[Updated on: Sun, 22 April 2012 21:51 UTC]

It is not that a single face is intersecting itself, but rather that the shell as a whole has faces that intersect each other.

Here is an extreme example: the red faces are self-intersecting with the green face.


Several drawing programs have trouble with this kind of geometry. With some programs you can apply a "boolean" operation to resolve some such cases, but the particular case I've shown here is very problematic.

Meshlab has an operation called "Alpha shape" but I've not succeeded in getting it to work in very many cases. I usually have to add my own extra vertexes to resolve the problem areas. This can be particularly troublesome if such faces are extremely small.

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[Updated on: Mon, 23 April 2012 05:31 UTC]

first of a picture of the problem:


What happens is that the geometry as to be 3d-plotted will come out fine. The white polygons however, which are on all sides of the design are supposed to be grey 'concrete' like the rest.

@ stop4stuff: I do not know. I think it is some face going through a number of other faces. the face itself however i cannot seem to select in order to delete.

@ stonysmith
regretfully my case of selfintersection is not so clear. I do not see the faces in 3d studio max that according to netfabb intersect.

@ SG Designs, I've downloaded a eval copy of Rhino, but when i rendered my model in Rhino my model was pretty messed up with regard to normals, even after checking and fixing my mesh.

I am getting the self-intersecting face after I export the model from Revit. I've used .dwg and .fbx exports from Revit, Both give the same issues with the polygons. So I don't get a boolean of loft, I get meshes from Revit.

currently I am uploading a model in which I have tried to boolean one of the problems away...

Thanks so much for the assistance of y'all!

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Thanks for the explaination Stony. The difference in teminology got me confuddled.

@BNengineer

It looks like your model is made up of shells that share geometry, correct? If so, slightly overlapping the shells may fix the issue.

I hope this image shows what I mean.



Paul

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@stonysmith, checked the .wrl in the notepad, regretfully, none of my faces have transparency.

So I tried @stop4stuff (Paul's) solution. This seems to fix the meshes, but at the same time it creates issues with the vertex normals.


So i've taken a blunt object to the model and basically removed the erroneous parts from the inventor model and replaced them with boxes in the right colour. The outside is now perfect, the errors are now on the inside of the model.


I'd like to thank you all for sharing thoughts and methods on how to fix my issues. I hope the inside will not become an issue and that a perfect outside is enough.

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