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View Full Version : "Pinching" subpatches



FenrirWolf
05-01-2003, 01:39 AM
Okay, I know this is gotta be a really stupid question for some of you more advanced modelers, but here's something that happens on occasion that just drives me bonkers. When I'm working with subpatches, I occasionally get "pinches" or visible seams.

Now, I know that if polys edges don't match up (like a 3-poly abrutting a 4-poly) will cause this effect, but my subpatch cage looks OK. Am I stretching them too much?

In layout, it can either not be noticable (if I crank the subdiv at around 9 or so), or very noticable.

Here's what my subpatch looks like in modeler with smooth shading:

http://www.gapingwolf.com/subpatch1.png

And here's my mesh:

http://www.gapingwolf.com/subpatch2.png

Someone who has more experience than me want to clue me in? :)

TerryFord
05-01-2003, 04:11 AM
Does it show in a render? If not just ignore it. A lot of artifacts like these are only visable in the OpenGL previews.

Regards,
Terry

TyVole
05-01-2003, 06:16 AM
This happens when five quadrangles meet at a single point. I believe the problem is that LightWave doesn't implement true SubDs. When I load the same model into Blender, I never get the creases.

As a solution, you can either use the Spin Quads command (although I find it hard to know which quads to spin); or better yet, rework your geometry.

FenrirWolf
05-01-2003, 11:56 AM
TerryFord, sometimes it shows up -- like I mentioned, if I bump the subdivision level of the object up to pretty high, like around 9 or so, these pinches will sometimes disappear.

Okay, TyVole, I guess that means that I will have to keep that in mind when working with SubD geometry. I will try the spin quads, but as you said, you can't just select them all and spin away, have to figure out which ones first.