Creating Photorealistic VRay Materials

Fine tuning VRay materials can be somewhat time consuming, but if you really want to be step ahead more close to photorealism, it’s a bet that you should take – the benefits are far better than the time consumed to research the issue. So let’s dig in VRay materials!

If you checked the previous article that is actually similarly related to basics of VRay materials as this one, or, if you already know some things about VRay materials  (I’m talking about really knowing, not “I heard about it stuff” thing), here are explanations are rendering examples of some advanced material setups so you can take the next step to mastering your VRay materials knowledge.

In the previous article I started with displaying a simple scene with some objects (the coffee scene) and I promised to explain how I did set up those materials. Here, we are going to do a step by step tutorial about that, and touch some more possible scenarios that you might need when defining materials for your render projects.

Before we continue, let’s take a flashback and check out the coffee scene rendering once more!

Coffee scene rendered using VRay

Fine Tuning VRay Materials

As we previously learned the basic VRay material settings, we shall learn now how to properly combine and use all of it’s properties. We shall now go over each material, except the materials from the background (the sofa and the floor).

Ceramic

Let us start easy by analyzing what settings we need for ceramic. I presume that you are more-less familiar with the VRay materials subject, so you basically know these at least in theory. So, the best would be if you have an object that is made of ceramic (coffee cup maybe?). OK, I’m sure you do have some objects that are made from that material, so do yourself a favor: grab it and start the visual analysis.

A regular (non-trained) person would say it’s only a coffee cup or a ceramic figurine or whatever the object is, but you, as someone who is in the rendering business should be able to tell much more. Namely the main characteristics of that material. So, fire up 3D Studio Max (or Maya, or whatever you use with VRay) make a new VRay material and let us start filling in the data.

The first one is the diffuse color or texture. As in this case we can use only a color estimate, we shall do so. Ceramic usually has a bright, clear white diffuse color. Set it so, but beware that perfectly white objects in real world are very, very rare. So instead of taking the color value scroller and cranking it all the way up set it to a bright gray (RGB: 200/200/200).

Intermezzo: Color values in the real world

Here, we shall take a small detour from the main subject which is actually still connected to the VRay materials setup. Let me share a tip with you – and you can test it for yourself too.

Make a very simple scene, a room without windows (draw a box, convert it to a poly, invert normals) place a cube and a sphere in there, and a light. Now, create a new VRay material and set it’s diffuse color to full white. Set up the renderer to do indirect illumination and render the scene. You will probably play a bit with the light intensity to get the illumination right. One important thing: set the color mapping type to exponential as it is the way that things work in nature. Once you get a decent rendering (light amount), it should look something like this:

Full white diffuse color - problem with rendering

Nope, there is nothing wrong with VRay, it’s the settings you use. As it’s painfully obvious, this scene has no contrast. Yes, the full white color of the objects is creating this effect. So, when you are defining your VRay materials, you need to keep in mind that even such a trivial setting as the diffuse color can and will have a big effect on your rendering. Even if you use the linear color mapping model, the contrast will still low or mediocre.

Let me explain what is going on here with this example. As you set the color in the VRay materials for the object to full white, the photons are bounced off the surfaces all over the place and practically nothing is “eating up” the light. There are similar effects that can happen on other material properties, so I advise you to instead of downloading the first VRay materials database you find (and using it without ever testing them out), please, I do urge you to experiment and use your brain. That’s what will make you different and better as an artist or a professional (or both) from others. Not that all those share-ready materials are bad, I’m just trying to explain that it’s better to know how things work so once you got a real job on your hands or some project that is important for you, or already there and holding your head without knowing what the problem is – so instead, you are “in the zone” and a pro. I revoke the said about downloading of VRay materials libraries if you are planning to back-engineer those – that is a good idea if they are giving good results.

Ok, now lower the diffuse color to RGB: 200/200/200, crank up the light source power to 500% of the previous value and hit render again. The result should be close to this:

Light gray diffuse color - a much better solution

Much more contrast now. Good. I could have increased the light amount a bit more than 500% though.

OK, back to our VRay materials now.

Porcelain/Ceramic

Porcelain/Ceramic VRay material

Once you set the diffuse color to a proper value (can be set a bit higher than the recommended 200/200/200 value), let’s move on to the next part of setting up ceramic VRay materials.

Porcelain is a reflective material, and is usually slightly blurring the reflections. It also can be pretty much characterized as a material that has Fresnel reflections. The strength of the reflections (Reflect color value) can differ because it can be set pretty low if you are not using Fresnel reflections, or close to full white if you do so. You won’t make a big mistake in either cases.

We shall set the Reflection color to RGB: 200/200/200, same as diffuse color. The Reflection glossiness is at 0.85, Subdivs to 16. Now, regarding this parameter (reflection glossiness), you can play with it a bit. You will start to get hang of how much you need to put this value to to get the glossiness value you need not only for this material, but only from looking at something what you see in the physical world. Experience will give you that you “see” VRay materials characteristics in the real world.

Next, turn on the Fresnel reflections and click on the “L” letter beside the option. This VRay materials option is a lock that locks the value to the Refractive IOR. Once you unlock it set to 1.8. The higher the value to more reflections from surfaces that are towards the camera. Appropriate values for porcelain IOR are from 1.2-2, depending on the effect you wish to achieve.

Wood

Wood VRay material

For creating VRay materials for wood, the first thing you need is a good wood texture, preferably tileable. Load it to the appropriate material slot once you got it. There are number of ways to get your hands on good textures. Either take a camera and do photos of materials/textures you have at hand, or just type “free textures” in Google and there you have it.

Once you have that, set the Reflect color value RGB: 170/170/170, and fire up the Fresnel reflections too. Unlock the IOR and set it to 2.4. If you use lower values the table (I’m talking about the example render, the first image on this web-page) might not do reflections where you want it, so specially on the scene setup I used, I needed a table that would reflect a bit more, so I put in a bit stronger value. This is an appropriate value for surfaces that are “quite” polished.

The Reflection glossiness needs to be set to 0.9, and the Subdivisions value to 32. The lower the Reflection glossiness is the higher the Subdivision value is to be set – if not you will get noise on the surface because there are not enough samples collected to calculate a valid light solution for the pixel/object in question.

Note that this value seems to be a sample grid definition, so a value of e.g. 8 VRay makes 8×8 ray samples from the point in question – beware, the higher the value it needs exponentially more time to render. So, be careful not to put in values that are too high but produce no visible enhancement to the rendering. I personally never used values higher than 48, and I figure that values higher than 64 have no sense except in really, really rare situations of creating some really not standard VRay materials.

(There is no) Metal Spoon

Metal VRay material

Just kidding, here it is! So, rendering metals are a bit tricky thing regardless if you are using VRay materials or default Max’s materials. It took some time before I figured out what the diffuse color of metals are. It’s close to black, at least in our spoon case.

No, I’m not kidding. Try it. If you set the Reflection color of the material to full white (full reflection) it will become a mirror. If you lower that value (to RGB: 190/190/190, however metals can have much lower values than that and still reflect a sufficient amount of ligth to look metalish), as metals do not have such a profound reflection value, the reflections will be less prominent, and the diffuse color will kick in. Try setting the diffuse color to white – you will get a very smooth plastic material, or something similar. Lower the diffuse value to gray – it’s much closer. Set is to nearly black (RGB: 4/4/4) and you are getting something that looks like a highly reflective metal.

See that I set the value close to black? As previously stated, the extreme values kills reality in the rendering. So, there is NO clear black in nature. Except if it’s a brand new secret military aircraft painted with some special “really and totally black” color which is usually not the case, and they generally never occur in nature (don’t grow on trees) so forget full black. Always go with non-extreme values when defining VRay materials.

Note that different metals have different color values, but for the situation here, the diffuse value is good to be set to very low.

Now, to get rid of the mirror feel of our metal VRay materials, set the reflection glossiness to 0.98 (or a bit lower, e.g. 0.9 ).  Metals that are brushed to be highly reflective have basically no Fresnel reflections, so leave this one off. However, you might use Fresnel for rendering metals that are not so polished, for instance metal parts of a tool. For these material types the Reflection glossiness is lower.

More VRay Materials

Basically that is all I wanted to introduce to you in this article about VRay materials. The only significant property that I did not elaborate about are refractive materials (glass, water, diamonds…) because it deserves a separate post/web page – the subject matter is a bit more complex, so I’ll need more space to wave around. However, the material is under preparation and will be available soon. Correction, I added the post! Click the link to check out the Glass and Refractive VRay Materials!

Other than that, the main point of this article is to teach you about setting up your custom VRay materials, and that there are rarely absolutely clean colors/values of materials in nature. Failure to respect that will result in a rendering that will look like rendered, and not our goal – rendering photorealistic scenes using Vray materials settings that are precisely set to do the job.