OBJ loading and export causing self-intersections

[kampelmuehler]

I do have an obj file representing the following geometry

when I load this obj file with trimesh and export it again directly the mesh will have defects. This is what Meshlab shows when I run "select self intersecting faces":

Those defects are also represented as entities in mesh.outline(). For the original mesh in Meshlab the selection remains empty.

If I first convert the obj to ply in Meshlab, then load and export in trimesh no such "self intersections" are created. I write "self intersections" because really they are not visibly self intersections.

What might be the issue here?

[mikedh]

Hey, is it possible this is from merging vertices? Does it happen with trimesh.load('thing.obj', process=False)?

[kampelmuehler]

Unfortunately this does not change behavior.

[mikedh]

Can you provide the before and after files?

[kampelmuehler]

sample.zip

Here's how I generated them (sample.obj is the original): trimesh.load('sample.obj', process=False).export('sample_no_process.obj') trimesh.load('sample.obj').export('sample_process.obj')

[mikedh]

Thanks for the models! I'm not sure what's going on here as this is a somewhat complicated interleaved file, but I did notice if you load with m = trimesh.load('sample.obj', process=False, maintain_order=True) it has a lot more vertices and renders more nicely.