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.
To wrap up this series, we’ll show you an example workflow for creating a material from scratch. It’s not set in stone and you can change the order around, as long as you’re paying attention to the general principles.
It’s always a good idea to have a reference photo (or multiple photos) so you can see what the goal is. Don’t focus on using your references to make an exact replica, but use them as a guide to creating a similar look.
First, decide on the Diffuse color. All materials can be split into roughly three groups: Reflective (Metals), Refractive (Glass, Water, etc), and Other (almost everything else). For Reflective and Refractive materials, you can just choose a dark grey color like [1;1;1]. Since our reference photo seems to be some sort of plastic (Other), we need to visually choose a color for its Diffuse- something like this blue/black will do.
Next, add a few Reflections. Don’t worry about adding all the little details just yet. So far, the Reflections will only help to evaluate the shader better. Let’s start with a simple color [180;180;180] and set the Fresnel IOR to 1.45 (plastic).
Try to estimate the general Glossiness at this point. The goal is to roughly match the size and shape of the highlights on the reference photo. It looks like 0.85 will do the trick:
Adding a BumpMap
Try to imitate the way this ball has been used and abused- it has all sorts of scratches and rough spots. Pick a similar texture and use Levels in Photoshop to make it so that all the bumps and scratches are black/dark grey, while the base color is [128;128;128].
Use this map in the Bump slot; reduce the Blur to about 0.5 to make everything a bit sharper; and reduce or increase the Bump strength until it looks right.
Adding a ReflectMap
Now we need to think about how this sort of damage would affect our Reflections. It would likely make them a little bit weaker and blurrier, since the scratches are not smoothly polished, but more rough (at least the deeper ones).
So, let’s take the bump map, adjust the levels so that the white point is at 180, and move up the black point to about 150. Since there are probably some areas that are also a bit dirty or oily, add another layer with some patchy areas on top of this map and set it to Overlay mode.
Adding a GlossMap
For the Glossiness map, calculate the value that’s needed to match the test render. Here, we’ve set it at 0.85, so we need 255*0.85=216 as the main color for the texture. We’ll also move the black point to 128, so the lowest glossiness level is about 0.5 (255*0.5=128). Now that it’s done, perhaps add another overlay layer on top to add some slightly different details.
Make sure to set the Gamma to 1 for these b&w maps to get correct values in 3ds max. We also reduced the blur to about 0.4:
Starting to look better.
Adding Complexity To The BumpMap
Now all that’s left is adding another layer to our Bump texture (some sort of noise for a more realistic surface). Just add another layer in Photoshop, or you can set up a Composite map in 3ds max and overlay procedural noise there.
Adding Even More Texture
Almost there! As a final touch, we’ve swapped the Diffuse color for a Texture. A few gray/brown patches on top of dark blue will be a good fit.
Looks about right. Perhaps the scratch pattern is a bit rougher than the reference image, but otherwise, this looks good.
Always try to analyze your reference image and break it down into components – Diffuse; Reflection; Refraction; Bump. If something is not clear right away (for example, bump) add some reflections and it will be much easier to evaluate the other aspects. Everything goes hand-in-hand, so don’t forget to analyze how each element affects the others.
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