TurboTips: V-Ray Fast SSS2 Material, Part 3

Calvin Bryson 3D Modeling, Artists, TurboTips, V-Ray FastSSS2 Leave a Comment

The following is an in-depth guide to the regular V-Ray Blend Material. In this series, we will cover the theory behind many of the features of the material.  We’ll also show specific examples of settings and give you some tricks to use. While the images used are from 3ds Max, the same concepts and settings can be used for V-Ray for Maya. Currently, the SSS materials in V-Ray for C4D behave differently, so this tutorial will not be as valuable for C4D users.

This week, we’re concluding this series of TurboTips with information on the Specular Layer; a few more settings for the FastSSS2 Material; and a sample workflow to help you put it all together.

Specular Layer

If you are familiar with the regular V-ray Material, this section will be very familiar to you. Basically, the Specular Layer is the same as Reflection, it’s just named differently. For physically accurate results, you must turn on the Trace Reflections option; otherwise, only fake speculars will be used.

There is no way to unlink the Reflection IOR from the base IOR of the FastSSS2 material. Most of the time, this shouldn’t be a problem, since that is the physically correct way to do it, anyway.

 

The Rest of the Settings

With the exception of the Diffuse and SSS layers, most of the FastSSS2 material is very similar to the regular V-ray Material, so all the same principles apply. You can also use maps in many of the slots that initially seem to support only colors (no little squares to set up maps next to color slots). Just scroll down to the Maps section and plug them in there.

 

Workflow Example

Let’s take everything we’ve learned and create a translucent material from a reference photo. We’ll attempt to make something similar to this jade:

 

Start by looking up the IOR for jade. Turns out, it is almost the same as glass: 1.61.  Let’s set it up on our material:

Next, we need to determine what type of scattering we need. In the reference photo, it looks like the material is a bit refractive (you can see through the thinnest areas). Let’s set up the Single Scatter mode to Raytraced (Refractive).

Next, we want to set up the basic look for the Reflections. Go to the Specular layer and make sure that the “Trace Reflections” option is on. It looks like the reflections are very glossy on this highly polished surface, so we’ll set up the Glossiness at 0.92. We also made the Specular color a bit darker [220;220;220] to make the reflections a bit more realistic.

Let’s see what we’ve got so far…

Now we are ready to move to the most important step: the Diffuse and SSS layer. We’ll start by setting up the Phase function to -0.8, since this is a stone type material. We’ll also bring up the Scatter Radius, since it looks like the light is scattered pretty deep within the object. Let’s try something like 30 cm.

At this stage, it looks like the Radius is a bit too large, but that’s ok.  We will use a Noise map in the Radius slot, which will be multiplied by this same value. So if we have Radius at 30cm and a medium grey map [128;128;128] in the slot, the actual radius will be 30*0.5=15cm.  This gives the material a quality where some areas appear less translucent while some are more translucent.

Here’s the noise map setup…

And here is the resulting render…

Now we need to set up the colors.  We’ll start by setting up this texture in the SubSurface color slot…

Now let’s tone the Scatter color. We want it to be more blue in the green areas, and more yellow in the yellow areas. This image doesn’t need to be too detailed, so we blurred it. This will also help with the foggy look.

The results already look pretty good. We just need to add a few small details to make it perfect.

We’ll use this gray texture in the Overall color slot to add some slightly dirtier looking patches to the object.

A variation of this texture can also be used in Spec color, Gloss and Bump slots to bring us to the finished material.

The material is finished. In this case, we did not need a Diffuse layer, since the outer/inner colors of the jade material appear to be identical.

As you can see, the idea is to take care of the technical details first (IOR, scatter type, phase, etc.), then tweak the artistic parts (colors/maps).

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This series of tutorials was made with our friends at Viscorbel.

If there are any topics you’d like to see in a future edition of  TurboTips, let us know in the comments below, or Tweet your question to @TurboSquid with hashtag #TurboTips.

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