This is the basic Study Book about VRay Materials. Let´s learn together how different materials render and how to set up them properly.
The Basics of Materials
Materials are created using the Material Editor (I´m using Maya then we call it Hypershade) and at the first glance there are tons of options to choose from. Every single basic surface material would start as the VRayMtl and will come in a greyish color.
For this example I created a simple object over a plane ground, with one light and GI turned on. This is enough to have reflections, direct light and some soft shadows over a simple polygon object with concave and convex shapes. All we need is to work on the materials.
Let´s start with this Material. Creating this Material and assigning it to our model will render the most simple and flat surface. for this example I created two VRayMtl: one for the testing object (grey color) and another for the ground (orange color). The reason I choose orange (could be green, blue, red, any color) for the ground is that I want to get some color interference between both objects.
And this is the first rendered image. Check the rendering basic settings, tuned for a faster render without the much loss of quality. We can also check the rendering time (CPU consumption) on the lower end of the rendered image.
The very first item to look after is the Diffuse Color. As the name says it´s the most basic color option to set. It affects the overall appearance of the object giving color to it. See below some examples. The less color information your diffuse color is, the faster the rendering will be.
Also in Diffuse Color you can set it to a texture map. Clicking on the checker icon you will be prompted to choose what kind of map to link to this attribute. Choose File and then you´ll be able to map any image format file as the Diffuse Color. See below some examples of this mapping in action.
I´m using a JPG file, for example this one below:
And then, the Diffuse Color mapped with a JPG file, renders as such:
Amount is used to determine how much of this Material will be visible. It´s most commonly used in Multiple Materials setups where you can show more or show less of each individual Material on the same object. For this example it makes no sense at this early stage to change the amount for it will only look darker until it fades to complete black.
Opacity is set from 0 (transparent) to 1 (opaque) using all the range of greys and even a map to create procedural or textured opacity transitions. Using a value of 0.5 will make the object half transparent.
This slider gives you the option to make the overall aspect look
This is the attribute used to give Material an illumination value. If set to 0 it will be completely off, if set to 1 it will be completely bright (thus generating another light source on the scene). All the grey values ranging from 0 to 1 creates less and more bright light emission respectively. This also can be of colored color (see third example).
BRDF: Phong , Blinn and Ward
Now that we setup the most basic parameters such as diffuse color, opacity and roughness amount, it´s time to setup the second part of this material. Everything in the real world is at some point reflective. For this we need to adjust the Reflective settings on this material. The first one is to choose which calculation algorithm we would like to be rendered for this material (BRDF).
Phong is used to calculate the sharpest highlights.
Blinn is used to calculate the regular highlights. This is the most frequently used BRDF.
Ward is used to calculate the soft and spread highlights, making it ideal for metal alike materials.
Reflection Color is used to adjust the reflectiveness of the object at render. The value of 0 indicates that it will not reflect anything (reflective attribute is turned off), and a value of 1 indicates it will reflect everything at its maximum values, such as chrome materials does. In between values creates a huge amount of setup variations.
- Value: 0 (no reflection)
- Value: 0.5 (half reflective)
- Value: 1 (full reflective, chrome like)
- Value: Color (colored reflections)
- Value: Texture Map (using a checker map to create a pattern like reflection)
This determines the amount of reflection that will be rendered on this material. It´s another way to control how much reflection will be rendered, but only affecting it´s presence, not color.
Very slight and subtle changes to this slider makes huge impact on the rendered image and also on rendering time.
The default value of 1 indicates that the reflection will be sharp and mirror like.
Changing this value will blur the reflection, thus giving a more realistic feel.
Reflection Glossiness set to 0.98 will blur a little bit the reflections, and lowering this value to 0.9 will completely blur the reflection. Lower numbers (below 0.9) will spread even more the blurriness but won´t be so noticeable.
Fresnel Reflections happen on coated surfaces (like varnished floor or car paint), water, gems (jewels) and some metals. Fresnel Reflections happen to be more harsh and subtle depending on the standing point of the observer, this indicates that the inclination of the rendering rays will affect the reflectiveness of the material.
There´s a list of IOR (Index of Refraction) to use as guideline:
- Water: 1.33
- Plastic: 1.45
- Glass: 1.5 to 1.8
- Diamond: 2.4
- General materials (wood, stone, concrete): 3 to 6
- Metals: 20 to 100
Working with Hilight + Reflection Glossiness + Fresnel IOR
The combination of these adjustable sliders will produce most of the desired material reflectiveness and will make the object look clay, plastic or metallic.
Metallics (using Ward)
Plastics (using Phong)
Refraction happens when we have a transparent or translucent material, such as water, glass, crystal or jewels. The light that passes through the object will reflect with distortion (this is Refraction) back to the viewers standing point, bending the light the object looks like distorted. It´s very useful for realistic renderings, but will consume much more CPU and rising rendering time. Also, when refracting materials, it´s possible to cast these refracted lights on the environment, for example, the distorted light rays that happen through water surface and hit the bottom of a pool or sea.
On the Max Depth attribute you can set how far the light ray will pass through faces and bounce back to the camera until it reaches the amount established and then shows the Refraction Exit Color (in this case is black). Also, this object renders mostly orange because it´s mirroring the orange ground.
To enable caustics, you should first turn it on in your VRay GI tab (at the very bottom). Using caustics generates this light dispersion on the floor and all over the environment. While this particular example is not a very good one to show caustics, it would work better on a less complex object for the light would pass through less faces, generating clearer and more simple shaped caustics.
Caustics are thrown to the ground (these light splashes) and inside the model as well. Because there´s color aberration, then we have these multicolored spots around the model.
Fog is used to give color the right way to translucent refractive materials. The first example shows only color applied, therefore it looks way too dark.
Refraction IOR List
Below it´s a list with the most used Refraction Indexes:
|Acetone 1.36Actinolite 1.618Agalmatoite 1.550
Agate, Moss 1.540
Ethyl Alcohol 1.36
Glass, Albite 1.4890
Glass, Crown 1.520
Glass, Crown, Zinc 1.517
Glass, Flint, Dense 1.66
Glass, Flint, Heaviest 1.89
Glass, Flint, Heavy 1.65548
Glass, Flint, Lanthanum 1.80
Glass, Flint, Light 1.58038
Glass, Flint, Medium 1.62725
Jade, Nephrite 1.610
|Lead 2.01Malachite 1.655Methanol 1.329
Moonstone, Albite 1.535
Nylon 1.53Onyx 1.486
Opal 1.450Oxygen (gas) 1.000276
Oxygen (liq) 1.221
Quartz, Fused 1.45843
Rock Salt 1.544
Rubber, Natural 1.5191
Tiger eye 1.544
Water (gas) 1.000261
Water 35’C (Room temp) 1.33157
Zirconia, Cubic 2.170
Bumps are the second best friend of a 3d designer. It generates fake displacements simulating in and out bumps along the model´s surface.
To better understand, let´s take the cylindrical body of this model and assign a new VRay Material with everything reset, just adding a little bit of green color to its Diffuse Color. Navigate to the Bump Panel, below the Refraction Panel, and let´s add a map it´s attribute. It can be any image format file or procedural algorithm. For this example, I´ll be using a procedural Checkerboard.
When it comes to Bump mapping, the file you load as your bump should be grey scale because everything that is black will produce a bump inwards, and everything that is white will produce a bump outwards. The absolute middle grey (50% black) will produce no bump at all. So the grey tones, brighter or darker, will produce bumps according to their color value.
With a very fine and high quality image, using subtle Bump Multiplier, we can create a very realistic feel of most of the organic materials that exists around us. They all have, in some degree, bumps.
Lowering the values at Bump Multiplier you can get a very faint effect of this map along your object.
The basics of VRay Material was covered in this post, not going too much in depth but enough to experiment and learn the most used settings.
From the VRayMtl node it´s possible to tweak and change its settings to a wide variety of materials. The starting point usually is the basic VRay Mtl itself.
See below the final result tweaking some basic VRay Materials. Hope you enjoyed this.