TurboTips: V-Ray Material, Part 4: Translucency & Bump

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

In this series of Turbo Tips, we’re giving you an in-depth guide to regular V-Ray Material. We’ll cover the theory behind many of the features of the material and give you specific examples of settings and tricks to use. While the example images are from 3ds Max, the same concepts and settings can be used in V-Ray for Maya. The information covered here is generally useful in V-Ray for C4D, but the specific fields and values may be different.

 Last week, we talked about the Refraction tab.  This week, we’ll be moving on to Bump, but first: a quick tip about…

Translucency

It is possible to add Translucency to your V-ray Material, but we highly recommend using VrayFastSSS2 material if you need this effect. Why? It’s a newer, faster interpretation of Subsurface Scattering that is also more adjustable.

If you do decide to use the Translucency in the regular V-Ray Material, here are a couple of things to remember:

  • The material needs to be refractive for translucency to work

  • Set the IOR to 1

  • Make sure that ‘Double Sided’ is turned Off in the Options tab

  • Reduce the Refraction Glossiness to something like 0.15~0.5

 

To define the outer color of the object, use the Diffuse color:

To define the inner color, go ahead and Fog Color, just like you would for refractive materials.

You can also tint the inside of the material by using the Backface color:

Stick to the Hard Wax or Hybrid type (Soft Water is just for legacy V-Ray version compatibility):

You can reduce the depth of the scattered rays by using the Thickness parameter:

Scatter Coefficient changes so the light rays travel within the object. Zero (0) means that the rays get scattered in all directions; one (1) means the rays will continue to move in the same direction before entering the object.

Light multiplier allows you to change the strength of the light as it moves inside the object.

Bump

 

Bump is another very important component of a V-Ray Material. All objects should have some sort of Bump, even if it’s just a very weak one. The thing is, nothing is ever completely flat, round, or in any other perfect shape. Even the smoothest, nicest surface has a bit of  imperfection to it.

The way this works is very simple: you just add a Map or a Texture to the Bump slot and adjust the strength.

Medium gray [128;128;128] does nothing, while lighter values go up and darker values go down (relative to the surface normals).

For very strong Bump effect, or for situations where correct shape in the profile of the object is needed, it’s better to use Displacement (either in a material slot or as a V-ray Displacement Modifier). Bump is a fake effect, while Displacement produces actual geometry at render time.

Just keep in mind that displacement works only in a positive direction. Black is in the original shape of the object and everything lighter than that gets displaced upwards.

Being Mindful of Gamma

If you want your Bump or Displacement to be accurate, you need to load your grayscale image with Gamma 1.0. Otherwise, the Gamma-corrected tones do not produce the expected result. For example, in the image below, the Gamma 2.2-corrected texture bumps the white color more than the black, while the Gamma 1.0 image behaves as expected.

 

Normal Maps

If you are using Normal maps in your workflow, you have to set up a Normal Bump map in the Bump slot. This will allow you to use the Normal map plus an additional Bump map. You can adjust the strength of each one individually. Normal maps also require their Gamma to be set up at 1.0 for correct results.

 

Boosting Realism

One last, but important, note: we do recommend adding a Bump map to all the materials you create. It doesn’t always have to be strong or detailed. Sometimes a simple Noise map can go a long way in avoiding that “fake” or “CG” look.

 

Next week: V-Ray Material, Part 5: Basic Workflow

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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