What's up with polygon counting?

Rhino Rhino for Windows
1

I have a mesh that I need to export as 3ds, and thus have to keep it under the max polygon count limit (65536 (64k)) for 3ds for it to stay together as one part.

I then looked at the mesh properties it tells me that it has 51915 polygons, so all was fine…

So I exported and imported and to my surprice it came back in as two parts, so I selected the original mesh and typed ReduceMesh, but that showed a different meshcount:

Now what is causing that???

The mesh was generated in Rhino from a joined pipe structure, and the mesh is smooth and clean.
You can test this by simply making a curve, pipe it, mesh the pipe and check.

2

Hi Jørgen,

could it be the difference between quad count and triangulated quad count ? I´ve found that _PolygonCount also outputs triangulated count once used with a quad only mesh.

c.

3

Bump.

I just reducemeshed a mesh to 300.000 polygons, and if I rerun reducemesh then it shows that it hit 300K on the mark.
(I love that tool)

But if I open the object description (Object properties, Detail) then it tells me it has 277.013 polygons. Why are these numbers not the same?

Polygoncount also tells me it is 300.000.

4

Hi Jorgen- are there quads and triangles in the mesh? The 300 k total may include only triangles, that is, all quads split in two.

-Pascal

5

Hi Pascal,
I don’t think reduce mesh makes quads.
And this is a reduced mesh.

(so just make a mesh, reduce it and see for your self please)

6

Hi Jorgen- I did… make a mesh box, 10 by 10 by 10 and ReduceMesh from 1200 to 600 polys- then PolygonCount:

Command: PolygonCount
There are 186 quadrilateral polygons and 228 triangular polygons in this selection
There would be 600 total triangular polygons in this selection after forced triangulation

What says:

Valid mesh.
Closed polygon mesh: 387 vertices, 414 polygons with normals
  bounding box: (9.543,-2.829,0.000) to (21.824,14.293,12.248)

Does that correspond with what you’re seeing? My build is later than yours- I have no idea if there has been any change in this area…

-Pascal