Export SVG missing topology

[stumcconnel]

Hi folks,

I'm generating some zero-thickness STL meshes using scripting in Blender and as far as I can tell, they're valid meshes and are consistent in terms of normal directions, etc.

I am then using MeshMixer to convert these STLs so that I can use them in PCB design and laser cutting. I don't have original CAD files for them, so I can't go the far simpler route of CAD direct to manufacturing formats.

For some topologies, it works fine, but for some there are missing features in the exported SVG files.

I have tried modifying my meshes in all manner of ways, from using tris, quads, ngons, beautifying tris, etc, and these variations usually result in different features being included or excluded, but I can't get anything to work 100%. The results are even sporadic on very simple STL files with only a handful of features, so I'm inclined to think I'm either using it incorrectly or not-as-intended, or I'm expecting too much from the SVG conversion.

I am using the default SVG export settings. I have not found I can improve anything by adjusting any of the settings.

Below are some example screenshots showing the issue. I have attached the STL of the simpler version.

Does anyone have any ideas? I can't find any other way to convert STL to SVG other than meshmixer, and it's so close I don't want to abandon it (not to mention several dozen hours invested into this workflow).

Cheers,

Stu

[Anonymous · Accepted solution]

SVG Export generates one separate n-polygon per boundary loop.

At default SVG export settings MM creates these polygons with an infill. In this case the resulting polygons ARE there but the order of the SVG layer stack may be "wrong" (a bigger polygon may hide a smaller one for the smaller one is below the bigger one). That may happen if your third party application reads the polygons plus its infill (not just the contours). That's why you can't see some interior polygons.

If you export a SVG from MM without an infill things should be fine (if the third party app doesn't do an infill automatically)

[stumcconnel]

That did the job. You're a life saver, thank you!