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rsdemon
05-28-2007, 07:30 AM
Can anybody recommend a tutorial on the Skin/SSS shading in 9.2?

Ron

oDDity
05-28-2007, 07:46 AM
I've yet to see any realistic skin render come out of 9.x sss nodes, so don't get your hopes up.

kfinla
05-28-2007, 08:09 AM
I think the Don Knotts thread in the 9.2 gallery is the best example with some explaination so far. Hope that helps.

sammael
05-28-2007, 08:20 AM
I've yet to see any realistic skin render come out of 9.x sss nodes, so don't get your hopes up.
Its still early days I think we will see some good examples yet, all of the tools are there.

daug
05-28-2007, 08:32 AM
Ron didn't ask whether 9.2 SSS was any good, he asked for resources and tutorials...

jasonwestmas
05-28-2007, 08:37 AM
No there aren't any good tutorials on it. Just a ton of information scattered all about on this forum. (Just like most of the information on how to use lightwave). Seriously someone at newtek needs to help out in that area more, they'd get way more support from the community. But in the mean time I'll try to do my part as well.

rsdemon
05-28-2007, 08:39 AM
Ok. Is there any basic documentation on the Simple Skin node?

jameswillmott
05-28-2007, 08:52 AM
http://www.lightwiki.com/Skin

It's a very basic start, but the material is so geometry and lighting independant it's hard to make a tute that suits more than one object. Just play and see. Hopefully the link explains a few things.

People complain that there is so much information about how to use LW scattered around the forums, yet no one takes the time to add their little bit of knowledge to the wiki...

jasonwestmas
05-28-2007, 09:22 AM
Here's a node setup with a backlight and a foreground light. The red glow in the ear changes according to where the light and shadow is, that's one of the cooler features of SSS which works best with the simple skin material through the subdermal layer color. I think the SSS colors work best if there is good warm and cool contrast otherwise the colors will look too flat IMO. Also notice that there are color, spec and bump maps that contribute to the effect a great deal.

jasonwestmas
05-28-2007, 09:26 AM
http://www.thegnomonworkshop.com/tutorials.html

Also take a look at the mental ray fast skin shader tutorial. It's a little bit similar in process and will help in getting the colors to work together properly.

jasonwestmas
05-28-2007, 09:31 AM
Hey James,

Is there a way to use the same image for three separate nodes but be able to change the RGB values separately?? That would save on Ram.

jameswillmott
05-28-2007, 09:42 AM
Yes, you can use the Color Tool to fiddle the output of an Image node, changing hue saturation, brightness and contrast, just feed the one image node into three separate Color Tool nodes. You can also feed an Image node into three Gradient nodes and remap the colours separately.

jasonwestmas
05-28-2007, 09:43 AM
great, I'll give it a shot! Thanks James.

IMI
05-28-2007, 11:40 AM
I was beginning to think that I'm the only one who doesn't understand how the SSS shaders work.
Thanks for the info. :)

Nicolas Jordan
05-28-2007, 12:20 PM
I have seen quite a few renders where SSS is overdone. It always seems like when a new technology comes out most users crank it up to the extreme kinda like back in the days when everyone was making highly reflective balls except now it highly translucent surfaces. I have also seen some renders that are getting closer to the real thing but for the most part they are way overdone with translucency.

pooby
05-28-2007, 01:26 PM
http://www.lamrug.org/resources/doc/sss-skin-tutorial.pdf

this is for Mental ray, but its the same basic theory behind Lw's shader. I learnt from it.
In fact I learnt the mental ray shader first and I consider LW's to be much better but maybe that was because I improved.

Some tips.

The sub, Epi and Diff layers all having a percentage is misleading. It's just an additive effect. Do each one separately when gauging the depth of the SSS.

Specular is NOT specular. Its reflection, and glossiness is the amount of reflection blur

The main thing is that the head needs something to reflect. I would recommend using luminous polys with image maps on rather than a HDR sphere , just because it's a lot more controllable.

Also, it looks better if the whole head is lit by those polys, but it will take a huge amount of time to render. And also, it's extremely hard to get good contrast with this method. (due to ray sampling issues)

The Best method overall is to do a pass with no Specular (reflection) and use area lights.. ALL other lights look rubbish. Then do another specular pass for comping. Not only does this give you tons of control afterwards, it's far far quicker to do these 2 passes than try it all in one.

I may do a tutorial some time.

Cageman
05-28-2007, 02:38 PM
I've yet to see any realistic skin render come out of 9.x sss nodes, so don't get your hopes up.

Hmm... I don't doubt that one can achive really good SSS with LW9.2, but I wonder who has the computing power to do it? I certanly don't, and I've given up on the SSS-solutions that LW currently has built in. Until NT figures something out that can render on par with miSSS shaders (time vs quality), I'm not going to use LW for those things.

jasonwestmas
05-28-2007, 04:11 PM
Hmm... I don't doubt that one can achive really good SSS with LW9.2, but I wonder who has the computing power to do it? I certanly don't, and I've given up on the SSS-solutions that LW currently has built in. Until NT figures something out that can render on par with miSSS shaders (time vs quality), I'm not going to use LW for those things.

SSS in lightwave is no more time consuming than the boatload of other cool features that NT added to 9.2. It's all a matter of how much time you have and the quality of your settings. Of course anything photoreal is going to take longer to render in lightwave compared to mental ray. well a lot of things will be quicker with mental ray, not everything.

kfinla
05-28-2007, 08:02 PM
Thanks for the SSS tut Pooby, very handy, I'm enjoying the read now.

Cageman
05-28-2007, 08:48 PM
SSS in lightwave is no more time consuming than the boatload of other cool features that NT added to 9.2.

Uhhm... I'm not sure about that. I was able to render this (http://www.newtek.com/forums/showthread.php?t=65714) scene in 8m 33s. Not very fast compared to modern hardware, but way faster than anything I've tried using the SSS-nodes.

EDIT: BTW... when it comes to hard surface objects, LW seems to do a better job than MR, at least if you are going to belive the guys over at Zoic.

jasonwestmas
05-28-2007, 11:08 PM
Well I was kurious and just did a 20 hour render using 3 passes of photoreal motion blur on some long sasquatch hair guides. It looks pretty nice and fairly real. The blur hides all the noise in the sasquatch hair ;)

rso
09-20-2007, 02:14 AM
Hi Jason,

Thank you very much for your clearifying nodes setup on SSS and the simple skin material.


Here's a node setup with a backlight and a foreground light. The red glow in the ear changes according to where the light and shadow is, that's one of the cooler features of SSS which works best with the simple skin material through the subdermal layer color. I think the SSS colors work best if there is good warm and cool contrast otherwise the colors will look too flat IMO. Also notice that there are color, spec and bump maps that contribute to the effect a great deal.

It is still quite unclear to me what kind of textures should go into the Epidermis Color and Subdermis Color slot. Could you please further clearify this a bit to us. From what I have looked up about epidermis and subdermis e.g. in wikipedia, it seems that maybe some pigmented mole info or the hair roots etc. should be seen in an epidermis texture. The subdermis or rather "subcutis" is ought to contain blodd-vessels etc.

So is that understanding correct and are you using texture maps with such specific information contained or what colouring information would you suggest for each of the two slots?

Thank you in advance,

Robert

jasonwestmas
09-20-2007, 08:08 AM
Hi Jason,

Thank you very much for your clearifying nodes setup on SSS and the simple skin material.



It is still quite unclear to me what kind of textures should go into the Epidermis Color and Subdermis Color slot. Could you please further clearify this a bit to us. From what I have looked up about epidermis and subdermis e.g. in wikipedia, it seems that maybe some pigmented mole info or the hair roots etc. should be seen in an epidermis texture. The subdermis or rather "subcutis" is ought to contain blodd-vessels etc.

So is that understanding correct and are you using texture maps with such specific information contained or what colouring information would you suggest for each of the two slots?

Thank you in advance,

Robert

It all depends on the distance within the shot, the lighting and the condition of the skin you are shooting. But yes, if you want to be photoreal and have micro precision within your render you can add multiple colors such as red and blue veins in your subdermis texture color, most of which are very tiny and so appear to be patchy shapes of blended color. The epidermis consists of drier flakier skin and tends to have a dustier cracked look to it so your epidermal texture should reflect that. I guess you'd have to just get some really nice photo ref to know just how this stuff appears. The dominating color of your texture should be determined by the temp and condition of your lighting. I rarely rely upon only lights and GI, and shaders to get the color transitions to achieve the desired effect, it has a lot to do with the color textures too. Think of color textures as a local type of color and the other color tools as more global types of color effects.

rso
09-21-2007, 12:58 AM
Thank you Jason!

I hope that I can build up on what you've been saying ...


... if you want to be photoreal and have micro precision within your render you can add multiple colors such as red and blue veins in your subdermis texture color, most of which are very tiny and so appear to be patchy shapes of blended color.

I already tried that one time without convincing results though. So I guess one really has to be careful and experimental with the colours used for such elements like blood vessels for a subdermis texture since my "real life" referenced colours ended up in quite shrill tones of the shader node.


The epidermis consists of drier flakier skin and tends to have a dustier cracked look to it so your epidermal texture should reflect that. ...

Well, I hope that I understood that correctly. But maybe in some cases there doesn't necessarily be an epidermis map at all ...


The dominating color of your texture should be determined by the temp and condition of your lighting. I rarely rely upon only lights and GI, and shaders to get the color transitions to achieve the desired effect, it has a lot to do with the color textures too. Think of color textures as a local type of color and the other color tools as more global types of color effects.

Well that is the tricky question ... And it is kind of difficult to arrange the proper color and texture information for the diffusion, the epidermis and the subdermis textures ...

One time, I experimentally placed a kind of muscular map (like the one available on http://www.daz3d.com/i.x/shop/itemdetails/-/?item=3050) as subdermis color and it really didn't make sense at all. The result looked not at all realistic. So I guess that such texture information would be wrong. Maybe with the exception for the skin of the hands of elderly people, where you can strongly see the blood vessels and even tendons show through the epidermis.

After all, this is still a huge field of experimentation I guess ... And I need to scrape my money together in order to get the FPrime update quickly. Otherwise it's hardly any fun surfacing especially with the SimpleSkin node ...

jasonwestmas
09-21-2007, 10:46 AM
Well Ironically, it's not the muscle fibers themselves that you can see under the skin, it's the blood vessels in the skin that shows through; The blood tends tend to show through where the light can actually penetrate through the skin. Don't forget e.g. ears, nose, eyelids, lips will be much more suseptable to this effect and the Simple skin shader does do most of this by itself with little help. Nevertheless if you minimize your SSS effect (sss, which is just a fancy word for "more physically accurate" translucency) and then minimize color intensity with the tools NT gives you, that will give you more believable results.

jasonwestmas
09-21-2007, 10:50 AM
The epidermis backscattering is necessary in creating photoreal results. Your texture that you are using for your epidermis color will not be exposed to backscattering without epidermis turned on.

rso
09-22-2007, 05:14 AM
Hi Jason,

Thank you so much for your statements. You really seem to be an expert!