3ds max: wavefront .obj export causes shading artifacts

Question

I'm trying to export a 3ds max scene to .obj format, unfortunately when I import the .obj file after having exported it using the default export settings the imported model has shading artifacts on a small part of the polygons (in particular of the front windows of the model shown in the images). As it turns out the original model had some open edges and these were causing the shading artifacts at .obj export time.

Please take a look at the following image: Example model with and without artifacts

After applying a vertex weld to the imported .obj mesh with a treshold of 0.0 the shading artifacts disappeared. However I'd like to prevent the shading artifacts all together (even when there are open edges present in the original mesh) since I cannot apply the afore mentioned vertex weld modifier after the .obj export has been performed without having to re-export.

The export settings used: export settings Note: checking/unchecking the "optimize:vertex" checkbox did not have an effect on the creation of the smoothing artifacts.

.max and .obj files of the example model: https://mega.nz/#F!CglwhYCD!UoG7cxPn5Rkmv-GC2H6cDA

Any suggestions on what I'm doing wrong/what is causing the problem/how to prevent it will be greatly appreciated. Thank you very much!

Answer 1

There are overlapping polys and vertices on that whole part. It is not one sided, there are polys on the other side of the surface too and the thickness is 0. This is the cause. You can see it if you select a vertex and delete it, there is another just on the same spot. Welding is probably not a good idea, you should simply delete the back side.