Hi Michael,

I have a friend who's a very skilled Rhino user & at my suggestion has recently been trying out MoI.

One of his various tests was to create a surface in Rhino & see how well it would look once in MoI.
This surface was created in Rhino by using a simple surface that was rebuilt to 30 x 30 Points.
Then by taking every 4th Point selected & lifting it directly up.

The resulting display in Rhino needs to have the surface rebuilt by changing the Render Mesh settings to Smooth & Slower.
He then wondered if this same surface would also have the same kind of display problems when it was opened in MoI?
Unfortunately it did & so he asked me "any idea why?...and how can you change the Render Mesh settings like he can in Rhino?"

So thought I'd be just best to post it to the Forum for you to take a look at.

regards Colin

Hi Colin, the problem is that is a kind of unusual surface - your friend did not build it as a smooth surface, instead it is a single large degree 1 surface which means that even though it is a single surface it has a lot of sharp internal creases in it. Degree = 1 means that there is a straight line between each control point of the surface rather than there being a smooth curve between control points which is the more typical Degree = 3 case.

In normal usage, only a simple plane surface will have degree = 1.

MoI will take surfaces with internal creases like that and split them up, and the problem in this case appears to be in that splitting process, something involving the trimming boundaries is not getting split up properly, resulting in some pieces with an invalid trimming boundary. Invalid trimming boundaries can cause these kinds of meshing artifacts.

If he can get it to be split up in Rhino first and then export that to MoI it will probably solve the problem. One way to do that would be in Rhino run the ConvertToBeziers command on this surface, and then select all the little fragments and run Join on those to form a joined polysurface object rather than a "single surface with internal creases" type object.

Once you have it as a polysurface then bringing that into MoI will likely not have any issues.

The initial meshing problem in Rhino could also be related to this particular unusual surface construction of having a degree 1 surface with many points in it, making a creased surface.

Hope this helps,

- Michael

Hi Colin, also just in case I didn't answer the exact question:


> and how can you change the Render Mesh settings like he can in Rhino?"

The problem in MoI is actually a surface-splitting problem and not a render-meshing problem. The render mesh only looks weird because the surface crease splitter did not produce proper output from the creased degree 1 surface.

If you can get this surface split up before you bring it into MoI then it should show with a proper render mesh.

- Michael

Hi Michael,

It may be that I not getting this, when I bring this into MoI I'm getting the same thing that Colin shows and what I did was separate the joined surface and selected one of the repeated pockets which has nine smaller surfaces and deleted the the rest with the offending surfaces, then re-arrayed and joined everything back again.
Is this the same thing ?

Cheers
Danny

In Rhino- when pulling points, the render mesh does not update on the fly. You can force an update using the command RefreshShade. Also you can split creases in Rhino using the command DivideAlongCreases. Then copy/paste to Moi will have no issues...

Hi Danny, yeah that's another way to fix it - because it's a repeating pattern you can just throw out the bad pieces and copy some of the good parts over.

But I just wanted to describe what was going wrong with it - those bad pieces are getting created because of the original surface being a large surface that has internal creases in it, and it seems to be running into a bug in the surface splitter.

- Michael

OK, understood. Thanks for the clarification

-

Hi Michael,

Thanks for those explanations, I'll let my friend know.

regards Colin