Rhino Sketchup export triangulating surfaces

Unf even in Rhino, with lowest render mesh settings, when extracting a render mesh for a 6 sided box Rhino creates a mesh with 8 faces (top and bottom slit diagonally). Rhino image of extracted render mesh: image And the imported mesh in SKP is still triangulated all around: image I just retested the dwg export of similar box and got the correct result. The image of yellow box is from SKP with “view hidden geometry” enabled (no triangulation). Note, however, that to get this result, the dwg import dialogue in SKP must have “merge coplanar faces” checked (which is of course on the SKP side).

From SKP, dwg import from Rhino:

He @mwinkelstein
This has always been a limitation of the export to .skp from Rhino, and you are not the first one complaining about this. It’s been a long time since I exported something from Rhino to SketchUp but I used to use CleanUp extension in SketchUp to merge all coplanar faces automatically, maybe it worths a try.

Yes, please!

Edit: No, after thinking about it, the solution should be to merge coplanar faces and export as planar ngons. This is the only way you can assure edibility in SketchUp.

@jespizua - supposedly ‘Export planar regions as polygons’ should do this, I’d think… I confess I am slightly confused now as to what we are doing on export that is messing up in skp…


Hi @pascal, that is what I would expect from “ Export planar regions as polygons” but it has never worked properly, and I always relied on that CeanUp extension in order to further develop a file in SketchUp. The .skp import and export in Rhino is very limited and buggy and I already reported lots of issues long time ago in this https://discourse.mcneel.com/t/import-sketchup-file-bugs/51467topic and none of those had been solved… I would really appreciate if you could take a look.

Actually, ideally the merge coplanar faces should only happen for individual Rhino-triangulated surfaces, not, for example, entire fields of coplanar rectangular surfaces in Rhino. Otherwise you’ll end up in SKP with huge coplanar undifferentiated surfaces. Note that somehow SKP’s “merge coplanar faces” toggle in importing Rhino-created dwg files does this, i.e. two adjacent coplanar rectilinear surfaces in Rhino will come into SKP and remain as two different faces (without hidden triangular subdivision). So the SKP dwg merge coplanar faces button only merges the Rhino-triangulated rect faces back into their original form.

Also, the sketchup CleanUp sketchup extension is useful but has the problem that it tends to merge all coplanar adjacent faces into one big one and does not preserve the original differentiated rectangles. Most of the time what I am looking for is simply no triangular faces in sketchup, and also preservation of the original Rhino rectangular faces as individual rectangles (so they are useful in sketchup with editing tools like push/pull). Thanks.

Yes, I meant, merge coplanar faces for each original Rhino surface, this way the exported geometry will maintain the original boundaries.

Which in my understanding is the same as “ Export planar regions as polygons“ just to be clear

Today I worked a house-model in rhino 6, and I had the same big problem when exporting everything in Sketchup 2019…
, big problems for simple operations,
and vray couldn’t work well either, now I understand why! …
Sketchup had serious problems for simple operations…
if you know how to solve that, …
Please, Contact to know how to process !
Thanks & Greetings.
(Export to .collada file,…to obj.file ?..to skp.file).

I find the same problem,
But i dont know the answer.
(Exporting dwg to skp, but after that i need to put the materials,
With skp and vray).
Which are you best answer pls?

Until McNeel fixes the Rhino to Sketchup export regarding this issue, your best bet is to export dwg files from Rhino, import those to Sketchup and make sure to check “merge coplanar faces” when you import. This should solve the surface triangulation problem (but creates other issues).

Yes, unfortunately I believe you may lose the materials mapped in Rhino when you export to Sketchup with dwg.

Thank you !
(We —the users license—pay new versions,…Rhino…
but the simple problems stay always there).
I dont understand why?.

I’d like to understand the “Export planar regions as polygons“ problem. If you export a 3x3 (numbers are arbitrary, anything but 1) MeshPlane to SketchUp and have “Export planar regions as polygons“ checked do you see triangles with that file in SketchUp? If yes, what shading setting do you have set in SketchUp?


Yes - there is no way to avoid this. I have tried exporting meshes, surfaces, every possible setting, etc. (Examples and discussion farther up in this string I believe.) No matter what the settings, geometry imported to Sketchup from Rhino using Rhino’s Sketchup exporter will be triangulated. It will look great initially in Sketchup and retain material mapping, include loose curve lines, layers, etc. However, when you show hidden geometry in Sketchup you’ll see that each quad surface is triangulated. This is a deal breaker if you want to do any editing in Sketchup, as the push/pull extrude tool will not work on these triangulated quads. Additionally, it creates problems down the line if you want to export to Vray or run Vray on top. So basically the Rhino Sketchup exporter is near perfect in most ways but has a fatal unsolvable flaw. Please note that Sketchup has a button in its dwg import routine that enables you to solve this issue with incoming triangulated surface geometry if you export dwg geometry from Rhino, but you then run in to other issues with lost materials, etc. The Rhino Sketchup exporter problem constitutes a truly huge issue for those of us in offices working in both Rhino and Sketchup and needing constant efficient interoperability and geometry exchange

If I make a 10x10x10 mesh box and export to skp. I’m able to push and pull sides without any trouble. Here are 2 .skp files, try them for yourself. One was the standard “Export planar regions as polygons“ and the other I turned on an option that you see when you script .skp export called “CullUnnecessaryVertices”. It will remove unnecessary interior colinear boundary vertices. So in the case of a box instead of getting 40 vertices along a face border you get 4. If these work for you then I guess I need to see your simplest model that exhibits the behavior.


meshbox10x10x10.skp (15.7 KB) meshbox10x10x10.3dm (31.5 KB) meshbox10x10x10_culled_border_vertices.skp (8.4 KB)

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Hi @Tim,
It works with your example because you started from a mesh, but if you create a simple box using nurbs and you try it again, you will see the problem.
nurbs-meshbox10x10x10.3dm (3.1 MB) nurbs-meshbox10x10x10.skp (7.9 KB)

So, seems like something gets messed up at export time and export as export planar region as polygons is not been taken into consideration when working with nurbs geometry.

Thank you. That was very helpful. Sketchup uses the render meshes of objects so it can preserve the block hierarchy, it doesn’t make the meshes on export (doing that creates individual meshes that are in the transformed locations of the blocks). I was able to repeat what you said with a box and also by extracting the render mesh and exporting that alone. Now I have something I can look into.

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