1. ## SubD Circles

Hi everyone and Merry almost Christmas,

I'm working in subpatch mode and I'm not sure how to get a circle out of a subpatched quad. I see a lot of great work with a subpatched quad being extruded to produce cylindrical objects that actually look round. I'm getting something close to round but it's obvious that the object isn't quite round. I read in a thread that subpatch has problems taking a cube and making it almost a sphere but not quite. How are you guys working around this to produce the great modeling I see in the forums? Thanks as always!

Richard

2. As far as I know you can't have it good enough with 4 sided. Try with an 8 sided at least.
It will never be a circle, it will just deceive you better.

Cheers

3. It'll be the first time I wouldn't mind being deceived... Thanks for the input!

Richard

4. OK, I see that I'll have to start with an eight sided disc and that will give me the rounded quads that holds up when rotated. Thanks again for the insight. Without the forum I would really be lost.

Richard

5. The information in this thread is worth bookmarking if you're doing a lot of subd modeling.

http://www.pixelandpoly.com/video.html

7. Originally Posted by Richard Hebert
OK, I see that I'll have to start with an eight sided disc and that will give me the rounded quads that holds up when rotated. Thanks again for the insight. Without the forum I would really be lost.

Richard
Have a look at the links in my sig. That will also help you sort out SubD work. Obviously you'll have to get past circles into more complex shapes. But you are on the right track by trying to understand the fundamentals first.

8. Yup... but doesnt have to be a disc you use to start.

Draw a perfect square (4 verts), subdivide, using metaform, hit tab. 4 quads, perfect circle.

9. @nickdigital
Were you going to put a link?

Originally Posted by RebelHill
Yup... but doesnt have to be a disc you use to start.

Draw a perfect square (4 verts), subdivide, using metaform, hit tab. 4 quads, perfect circle.
Well thats an 8 sided shape, and the way you are going it's not even close to a circle (doesn't result in a disc) and even when it is, it's not ''perfect'' it will always be an approximation. Only that the more cage point you have the closer to a circle will be.

Another issue with SubD circles is that they don't have the exact radius of the disc cage, they bulge in.
Here are some values you can size your cage into depending on the number of sides. But this of course, is just if such precision is needed. Normally it isn't.

10. Thanks Probiner,

While great precision isn't needed right now (I'm not doing CAD work) the info. helps me to understand what's to be expected and why. Thanks again.

11. I am hesitant to post in the presence of the experienced ones posting above. But I'd like to mention restraining loops. Attached is a model of a (for all but precise work) round circle and cylinder with 4 sides. As you can see the structure shape is controlled by loops placed close to either side of change of direction. It's used all the time in sub-d models as Probiner has used in his great illustrations. In the "low poly, close enough world" of sub-d modeling, use of these loops is crucial and felt it should be part of the discussion.

12. Originally Posted by probiner
@nickdigital
Were you going to put a link?
Oops!