybe an alternative algorithm?

My goal is to replace the raster DTM with a MESH for 3D display - with 
the ability to edit the MESH at important points. The builtin 
triangulation of the QGIS 3D viewer (where you can have a raster DTM as 
a terrain source) is sometimes doing weird things - I'd like to control 
that better - e.g. by introducing additional break lines or manually 
editing the Mesh.

Andreas

On 2023-03-20 14:20, Stefan Giese (WhereGroup) via QGIS-Developer wrote:

> Hi all,
> 
> I think it is not nessasary to go through Blender, just use theese two 
> algorithm:
> 
> * pixeltopoints
> * tinmeshcreation
> 
> Best regards
> 
> Stefan
> 
> Am 20.03.2023 um 14:11 schrieb Sebastian Gutwein via QGIS-Developer:
> The ridiculous work around I use is to go through Blender using the 
> BlenderGIS plugin. Import the raster into Blender as a new mesh > 
> Decimate the mesh > Export as a shapefile > Run TIN Mesh Creation in 
> QGIS.
> 
> On Mon, Mar 20, 2023 at 9:03 AM Saber Razmjooei via QGIS-Developer 
> <qgis-developer at lists.osgeo.org> wrote:
> Hi Andreas,
> 
> There should be a tool to convert vector to mesh (under Processing > 
> Mesh > TIN Mesh Creation). There will also be some new Processing tools 
> for handling point clouds. But I am not aware of any Raster > Mesh 
> tools.
> 
> Kind regards
> Saber
> 
> On Mon, 20 Mar 2023 at 13:56, Andreas Neumann via QGIS-Developer 
> <qgis-developer at lists.osgeo.org> wrote:
> 
> Hi QGIS devs,
> 
> Is there a tool available to create a Mesh (or TIN as a special mesh 
> variation) from a source raster layer containing terrain values?
> 
> I did not find one - but maybe I didn't look everywhere.
> 
> If not in QGIS - do you know an external Open Source tool that could do 
> that, while keeping real world coordinates?
> 
> Thanks,
> 
> Andreas _______________________________________________
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