sss workflow in actual production

[satzy6699]

Hi ppl,

sss looks great on my pc but can somebody point me out to how sss is actually used in a production environment where network rendering is used ! R there any issues in rendering out the passes and how the passes r composited n such useful stuff.

[daddyo]

there are no issues with rendering SSS in production, it's a shader that works as well as any others. Physical SSS, which requires photons, works just as well as any other caustic effects being rendered over a network, ie you are better off rendering multiple frames per node.

Typically, if you do break off the sss contribution into its own pass, the comping is very straightforward, and consists of doing an add operation back on your diffuse. Hope this helps

[satzy6699]

Thanks daddyo for the reply.

[liqueo]

I use sss skin frequently and you can get a lot of control by splitting up the shader into different render layers to get each layer out by itself. While some places may automate this, I don't have a programmer on staff so I set it up manually and it's fairly easy and quick to do if you are familiar with render layers and overrides and know how the shader works. I think there is also a MEL script on creativecrash that will do this using frame buffers, but I'm not sure how deep it goes. Check out modulok's tut on this site for an in-depth look at how the shader works.

Basically you create your shader on your master layer and then create a render layer for each part of your sss shader, i.e. diffuse, epidermal, subdermal, back scatter, primary spec, secondary spec, and reflect.

To do this, you would create layer overrides on the scatter weights, spec weights, diffuse weight and reflect weights. setting them to 0 will turn them off. For the spec layers I think you can also override the spec color and set it to black to negate it.

This method works really well as it gives you each piece of the shader as it's own file that you can comp. Make sure you also render out a luma matte for your objects. You don't want to composite these layers with alpha or you will start to get aliasing on the edges as the layering builds up. Instead, render them with no alpha, then after you comp them, you would use the luma matte for that pre-comp. Not sure what you composite in but if you use After Effects you would have the sss comped in it's own composition and then use a track matte of luma in your main comp with the luma matte above the pre-comp in the timeline.

Hope this helps.

[Crispy4004]

You may want to look at how Luma Pictures handles SSS. They use a single SSS pass which is independent of the color and diffuse lighting passes and puts them together in post:

Here is my adaptation of using their Method:



It's a completely different approach from building everything through the SSS skin shader. Instead, you only worry about the look of the SSS in Maya, then handle the skin texture addition in Post. Takes a way less time to get skin looking right.

[satzy6699]

Thanks a lot ++Crispy4004++ and ++liqueo++ for sharing this info, very interesting.

[liqueo]

No problem. I'm glad he put up screenshots because I didn't have time to and that's exactly what I was talking about.

I even experiment with layering different passes and different shaders to get a look that would be impossible through a single shader. There's no rules to making something look right so have fun and experiment with things. If you can look at something and break apart it's elements in your mind and think about why it looks like metal, or duck fat, or the hoof of a new born yak, you can then start thinking of how to make each part and assemble it in 3D. Just pay attention to render times as you don't want to have 100 render passes for a pebble. Not good for deadlines

Many times I wanted a nice rim light effect, so I would take a car paint shader and turn everything off and the colors black except the edge lit color (I think that's what it was called) which I would make white or a light color. Then I'd render it and just screen it in the comp.

BumpCombiner, Mix20Layer, p_MegaTK and other p_shaders and JS_shaders are also great additions and allow for some cool effects not available in stock MR shaders. They're free and available on all platforms.

And if you start messing around with maya utility nodes you will be able to do even more cool stuff. I managed to make an object dusty by having maya figure out which polys were facing up in the Y by using utility nodes, and then I used a ramp to mix the dust shader and the base. About 40 nodes in all but I got incredible flexibility, could control the look of the dust including procedural textures and bump, where it started and stopped, the falloff, , and overall a damn good result without having to use 3rd party shaders or have a custom one made. Maya can do so much but you might forget it has a lot of great tools because it can be overwhelming with how much is in it.

[liqueo]

I would like to add that Crispy made an excellent point. You don't need to use all of the SSS shader. Use what you need, dump what you don't try rendering them together with no diffuse and see how it looks compared to comping them separate. Even render out multiple passes of skin layers with veins and fat and muscle and paint masks to reveal them. You can an alternate shader for the skin itself if it looks better and it may even render faster.