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PaulNewman
07-27-2004, 10:11 PM
Anyone know how to model a perfect (or close to perfect) sphere using subD's. Especially solutions with only 4 sided polygons are most welcome. Of course the big idea is to use as few as possible control cage polygons. I'm using Lightwave, but the principle should be the same in the other apps.

Hypersurf
07-27-2004, 11:58 PM
take a cube, smooth it? most simple i think..

PaulNewman
07-28-2004, 06:54 AM
I think not. At least not in Lightwave - not by a long shot.

StephanD
07-28-2004, 02:30 PM
I think not. At least not in Lightwave - not by a long shot.

Create cube,
Apply a Subpatch and freeze it,what's the problem?

PaulNewman
07-28-2004, 06:01 PM
Problem is that the resulting surface is not spherical :
http://www.cgtalk.com/attachment.php?attachmentid=57359&stc=1
A = tesselated sphere
B = subD cube

I was hoping to achieve "A" with subD's using 4 sided polygons. Any suggestions? Is it at all possible? Or am I missing something?

Rabid pitbull
07-28-2004, 08:04 PM
Make box, metaform a few times times, spherize once or twice, hit tab.

Works fine for me, mathmatically perfect?? Maybe not, but it should pass very well as a sphere.


Also if poly count is issue you can try adjusting subdivide point weights.

Good luck,
James

PaulNewman
07-28-2004, 08:14 PM
Thanks James. That's the solution I'm after!

I used : metaform + spherize + metaform + spherize and then TAB for subD. All quad poly's. Slight remnant of the cube's 8 corners. I'll work on it. This way I have a sphere which I can enhance for closeup shots by simply pushing up the subD level for the renderer.

Xtrude
07-28-2004, 08:33 PM
if you wish to check out your results just copy and paste screenshot into your 2d editor, and then create a cirle outline same size and place over the sphere shot and check out the differences... :)

PaulNewman
07-28-2004, 08:53 PM
Good idea. However sometimes you can only see the flaws while actively rotating in the 3D viewport, with the silhouette appearing round but the surface showing small inconsistencies.

Rabid pitbull
07-28-2004, 10:34 PM
Also turn specularity up to see imperfections. What is the reason this must be a sub-d object?

PaulNewman
07-29-2004, 08:15 AM
I'm testing various ways to represent a character's eyeballs in such a way that the level of detail for the render is globally adjustable by a subD level and not by higher detail object replacement (depending on shot requirements). In this way the character retains a lightweight poly mesh which speeds up interactive setup without the need for object replacement.

However, object replacement is not bad at all, especially if you write a script to automate it for you.

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