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I am creating multipatches from existing geometries and finding it hard to work out why IsClosed3D shows some as closed while other apparently closed geometries are shown as not closed.

I have worked out that the ordering of the vertices in different faces has an impact and also that the RingType can affect the result.

If I order all the vertices on the attached geometries to be clockwise, they are both not closed. If I change the order of the vertices one is closed and the other is not closed.

Any insights would be gratly appreciated.

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It's rather hard to visualize your the shapes/solids you're trying to do. I think a screenshot would give people a better idea as to why you're having that situation. – R.K. Sep 19 '12 at 4:28

1 Answer

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According to the ArcGIS Resource Center the tool:

Tests each multipatch to see if it completely encloses a volume. Then adds a new field with a flag for each multipatch feature in the input layer or feature class indicating if that feature is closed or not.

It could be that changing the order of the vertices closes the volume while others don't and they end up being just surfaces.

I think it would be easier to create your 3D models in Sketchup. The controls are easier then. Once you're done, you can then import the models to ArcGIS.

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The geometries are created in code - so Sketchup is not an option. – Alan Keown Sep 19 '12 at 19:50
The geometries are simple cubes with faces made from merged Triangles as Rings and individual triangles as Rings; the reordering doesn't change the values of the coordinates just if they are added clockwise or counter-clockwise. – Alan Keown Sep 19 '12 at 19:55
It seems that the tool expects a certain sequence of geometries in the multipatch, but I can't find any indication of what that is. – Alan Keown Sep 19 '12 at 19:58

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