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Use 3D scan in Onshape

glib_kotelnytskyyglib_kotelnytskyy Member Posts: 20
edited January 27 in Community Support
there were number of posts on why Onshape is not the tool to use mesh, but I still want to incorporate it into my design, maybe you can suggest overall process, outside Onshape as well.
I have a slab of wood that I plan on using as a tabletop for a c-table. 
https://cad.onshape.com/documents/d00ceaba15e3ae5795e20cc8/w/548a53c2a46fec17f8000f18/e/5b289bdfe74c787a08ec07e3
The design is on “part studio 1”, and I’ve tried importing the scan .obj file into part studios derevyaha 2, derevyaha, mmd1, mmd1stl. The scan has over 2 million triangles, so I’ve tried reducing and converting to solid it in mesh mixer, converting to a solid in Resurf obj mesh to solid — all with no luck. It still appears as a surface in part studio, I cannot make it to interact with other parts.


I need to cut the scan with a plane to understand how to machine the slab, and have appropriate cutouts for the underside in the leg.
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Answers

  • billy2billy2 Member, OS Professional, Mentor, Developers Posts: 1,179 PRO
    edited January 27
    I use an obj format for my meshes. 

    shift-x: will section a model including the mesh
    edit appearance: and make the mesh transparent
    mesh folder: RMB and hide the mesh 

    Before importing to OS, I clean'm up using mesh lab removing bits I don't want. I do export obj out of mesh lab.

    OS is a boundary representation modeler and not a faceted modeler. You can't cut an OS part with a mesh. apples & oranges they're not the same thing.

    You can manually create a surface from the mesh, and then cut with the surface. You can create beautiful surfaces manually with the mesh being a guide. 

    If you're using another software converting a mesh to a surface, then you'll need to be importing: IGES, STEP or Parasolids into OS.

    Creating a surface from a mesh using software is not something I'd do. I want to use a well-formed surface and would prefer the constructs to build a surface  vs.  what a software's interpretation of the mesh would be. Having a node point at each polygon's vertex is insane and I'd hope they'd have some really good simplification algorithms minimizing the amount of data generated from a mesh to surface conversion. I'm a 2 noded spline type guy and I'm not interested in a surface that was created from a 1,000 nodes. Ain't going to be in my model and I don't have the patients to deal with that type of data. Remember, if you cut with that 1,000 noded surface and build a product with that surface, your original definition never goes away and will always be a problem.

    I seen over the years, many projects that have begun with scanned data. All will eventually fall apart from bloated geometry and there's no easy fix other than starting over with cleaner geometry.

    My point, there's no free lunch, if you're converting mesh data to a surface, make sure it's simplified, then simplified & lastly simplify it.

    If you need help bringing in a mesh and constructing a surface, then I can help.




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