Hi Paolo,

> You can find the fuut.3dm model file in message
> 2202.12 early in this thread

I examined your model and it all seems to be joined properly and in the polygon output I can't find any mismatching vertices.

I think that possibly the n-gon output is giving you the wrong idea about not having matching vertices here, let me illustrate this a bit.

Here is a view of the mesh output from MoI:



Zooming into the circled area above, let me focus on this polygon shaded in red here:



That polygon does not have the exact same UV "quad" structure as the surface adjacent to it, but that does not mean that it does not have shared points.

You will get an n-gon there that has points added to it to match every single point from the other surface, so for instance that polygon shaded in red is not actually a quad like you might think at first, it is actually a 5-point n-gon with points in it like so:



Note how point #4 was added so that there are shared vertices between all polygons.


If you switch to Output: Quads & Triangles this may become more clear, as you will see those n-gon polygons broken down into triangles:




Unfortunately, it is not very unusual for programs to have difficulty and various bugs when dealing with n-gon polygon data. That is likely to be what you are seeing in that area in Silo. when you see this problem the easiest solution is to switch the Output: option in MoI's exporter to Output: Quads & Triangles - this will use MoI's code to break the n-gon into only 3 or 4-sided polygons which will avoid n-gon processing bugs in your other program.

To verify the data, I took your fuut.3dm file converted with default options (with n-gons) into Cinema4D and did not see any problems there:




Also in Cinema4D I moved individual vertices around to verify that there were only single vertices as expected after using the "weld" export from MoI and could not find any duplicated vertices.

I also took the data into Rhino and used its CheckMesh tool which reported the mesh as solid which means there were all shared vertices in there as well.

So as best as I can tell the data exported from MoI has all single vertices like you wanted to get.

Generally when you see things like you saw in Silo it is an indication of an n-gon processing bug in the other application, you can report it to the other application's authors for them to fix, or you can switch to Output:Quads & Triangles when exporting from MoI to avoid using n-gons.

For 3D coat like I mentioned previously it is also a little different - not only does it not really want n-gons but I think it also wants to have more evenly sized polygons so you'll want to use the "divide larger than" option to dice up polygons into smaller bits at export time so that the mesh is formed better for displacement type use (that's in addition to using Output: Quads & Triangles). See some of those previous links for some examples of doing this kind of "evenly size dicing".

In general if you are seeing a lot of these problems I would suggest switching to Output:Quads & Triangles instead and probably they will all go away. If that is not the case please let me know.

Hope this helps,

- Michael