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Question

Filter Point Cloud above/below a TIN surface


mgg_beca
Contributor
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Hi there,

 

If I have been given a TIN and a point cloud, how can I find out which points are above the surface and which are below, without rasterizing the surface to retain maximum surface fidelity.

Thanks,

Marc

3 replies

daveatsafe
Safer
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  • Safer
  • January 22, 2024

Hi @mgg_beca​,

I think the simplest process would be to use an Extruder to extrude the TIN by a distance that will encompass the highest point in the point cloud. Then use a Clipper to clip the point cloud by the extruded TIN. Inside points will be above, while Outside points will be below.

If the TIN is a mesh geometry, you may need to use a GeometryCoercer to convert to a composite surface before extruding.


mgg_beca
Contributor
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  • Author
  • Contributor
  • January 22, 2024
daveatsafe wrote:

Hi @mgg_beca​,

I think the simplest process would be to use an Extruder to extrude the TIN by a distance that will encompass the highest point in the point cloud. Then use a Clipper to clip the point cloud by the extruded TIN. Inside points will be above, while Outside points will be below.

If the TIN is a mesh geometry, you may need to use a GeometryCoercer to convert to a composite surface before extruding.

Hi @daveatsafe​ ,

 

I thought that might be the case, but figured I'd reach out and see if there was a more specific solution. I think there is definitely scope for a transformer to do this.

Regards,

Marc


james_c_452
Supporter
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  • Supporter
  • April 15, 2024

I think I’ve done something similar in the past. I think I copied the z value to a new component (Zorig). Then ran through the surface draper. Then I took a difference of the old z and the new z. If its negative is below ground, positive above ground


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