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TheDAve
12-06-2006, 01:11 PM
Can anyone help me with a problem I'm getting using Catmull-Clark SD's.
I'm working on a cartoon head (my most advanced organic model yet) using LW 9.0

http://www.digitaljoat.com/Temp/SDProblem/~00.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/00.jpg)

But when I render (using F9) I get a seam around the mouth (it's more noticable on the larger image)
http://www.digitaljoat.com/Temp/SDProblem/~01.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/01.jpg)

Then when I apply a endomorph using morph mapper (this is 50% of my smile endomorph) the seam is really apparent.
http://www.digitaljoat.com/Temp/SDProblem/~02.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/02.jpg)

The problem also shows up in layout
http://www.digitaljoat.com/Temp/SDProblem/~03.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/03.jpg)

While trying to determine the problem I turned on "Unshared Edges" in the object properties...
http://www.digitaljoat.com/Temp/SDProblem/~04.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/04.jpg)

and saw the problem area was highlighted
http://www.digitaljoat.com/Temp/SDProblem/~05.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/05.jpg)

But the edges all appear joined, and there are no 2 point polys or anything else wrong that I can see.

Swiching back to subdivision surfaces fixed the problem, but do not look half as nice.
http://www.digitaljoat.com/Temp/SDProblem/~06.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/06.jpg)


Particually when the character smiles.
http://www.digitaljoat.com/Temp/SDProblem/~07.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/07.jpg)

I tried using FPrime and get the same problem

http://www.digitaljoat.com/Temp/SDProblem/~08.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/08.jpg)

One thing I can see is that the corners of the mouth share with 5 polys and not 4...
http://www.digitaljoat.com/Temp/SDProblem/~09.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/09.jpg)
Is this a problem? If so any idea how I can fix this?

Does anyone have any other ideas for a fix/workaround?

Cheers for any help.

DAve

UnCommonGrafx
12-06-2006, 01:44 PM
It's been there since cc inception. Good luck on finding a fix as I don't think anyone has come up with one.

TheDAve
12-07-2006, 01:02 PM
So the problem is due to the point shared by 5 polys?

How do people get around this then?
As far as I can see wherever a loop of polys is used (i.e. around the mouth) at some point you are going to need/want a point shared by more than 5 polys to shape the rest of the head.

Or am I missing something?

DAve

UnCommonGrafx
12-07-2006, 01:13 PM
Sadly for your purposes, I think the workaround has been to go back to regular subpatches.

:(

TheDAve
12-07-2006, 04:30 PM
I just KNew you were going to say that :(

DAve

Celshader
12-07-2006, 04:44 PM
Does anyone have any other ideas for a fix/workaround?

Cheers for any help.

DAve

Please check one thing -- do you have Subdivision Order set to First or Last?

Endomorph-controlled Catmull-Clarks tear on my machine when I have SubD Order set to First, but not when set to "After Morphing" or higher.

UnCommonGrafx
12-07-2006, 05:05 PM
Save the day, Jen.
;)

TheDAve
12-13-2006, 06:25 AM
Please check one thing -- do you have Subdivision Order set to First or Last?

Endomorph-controlled Catmull-Clarks tear on my machine when I have SubD Order set to First, but not when set to "After Morphing" or higher.

Fantastic - I'll try that out (my day job has been keeping me busy this week - but I was going to take another look at this tonite. I'm glad I popped by)

DAve

Sensei
12-13-2006, 10:44 AM
There is big chance that you have some points not welded..
Problem with calculating normal vector shading is also visible in areas that in theory doesn't have 5 point polygons as visible on this image:
http://www.digitaljoat.com/Temp/SDProblem/02.jpg

Can you share object/head with us?

CAClark
12-13-2006, 10:53 AM
I've seem this even in the opengl of modeller.... enough for me to conclude that presently CC's are not very useful.

Cheers!

TheDAve
12-13-2006, 04:43 PM
Well,

I tried changing the Subdivision Order to last and this fixed the tearing (cheers Celshader).

http://www.digitaljoat.com/Temp/SDProblem/~11.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/11.jpg)

http://www.digitaljoat.com/Temp/SDProblem/~12.jpg
Larger Image (http://www.digitaljoat.com/Temp/SDProblem/12.jpg)

However, looking at the larger images there is still an obvious difference in the polys around the mouth.

I can't find any unwelded points Sensei, but you are welcome to look.

ElfHead.lwo (http://www.digitaljoat.com/Temp/SDProblem/ElfHead.lwo)

Thank you to everyone for their help.

DAve

Sensei
12-13-2006, 05:10 PM
Hi! I have "error reading object file" message from LW.. Please pack it to ZIP..

TheDAve
12-13-2006, 05:18 PM
Dang.... you are quick :)

I'd noticed the problem and was trying to get it fixed, but you beat me to it!

Try this...

ElfHead.zip (http://www.digitaljoat.com/Temp/SDProblem/ElfHead.zip)

DAve