Perfect Circle

Hey there,

How do I create an exact circular plane using subd?

Thanks in advance.

Hi Lewis -

You can’t. For exact circulars you need to use NURBS.

But if you use enough control points , you can get the deviation from a true circle to be so small, that even the center osnap will recognize it as a circle - here’s a triangle fan with 12 segments. Visually you will not be able to tell the deviation, but it’s there - in this case it’s 0.0105mm on a ø100mm circle.



Or at least I could have sworn that was the case, but it’s not. Sorry for the noise!

This is an example with Grasshopper, you can create subd shape closer to circle but it is not a perfect circle.

subd (12.5 KB)

it would be nice to have some info about the deviation for both

  • deformable arcs / circles
  • subD-Cylinders / spheres …

it would be nice to have the info in the commandline, after starting the command (for current values) or after changing the options
(deformable: degree, Number of CVs)
(sub-D “arround faces”)

for example I imagine entering Degree 5 and 10 CVs for a deformable circle in a document with 0.001 units tolerance, a feedback would be great: maximum diameter within document-tolerance: 500mm.
the inverse info or an adaptive CV-Count would be great as well…
(providing the minimum number of CVs / faces to stay within tolerance)

Hi Jakob - there is a setting for Center osnap locating centers of approximate circles - (Options > Modeling aids) that may effect what happens here, I have not tested on SubDs.


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Are there plans to add weights to subds?

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@oberbichler This would be excellent!