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Old 12-01-2004, 06:36 AM   #1
colintheys
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yet another skin shader / head model

EDIT:
Latest version: Dec 14

Thread: http://www.cgtalk.com/showthread.php?t=191586

EDIT

Hello all,

I'm a student and relatively new to XSI. I imported an old head model I made in Realsoft and decided to have a go at shading it. I've really been loving the XSI workflow and decided to put up my progress so far for crits. Comments on the model or texture are more than welcome. This is my first foray into shading in XSI and it is far from finished!


I attached four rendered images from the viewport of the model under different lighting conditions.





Just looking at these pictures, I'm thinking:
1. The dark lighting turns up some really ugly bumpy highlights in inappropriate places.
2. It looks a bit 'waxy'. Any thoughts on how to correct this?
3. The eyes need a lot of work.
4. I really need to draw separate bump / specular maps.

Thanks,
-Colin
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Last edited by colintheys : 12-15-2004 at 09:16 AM. Reason: update
 
Old 12-01-2004, 07:05 AM   #2
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Quote:
Originally Posted by colintheys
Hello all,


Just looking at these pictures, I'm thinking:
1. The dark lighting turns up some really ugly bumpy highlights in inappropriate places.
2. It looks a bit 'waxy'. Any thoughts on how to correct this?
3. The eyes need a lot of work.
4. I really need to draw separate bump / specular maps.

Thanks,
-Colin
First of all, it looks really great, but as you have said it has a few problems.
It does look too waxy, a common problem when using SSS. Try reducing the diffusion value in the shader, so that the light does not penetrate so deep below the skin's surface. You may even want to control the diffusion value using a map, with higher values in fleshy region of the face (end of nose, cheecks etc.) and lower values on bonier areas such as the forehead. It may mean making lots of seperate maps, but it will be worth the extra work. I once read that for SSS to work well it should not stand out i.e. it works best when it is very subtle. Right now it is too strong in your work.
You will indeed have to draw a seperate bump and specular map. Sure they can be heavily modified versions of the same base map, but for the best realistic results, you'll have to put in the extra bit. Right now I see you're using the colour map as your bump. I would recommend you start from scratch and paint a greyscale bump map. You'll definitely appreciate the extra control and the results you'll get.


Looking forward to some updates, good luck!
 
Old 12-03-2004, 01:48 PM   #3
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Thanks for the comments! Here's an update:



I'm going to try to render some more previews later today without the hair (because that really slows things down). Then I can get different angles and different lighting. The above image is 3-pt lighting with two area spots in front and one normal spot in back. The skin shader is almost completely re-worked.



I painted a new map for the intensity of the SSS and that looks a lot better in low-light. (I tried diffusion, but found that intensity have results more like what I was looking for.) A lot of my problems, though, come from the node labeled Frontal_Highlights. I just can't get them to look right. The model is looking a little plastic now, especially in the bridge of the nose zone. This node makes ugly highlights there. In the last version, that node was responsible for the ugly bumpy highlights on the face too. Don't quite know how to deal with those highlights properly. Maybe I need to make them a phong and not a blinn?

I still haven't painted a bump map and I think that's the next step? My only problem is that I don't know what to bump!! I've never painted a bump map for a face before, so it's going to be quite the trial and error experiment. Maybe some wrinkes... some overall bumpiness...

I decided to throw in some eyebrows too and went a little overboard... I put hair on his head, eyelashes, etc... hehe. It takes a long time to render 50,000 hairs with area lighting!

Thanks!
-Colin
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Old 12-03-2004, 03:37 PM   #4
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Hey, looking good. That hair is XSI hair? Looks pretty decent.
 
Old 12-03-2004, 03:43 PM   #5
colintheys
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Hi,


I figure this forum is probably not the best place for this thread (I should have thought of this before... but hey) so I started a new thread over in the wip:critique forum.

http://www.cgtalk.com/showthread.php?t=191586

Thanks!
-Colin
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Old 01-20-2006, 02:00 AM   #6
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