How do I remove extra triangles from a mesh object?

Ultimately I want to be able to convert curved surfaces into flat planes and to unroll these flat planes so that I can plasma cut and weld the object in real life.

The way I know how to do this is by converting a NURBs object into a mesh. Then either “squish” it as a mesh or convert it back into a NURBs and “UnrollSrf” as seen in the short video I created for this post.

One of the problems I am having is once I convert the NURBs to mesh I have a superfluous amount of triangles on the top end of the cylinder. I want the top to be a polygon not a disjointed collection of triangles.

How do I do this?

Thank you!

Hi Joseph - if the object is made up of developable surfaces, like a cylinder, use UnrollSrf directly on the pre-mesh object - leave the meshing part out. Does that do what you need?


I only used a cylinder to illustrate a point. I want to scale this concept to complex models where I can take something like an organic model of a horse, convert it to flat planes (mesh), plasma cut those flat planes, and weld them together into a physical object.

In other words I need to unroll an object made up of flat planes.

Here are some more images illustrating what I want to do…

What you are missing is an option like known from the MoI3D meshing options (access per ini file only).
There you find CentroidTriangulation=y. I use it enabled always. Could be nice to get it for Rhino too.

How do I get and access “Mol3D” meshing options in Rhino?

No, not at Rhino yet, it was an example from the little brother of Rhino to second your request. I mean, we need this option for Rhino too and I would like to see it too.

If you need this kind of meshes for a project only than you could use the MoI3D demo.

I will have to look into Moi3D more.

But certainly there must be a way to modify meshes in Rhino? To create and delete edges?

If I need very low poly meshes in high quality than I use MoI3D always.

Here my best result from Rhino.

Thank you for the screen shot. I tried entering your details and this is the result I got:

Alright so I downloaded MoI3d. Perhaps you could help me achieve what I am looking for there.

Say I create a cylinder in MoI3d, how do I convert it to flat planes?

How about if I create a cylinder in MoI3d, how do I convert that to flat planes?


At Rhino - check the options at the lower end - is simple planes disabled? And the minimum initial grid quads 8 helped here.

At MoI3D - save as OBJ -> meshing UI will be opened. If your top surfaces doesn’t show the radial pattern than close MoI3D and open the ini file at the installation directory. Under meshing there should be the option CentroidTriangulation=y. Set it y (yes) …

Yes, I had it exactly as your details window had it, but did not get your results. Peculiar…

Saving as OBJ file via MOI3D was a helpful tip.

I cannot find the *ini file in the following directory though…

C:\Program Files (x86)\MoI 3.0 trial

Where is your ini file located specifically?

Thank you!

It should be at the installation directory. I don’t know why you don’t see it. You could try to place the attached ini to the directory.

PS: Sidenote - the MoI installation can be moved to any place you like, also to a USB stick.

moi.ini (5.6 KB)