Subsample a point cloud along the X&Y axis only

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EMPWILKO
Posts: 1
Joined: Tue Jun 08, 2021 8:38 am

Subsample a point cloud along the X&Y axis only

Post by EMPWILKO »

I'm currently trying to understand the best workflow to make full use of a point cloud into ArchiCAD for a currently project. Ive managed to separate the ground and off-ground points to enable me to use the ground points to form a mesh via an xyz txt file but I have the issue of too many points for ArchiCAD to import.

Ive used Subsample to reduce the number of point to 1m intervals but this looses all the detail of the height data. Does anybody know how to subsample at different scales? I'd like to subsample along the X and y axis only and maintain the Z height data detail.

If anyone has figured a workflow to achieve this and is happy to share I'd be greatful.

Thanks in advance!

DW
westergu
Posts: 25
Joined: Tue Oct 24, 2017 8:52 am

Re: Subsample a point cloud along the X&Y axis only

Post by westergu »

Hi,
If I understood your question right here follows one way how to do it:
1. Export the z coordinate values to a scalar field (Edit|Scalar field|Export coordinate to SF)
2. Flatten your point cloud via Edit|Multiply/scale and set scale (x) and (y) to 1 and scale (z) to 0
3. Run subsampling
4. Export the scalar field (z-value) back to the point cloud (Edit|Scalar fields|Set SF as coordinates.


Best regards, Gustav
redleg_64
Posts: 4
Joined: Sat May 29, 2021 2:23 pm

Re: Subsample a point cloud along the X&Y axis only

Post by redleg_64 »

westergu wrote: Wed Jun 09, 2021 8:05 am Hi,
If I understood your question right here follows one way how to do it:
1. Export the z coordinate values to a scalar field (Edit|Scalar field|Export coordinate to SF)
2. Flatten your point cloud via Edit|Multiply/scale and set scale (x) and (y) to 1 and scale (z) to 0
3. Run subsampling
4. Export the scalar field (z-value) back to the point cloud (Edit|Scalar fields|Set SF as coordinates.


Best regards, Gustav
This might help me also. Thanks!
daniel
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Location: Grenoble, France
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Re: Subsample a point cloud along the X&Y axis only

Post by daniel »

I would be surprised this helps since Subsampling works with the 3D distance between points (hence, making the cloud flat will just result in more points being removed?). Or did I misunderstood something?

Maybe the 'Rasterize' too can help?
Daniel, CloudCompare admin
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