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

Tue Mar 21 01:07:16 PDT 2023

Hi Saber,

It is a good point  - to use the source.

I think the source was a point cloud data set.

So, ideally, it could be a point cloud to mesh tool (or TIN).

I see that Alex Bruy just committed a point cloud to raster tool (going
through TIN is an option), but not as a final TIN result.

Andreas

On Tue, 21 Mar 2023 at 08:42, Saber Razmjooei via QGIS-Developer <
qgis-developer at lists.osgeo.org> wrote:

> Hi Andreas,
>
> Indeed, there is no native tool at the moment to convert raster directly
> to mesh. I filed a ticket with a link to this discussion so we can add it
> to QGIS later:
> https://github.com/qgis/QGIS/issues/52313
>
> But, in general, I would first try to find the source of the DEM raster
> (e.g. point cloud or spot survey) and use the raw data to create the mesh.
> This will avoid double interpolation :)
>
> Kind regards
> Saber
>
>
> On Mon, 20 Mar 2023 at 14:31, Andreas Neumann via QGIS-Developer <
> qgis-developer at lists.osgeo.org> wrote:
>
>> and there seems to be https://github.com/heremaps/tin-terrain
>>
>> However, I am looking for a solution integrated in QGIS ...
>>
>> On 2023-03-20 14:28, Andreas Neumann via QGIS-Developer wrote:
>>
>> 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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>>
>> --
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>
> --
> Saber Razmjooei
> www.lutraconsulting.co.uk
> +44 (0)7568 129733
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-- 

--
Andreas Neumann
QGIS.ORG board member (treasurer)
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