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[Other] Terrain point cloud to watertight surface

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Old   March 13, 2017, 07:32
Question Terrain point cloud to watertight surface
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Hi all,

is someone here working with terrain point clouds and preparing them for meshing with snappyHexMesh or cfMesh?

I am trying to figure out the best workflow in developing watertight surfaces ready for CFD simulation. Ofcourse when you have terrain data you have to be able to add boundaries above the terrain to close your model.

It is really about being able to import the point cloud into CAD software as a point cloud or in another format.

The best thing, as far as I know, is to create NURBS from your point cloud and work with that in the 3D design software. That would be much more lightweight than going for STL surfaces or similar.

All comments appreciated.
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Old   March 15, 2017, 08:49
Default Point cloud to the watertight surface mesh
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Franjo Juretic
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Hello,

Neither snappyHexMesh nor cfMesh require a watertight surface to perform volume meshing. cfMesh requies a domain to look closed such that it can distinguish between the outside and the volume than shall be filled with cells.

Have you ever considered using PCL library (http://pointclouds.org) or MeshLabl (http://www.meshlab.net/) to generate a triangulated surface from a point cloud?

To close the domain you can generate a cylinder surface mesh or a box surface mesh, merge it with the terrain mesh, and remove the face below the terrain. That is enough for meshing with cfMesh.
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Old   March 27, 2017, 11:38
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Thank you Franjo for your answer. My domain has irregular outside border and I was able to extract that out of the model. Then I could copy it to a distance above the original border and loft a surface between those profiles. Then I filled the top border with a flat surface. I came to these cocnlusing using your idea.

Thank you.

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Old   March 28, 2017, 11:12
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Quote:
Originally Posted by franjo_j View Post
Hello,

To close the domain you can generate a cylinder surface mesh or a box surface mesh, merge it with the terrain mesh, and remove the face below the terrain. That is enough for meshing with cfMesh.
Hi Franjo,

Which program do you recommend to close the domain?

Paulo
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