Meshing rules of SubD

SubDs in Rhino may be meshed in three different methods for rendering, viewport display, surface analysis, and mesh conversion. The three meshing methods are static, adaptive, and absolute.

Static meshing

How many mesh quads are created per SubD quad is based on the face count of the SubD.

Face count

Per SubD

1-2000

2001-8000

8001-32K

>32K

Mesh quads
per SubD quad

16x16

8x8

4x4

2x2

Static meshing cannot be configured and previewed.
Render meshes of SubDs in shaded viewports (Shaded, Rendered, Ghosted, and Xray display modes) ALWAYS use static meshing.
Render meshes of SubDs in the Raytraced viewports and final renderings use static meshing when Jagged and faster or Smooth and slower is selected in Document Properties > Mesh.
Static meshing reduces the render mesh faces of dense SubDs to increase display performance.

Adaptive meshing

How many mesh quads are created per SubD quad is based on the face count of the SubD and the Density or Level sliders in meshing dialog boxes.

Detailed Level	Simple Density	1-500 SubD faces	501-2000 SubD faces	2001-8000 SubD faces	8001-32K SubD faces	>32K SubD faces
1	0%	2x2	2x2	2x2	2x2	2x2
2	1-19%	4x4	4x4	4x4	4x4
3	20-34%	8x8	8x8	8x8
4	35-75%	16x16	16x16
5	76-100%	32x32	16x16

Render meshes of SubDs in the Raytraced viewports and final renderings use adaptive meshing when Custom is selected in Document Properties > Mesh.
Surface analysis commands always use adaptive meshing.
The slider of simple controls in the Mesh command uses adaptive meshing.
Adaptive meshing reduces the faces of render meshes and mesh conversion of dense SubDs with controls.

Absolute meshing

How many mesh quads are created per SubD quad is based on the Level slider. No other factor is involved.

Level	Mesh quads per SubD quad
1	2x2
2	4x4
3	8x8
4	16x16
5	32x32

Only the Level slider of the detailed controls in the Mesh command uses absolute meshing. All the rest in Rhino use either Static meshing or Adaptive meshing.
A high absolute meshing level may create too many mesh faces from dense SubDs and cause the system to run out of memory.

Reference table

This table shows where in Rhino the three meshing methods are used.

			Static meshing	Adaptive meshing	Absolute meshing	Use
Document Properties > Mesh	Jagged and faster		✔
	Smooth and slower		✔
	Custom	Simple > Density		✔
		Detailed > Level		✔
Object Properties > Custom mesh	Simple > Density			✔
	Detailed > Level			✔
Surface analysis commands > Adjust mesh	Simple > Density			✔
	Detailed > Level			✔
Mesh command / export	Simple > Density			✔
	Detailed > Level				✔

= For shaded viewports (Shaded, Rendered, Ghosted, and Xray modes)

= For the Raytraced viewport and final rendering

= For surface analysis

= For mesh conversion