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SSS shaders
Posted: 29 March 2013 02:43 AM   [ Ignore ]   [ # 31 ]
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Sertorial - 28 March 2013 05:23 PM
Szark - 28 March 2013 04:20 PM

First off SSS is a raytraced function therefore it really does need Raytraced shadows to get the best effect. .

Hang on. I thought everything used raytracing in the 3D rendering world?

I thought 3d rendering was basically a mathematical model taking rays of light and making them interact with shapes and surfaces. Isn’t that the same as ray tracing?

Not exactly. Raytracing does exactly what it says on the tin and traces the path of the light from the source to the target, which can include bouncing off objects like mirrors for reflectivity. When it comes to shadows, depth maps trace the contour of an object taken from the light source to simulate where the shadow would fall, while raytracing naturally darkens the area because the light no longer reaches that part of the scene. Raytracing also does a far better job of passing through translucent materials.

There’s a whole raft of information on which one is best for which type of work you’re doing, but the basic upshot is that raytracing, while computationally more intensive, is a lot more accurate.

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Posted: 02 April 2013 08:37 AM   [ Ignore ]   [ # 32 ]
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Szark - 28 March 2013 11:49 AM

Yes but take a note of bump and displacement maps settings beofre doing so just in case. wink

But there is more work to set up the mats using SSS than justing loading and rendering…a lot more.

This aspect a lot of people have trouble with as there is a lot to learn so the question is are up for a real challenge and it will take a little time to explain all the setttings which also depend on the light rig. Bad lighting and SSS don’t mix.

Hmm… so here is a comparison. On the left is the so-called “simple” surface that comes with the character, in the middle is the SSS surface (both using the DS default shader). On the right is the SSS surface again, but this time I have applied the Ubersurface shader (ctrl-loaded, so as not to replace maps) The lighting is the same in all three cases - a distant light at zero degrees and 50% with a specular only spot at 45 degrees left.

Both middle and right (ie the fancy, schmancy SSS surface) look a bit odd. Why is that?

If I compare the two surfaces, the only difference seems to be that the “simple” surface has specular colour 100& black but the SSS has specular colour 100% white (which is probably why it looks so shiny!) and the “simple” has for its bump map just the same map it uses for the diffuse colour channel, whereas the SSS one has a proper black and white bump map.

Go figure!

 

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Posted: 02 April 2013 11:40 AM   [ Ignore ]   [ # 33 ]
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SSS with DS Defualt Shader….How? You only get Subsurface scattering with Human Surface (Skin) Shader and Uber Surface/2, in essence Uber shaders only. smile

Now the far left pic needs a lot of adjusting like specular settings, SSS, Velvet, Bump etc. Like I said it will not be a one click solution and if you want to learn to get good results then be prepared to change one setting and test render, change it back, change another and test etc etc until you understand what each channel does and why.

Or even better still is to remove the skin maps entirely and just turn off all the channels barring one. For example if you were testing velvet make the velvet colour bright or contrasting, say purple, then when rendered on the grey figure you see the effect (just like this http://www.daz3d.com/forums/viewthread/18364/P30/#271094 ) and the adjust one setting at a time and render to see what that setting does, only then will you understand what each channel does.

Then when you know what each channel does then you can reload the maps and set up the settings for that texture set.

Just remember that each channel works by itself, independently from each other and together they make the “whole”, understanding each channel will help you get that whole.

But to be honest there is no way I, or anybody for that matter, can help until we see your surfaces settings there are just so many settings.

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Posted: 03 April 2013 02:46 AM   [ Ignore ]   [ # 34 ]
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Szark - 02 April 2013 11:40 AM

SSS with DS Defualt Shader….How? You only get Subsurface scattering with Human Surface (Skin) Shader and Uber Surface/2, in essence Uber shaders only. smile

As I said higher up this post, the character comes with two folders. One labelled “simple” and the other labeled “SSS” in each folder is a .PZ2 file that loads the surfaces. Presumably in Poser (which the character was actually designed for) one loads a SSS shader and one loads a default shader. Loading it in DAZ however can’t call this and so the surfaces load with the DS default shader - I am guessing here… does that sound feasible?

Szark - 02 April 2013 11:40 AM

Now the far left pic needs a lot of adjusting like specular settings, SSS, Velvet, Bump etc.

eh? the left pic? The DS default shader doesn’t have a velvet setting. are you sure you mean the left pic? To me, that looks the most normal of the three. It’s the middle and the right one that don’t look right (these have the SSS .PZ2 file loaded.

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Posted: 03 April 2013 03:36 AM   [ Ignore ]   [ # 35 ]
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Loading a Poser SSS mat preset WILL NOT give you SSS in Daz Studio simple as that so yes you are correct it will just load a default surface. Forget Poser SSS in Daz Studio full stop.

And sorry my head is pretty messed up yes I meant to say right, my dyslexia kicking in again.

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Posted: 03 April 2013 03:41 AM   [ Ignore ]   [ # 36 ]
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Szark - 03 April 2013 03:36 AM

Loading a Poser SSS mat preset WILL NOT give you SSS in Daz Studio simple as that so yes you are correct it will just load a default surface. Forget Poser SSS in Daz Studio full stop.

And sorry my head is pretty messed up yes I meant to say right, my dyslexia kicking in again.

no probs! Thanks for your help (and patience with all my noob questions)

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Posted: 03 April 2013 03:44 AM   [ Ignore ]   [ # 37 ]
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I am wanting to help with this but I can’t tell what to do with every channel as you have to take your lighting , texture maps and the look you want to achieve in to consideration.

But I can give a starting point if you want?

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Posted: 03 April 2013 03:49 AM   [ Ignore ]   [ # 38 ]
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Szark - 03 April 2013 03:44 AM

I am wanting to help with this but I can’t tell what to do with every channel as you have to take your lighting , texture maps and the look you want to achieve in to consideration.

But I can give a starting point if you want?

I do understand what you are saying. The UberSurface is a complex shader an will take some time and effort to learn. The idea of trying out a channel at a time is a good one.

Some pointed to get me started would be helpful tho (I looked at Omnifreaker’s you tube video on UberSurface, but it’s not very helpful)

 

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Posted: 03 April 2013 04:16 AM   [ Ignore ]   [ # 39 ]
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OK give me a few hours (I have a visitior on there way round) and I will get something typed up.

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Posted: 03 April 2013 08:19 AM   [ Ignore ]   [ # 40 ]
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Diffuse Colour: Leave that for now we can change it later.

Diffuse Strength drop to 90 – 80%

Specular: In reality spec colour is always white; it is the surfaces properties that can give the spec colour so I generally use White. Well that is how I understand things. Some vendors use a light blue colour. It is up to you what colour to use.

Glossiness: About 30 – 40% should make a nice start

Spec Strength: 8 – 10%

Spec 2. I still don’t know what or why there is a Spec 2. But this is one of those setting that can only be set up right when you turn off Spec 1 and test the spec 2 only. When you have the desired effects then reengage Spec 1 and test.

Anisotropic: Not for skin. Metals and Glass etc.

Ambient: I never use Ambient on Skin…ever.

Reflection: Some folks use a Reflection with an Environment Map (HDRI) but I have never had much success with this. Given you skin is generally oily having reflection does make realistic sense. If you want to have real (raytraced) reflections at a very low setting expect a longer render.

Fresnel: Not on Skin but good for Eyes mainly the pupil.

Velvet: Colour well this is a personal choice but after some testing I found a colour similar to the skin colour best like a peach/brown, 20% strength and about 15% falloff

SSS

Colour I always start with a 128, 0, 0 red and adjust up or down if needed. Want more red SSS increase the red and vice versa. However if there is too much red burnt in the skin texture maps then injecting red here will make the skin appear more red. To counteract this drop the red channel in the diffuse colour.

Strength depends on a few things, like are you using SSS maps then 100% should do it. No SSS maps then 20 – 50 % might do it.

Refraction: This is a good one as most scientists can’t agree what the IOR of skin is as there are so many variables but a value of 1.39 – 1.41 should do.

Scale: is how thick the surface is before the SSS takes place. This is something else I need to test and we don’t really know what value this is. If it is the Daz Studio default then 1 = 1CM and our skin is so much thinner than that. I have been trying to find out. IMHO 4 is why too high if this is the case. But with anything like this I say just go with what works. LOL I generally use a value of 1 to 1.70 before someone got me thinking what the value is.

Group: Is for grouping any surface that has the same SSS properties this is so the render engine knows what SSS properties applies to which surfaces. I use SSS on Teeth and Eye whites which have different SSS settings so I make all the Skin group 0, Teeth group 1, Whites group 2 and so on. If you don’t do this the render engine will lump all SSS together and render the whites and teeth with the same SSS settings as the Skin.

Translucency: I never use for skin. The SSS should give use what we need.

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Posted: 03 April 2013 08:43 AM   [ Ignore ]   [ # 41 ]
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Szark - 03 April 2013 08:19 AM

Diffuse Colour: Leave that for now we can change it later.

Diffuse Strength drop to 90 – 80%

Specular: In reality spec colour is always white; it is the surfaces properties that can give the spec colour so I generally use White. Well that is how I understand things. Some vendors use a light blue colour. It is up to you what colour to use.

Glossiness: About 30 – 40% should make a nice start

Spec Strength: 8 – 10%

Spec 2. I still don’t know what or why there is a Spec 2. But this is one of those setting that can only be set up right when you turn off Spec 1 and test the spec 2 only. When you have the desired effects then reengage Spec 1 and test.

Anisotropic: Not for skin. Metals and Glass etc.

Ambient: I never use Ambient on Skin…ever.

Reflection: Some folks use a Reflection with an Environment Map (HDRI) but I have never had much success with this. Given you skin is generally oily having reflection does make realistic sense. If you want to have real (raytraced) reflections at a very low setting expect a longer render.

Fresnel: Not on Skin but good for Eyes mainly the pupil.

Velvet: Colour well this is a personal choice but after some testing I found a colour similar to the skin colour best like a peach/brown, 20% strength and about 15% falloff

SSS

Colour I always start with a 128, 0, 0 red and adjust up or down if needed. Want more red SSS increase the red and vice versa. However if there is too much red burnt in the skin texture maps then injecting red here will make the skin appear more red. To counteract this drop the red channel in the diffuse colour.

Strength depends on a few things, like are you using SSS maps then 100% should do it. No SSS maps then 20 – 50 % might do it.

Refraction: This is a good one as most scientists can’t agree what the IOR of skin is as there are so many variables but a value of 1.39 – 1.41 should do.

Scale: is how thick the surface is before the SSS takes place. This is something else I need to test and we don’t really know what value this is. If it is the Daz Studio default then 1 = 1CM and our skin is so much thinner than that. I have been trying to find out. IMHO 4 is why too high if this is the case. But with anything like this I say just go with what works. LOL I generally use a value of 1 to 1.70 before someone got me thinking what the value is.

Group: Is for grouping any surface that has the same SSS properties this is so the render engine knows what SSS properties applies to which surfaces. I use SSS on Teeth and Eye whites which have different SSS settings so I make all the Skin group 0, Teeth group 1, Whites group 2 and so on. If you don’t do this the render engine will lump all SSS together and render the whites and teeth with the same SSS settings as the Skin.

Translucency: I never use for skin. The SSS should give use what we need.

Awesome! Thanks. I’ll give that a try. Thanks SO much for taking the trouble.

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Posted: 03 April 2013 08:49 AM   [ Ignore ]   [ # 42 ]
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No worries. I hope helps. smile I just wish I had the time to get the tutorail finished…my life has just gone crazy in the last few weeks with no time to play and frying my brain. LOL

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Posted: 03 April 2013 09:09 AM   [ Ignore ]   [ # 43 ]
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Szark - 03 April 2013 08:49 AM

No worries. I hope helps. smile I just wish I had the time to get the tutorail finished…my life has just gone crazy in the last few weeks with no time to play and frying my brain. LOL

one question. I follow everything apart from the “group” part. I don’t see how that works? I ctrl-selected all the skin subgroups of the figure (torso, arms, face etc) and then applied your settings to them all.  Why would the render engine apply them to surfaces I havent selected?

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Posted: 03 April 2013 09:23 AM   [ Ignore ]   [ # 44 ]
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It is how the render engine works. If you don’t set different Groups for surfaces that have different SSS settings then 3Delight will treat them all the same so if I apply SSS to the teeth and don’t give it a Different Group number then 3Delight will lump the teeth in with the Skin SSS Settings and therefore get some funny looking pink teeth.

If you only use SSS on the skin then you don’t need to worry about this. But like me if you start to use SSS for Teeth and Eye Whites etc then the Group setting come in to Play.

Does that help? LOL

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Posted: 03 April 2013 01:12 PM   [ Ignore ]   [ # 45 ]
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Szark - 03 April 2013 09:23 AM

It is how the render engine works. If you don’t set different Groups for surfaces that have different SSS settings then 3Delight will treat them all the same so if I apply SSS to the teeth and don’t give it a Different Group number then 3Delight will lump the teeth in with the Skin SSS Settings and therefore get some funny looking pink teeth.

If you only use SSS on the skin then you don’t need to worry about this. But like me if you start to use SSS for Teeth and Eye Whites etc then the Group setting come in to Play.

Does that help? LOL

How weird. That doesn’t happen with any other channels. Normally you can ctrl-select different bits of the surface and just edit those ones. I wonder why SSS is different? It’s only a set of channels after all.

Maybe that’s why her eyes looked totally freaky, even tho I hadn’t done anything to them..

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