Rhino 8 Feature: ShrinkWrap

2 posts were merged into an existing topic: Rhino 8 shrinkwrap create wrong mesh

Awesome thread here!

Another use I just thought of > create self-intersecting geometry (which is a horrible pain to trim back) then use ShrinkWrap to ignore all of the messy internal stuff and generate a clean outer surface. A final Quad-Remesh would make it editable again.

Is this correct? I’ll make a demo file to test it.

yep- shrinkwrap, quadremesh, tosubd, tonurbs is the workflow to do what you are describing.

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Here is a very simple 3d mesh model to try “ShrinkWrap” on it just for fun. :slight_smile:

ShrinkWrap this model to find a bug in Rhino 8.3dm (97.6 KB)

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In this case it helps to offset the input mesh even if it creates self intersections. And subdivide a few times…

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ShrinkWrap will always wrap an object completely. Wrapping meshes or surfaces which have no volume means you get an infinitely thin wrapped volume, and thus holes where the infinite thinness collapses the wrap volume onto itself. As @martinsiegrist points out, you’ll need to offset the result in order for it not be infinitely thin and and look like swiss cheese.

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OK, nerds. I finished my successful test and posted the results in a new thread > Fun with Shrink Wrap & Quad ReMesh > Make a knot? Yup!

Wow. I would say that the Shrink Wrap command alone would be worth the upgrade to version 8. Weird but true.

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Actually, I posted this 3d model on purpose, because the bug is caused by a wrong interpretation of “ShrinkWrap” when the “Fill holes in input objects” option is active. Rhino considers the shape to be a hole, even though it’s pretty obvious that there is no such hole in the geometry.
Hopefully the tool will be improved in a way to give an option to choose the size of the “potential holes”, so that larger areas like this one will be excluded from the list of geometry to be wrapped/filled with straight mesh walls.

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What is your goal? As I mention shrinkwrap is not intended to work on single surfaces without volume as they are infinitely thin. The fill holes is calling Rhino’s FillMeshHoles. ShrinkWrap is not hole filling in a different manner.

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There is no hole to be filled in this particular 3d mesh model (a portion of the door panel of Ferrari LaFerrari), yet “ShrinkWrap” considers it a hole… This is clearly a bug or at least an obvious inability of the program to read the input geometry properly.

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Yes, that’s correct. The FillMeshHoles command is going to try to stitch all open edges of the mesh to close it up. This is what is happening, which is obviously not how the command is intended to be used. Run the FillMeshHoles command on your mesh. ShrinkWrap is made for working with objects that have a solid volume, not infinitely thin surfaces.

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yeah, but I think the command will be infinitely more useful if it can be relied on for fixing bad meshes from 3D scans, and spanning over terrible holes n’ stuff.

I made a thread on this a few months ago. I’m real happy with this new tool overall. I like where it’s heading.

Rhino is basically reverse engineering software, now. :smiling_face_with_tear:

Just need an alignment solution for scans. Although, meshlab is still on my list for study.

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Keep in mind that ShrinkWrap doesn’t “Fix”… it “Forgives”… :wink:

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Shrink wrap really wants an enclosed volume, as to achieve that, you can patch single face, or just jam an intersecting sphere or surface to patch over the holes.

see this video for ideas how to close up the “bad stuff” in meshes

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I noticed you helped me alot with my understanding of this command before :slightly_smiling_face:

This new command so awesome :star_struck:

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Hi, awesome tool, thank you

Just wondered, could this tool be applied from the inside out? That would allow to evaluate complex room volumes in buildings.

Thank you

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Post a file and a sketch of what you’d expect to see?

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This could be a great way to remodel negative space as well - for use in subtraction operations.

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not like you are thinking, I guess think of it this way… if you can seperate the surfaces that make up the room, shrinkwrap them and make a solid “chunk” out of just that room. you could then analyze the volume of that object or boolean it from another model.

does that make sense, or am I confused about what you are asking?

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Volume calc example.3dm (1.5 MB)
Hi, this is an example. When I use the shrink-wrap command, it calculates the volume from the outside in.
However, if instead of wrapping the shapes from the outside, the wrapping algorithm started from the inside, that would save us a lot of time. I hope it is clear.

There are many workarounds that we use to measure the volume, but using shrink-wrap would be such a convenient and fast method.

EDIT: in the example attached, I’d like to measure the volume inside the curvy shape, excluding the volume of the spheres and boxes.

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