What's up with polygon counting?


#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.


(Pascal Golay) #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)


(Pascal Golay) #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