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Vray MaterialsI will release my “Creating Vray Materials” video training

next week.

Originally I planned to make this theory part available only

for those who buy the video, but I’ve decided to share it with

everyone, so enjoy!

slow, noisy and non-realistic results. VRay is designed to be

used with it’s native shaders, so that is what we are going to do.

Now let’s look at the first section – Diffuse.

Think of Diffuse as the base color of the object. If you see a

tomato, you can instantly tell it’s red. This means that red is the

Diffuse color. It is a bit more complicated for very reflective or

very refractive objects, but we will look at those later.

VRayMtl allows you to choose a simple color as the Diffuse or

use a Map. You can use any Bitmap or Procedural Map in the

Map slot.

Here is an example.

The Roughness parameter can “flatten” the color transitions.

You can use it to make your material appear dusty and flat.

Here is an example with the same green material at 0, 0.5 and

1.0 Roughness.

Next section is Reflection

As the name suggests, this section deals with the reflective

properties of the material. Most real world objects are reflective.

Look at these photos of chrome and brick for example.

The reflections of the chrome are very strong and sharp, you can

instantly recognize it as a reflective surface. But what about the

brick? It might look that it’s not reflective at all, but in fact the

reflections are just weak and very very blurred. The only objects

that don’t reflect any light are the black holes   Keep this in

mind when creating the materials.

makes it fully reflective. All the gray scale values between

increase or decrease the reflection strength. The color sliders in

3Ds Max go from 0 to 255, this means that if you want to make

a material that reflects 50% of the light that hits it, you need to

set the value of the reflections to 128. Here is an example at 0,

128 and 255. Notice how the third image has lost all the Diffuse

color and is only showing the reflections. Reflections make the

base color weaker as they get stronger. The Energy Preservation

law doesn’t allow realistic materials to reflect more light than

they receive. This means that If the material has 0% reflections,

it shows 100% of the Diffuse color. If the material has 30%

reflections, the Diffuse color is weakened to just 70%, and so on.

Think of the reflections as a layer on top of the Diffuse, together

they create the final image.

The Diffuse color for all the examples is 128 gray. Notice how

the Reflect color changes the look of the Diffuse. This color

change happens because VRay adheres to the Energy

Preservation rule. If the material reflects the red colored light,

the red color is subtracted from the Diffuse and only green and

blue are left. This behavior can sometimes make it difficult to

predict the final result, this is why you can change the Energy

Preservation mode in the material options. If you choose

Monochrome, only the reflections will be colored and the

Diffuse color will be left unchanged.

Next up is Reflection Glossiness. This is the parameter that

controls how sharp/blurred are the reflections. Some real world

objects, like polished metal, mirror, chrome, have very sharp

reflections, while other materials, such as wood, concrete,

plastic, etc., have blurred reflections. You can adjust the

Reflection glossiness from 0 to 1 (completely blurred to

perfectly sharp). For most materials you will not need to lower

the glossiness below 0.3. You should always use blurred

reflections with caution, do not lower the glossiness more than

necessary, as this will cause more noise in your image, you can

get rid of it by increasing the Subdivs, but it will take a toll on

the rendertime. Here are some basic examples of how the

glossiness works.

Notice the noise introduced into the image. You can clean it up

with the Subdivs parameter, increasing it will make reflections

smoother at the cost of render time. Notice how the render time

has increased 3.5 times if you compare the third and first

images. 16 is a good choice for decent result without too much

waiting. You can use the subdivs parameter to find a balance

between time and quality.

Next up is the Fresnel parameter. You might have heard that all

real world materials feature Fresnel reflections, but what does it

actually mean? Fresnel changes the reflection strength

depending on the viewing angle. General rule is that reflections

are weaker if the surface is facing you perpendicularly and

increase in strength as the surface approaches parallel position

relative to your viewing angle. Here are some real world

examples where you can see this effect in action. The marble,

car and wall surfaces are much more reflective when they are

more parallel to the viewing angle.

And here is how the Fresnel IOR or Index of Refraction works.

Use only values from 1.01 up, lower values are not physically

correct for normal materials. Increasing the IOR changes the

relationship between the angle of the surface and reflection

strength, look at the examples.

As a general guideline, here are the Reflect IOR values for some

common object types:

water 1.33

plastic 1.45

glass 1.5-1.8

diamond 2.4

compound materials like wood, stone, concrete etc 3-6

metals 20-100

see, 6 reflections are plenty for this scene. Other scenes with

more reflective surfaces might need a larger value.

First parameter that controls the refractions is Refract color. As

before, it goes from black (no refractions) to white (full

refractions) and everything in between is a mix between Diffuse

and Refraction.

Here are some examples with a black material. I recommend

using black diffuse color [1;1;1] for most of the transparent

materials and adjust the overall color with Refract color and Fog

color.

You can use a color, bitmap or procedural map in this slot as

well.

Refraction glossiness. Just like with the reflections, you can

change how blurry are the refractions. This effect is great for

frosted glass or any other rough surface that lets through the

light but distorts it along the way.

This one increases render times and noise a lot so be careful

with it. No need to go lower than 0.6 for most materials.

To clean up the noise, we need to increase Subdivs parameter.

As you can see, getting a clean result comes with a huge cost.

The render time for the last image is almost 7 times longer than

with the default value. It is also 15 times longer than not using

blurred refractions at all! So try to minimize the blurred

refractions if you need fast renders.

In the real world light changes it’s angle as it travels between

objects of different density, thus the surface ‘refracts’ the light.

IOR value of 1 let’s the light through without bending it, as the

IOR value increases, so does the angle at which light is

refracted. Look at these examples.

Index of Refraction has been calculated for many materials, so

you don’t need to guess. You can find various IOR tables on the

internet. Here is one of them:

Acetone 1.36

Actinolite 1.618

Agalmatoite 1.550

Agate 1.544

Agate, Moss 1.540

Air 1.0002926

Alcohol 1.329

Amber 1.546

Amethyst 1.544

Crystal 2.00

Diamond 2.417

Emerald 1.576

Ethanol 1.36

Ethyl Alcohol 1.36

Glass 1.51714

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

Gold 0.47

Ice 1.309

Ivory 1.540

Jade, Nephrite 1.610

Jadeite 1.665

Lead 2.01

Malachite 1.655

Methanol 1.329

Moonstone, Albite 1.535

Nylon 1.53

Onyx 1.486

Opal 1.450

Oxygen (gas) 1.000276

Oxygen (liq) 1.221

Pearl 1.530

Plastic 1.460

Plexiglas 1.50

Polystyrene 1.55

Quartz 1.544

Quartz, Fused 1.45843

Rock Salt 1.544

Rubber, Natural 1.5191

Ruby 1.760

Sapphire 1.760

Silicon 4.24

Steel 2.50

Tiger eye 1.544

Topaz 1.620

Tourmaline 1.624

Turpentine 1.472

Turquoise 1.610

Water (gas) 1.000261

Water 35′C (Room temp) 1.33157

Zirconia, Cubic 2.170

Max depth works just like with the reflections. The default value

is usually fine, but for scenes with large amount of refractions,

you should increase it.

Next parameter is Fog Color. It is great if you want to tint the

glass in a realistic way. Using the Fog color makes thinner parts

lighter and thicker parts darker. You can use the Fog multiplier

value to adjust how strong is the tint. I suggest using colors with

less than 255 lightness and saturation for realistic results.

You can control the relationship between object thickness and

Fog intensity by using the Fog Bias value. Look at the examples

to see how it works. Negative values make the tinting stronger

and color transitions more extreme, while positive values make

the fog smoother and weaker. Use it together with fog multiplier

to get the effect you need.

The biggest drawback of the Fog color is that you can not use a

map in this slot, this means you can only use a single color. If

you want to create a stained glass material or glass with

multiple colors, you will have to do that by using the Refract

color and not the Fog. It is, however, great for those single-

colored materials and much more realistic than simply changing

the Refract color.

Dispersion also increases the render time.

First is the BRDF model. This parameter affects how the

specular highlights of the material are calculated. VRay offers 3

options: Phong, Blinn and Ward. Phong has the sharpest

highlights, Blinn is a bit more blurred and Ward is even softer.

Blinn is the default value and it is fine for most materials, for

metals you will want to use the Ward model.

Anisotropy allows you to create stretched highlights. In real

world these are most commonly seen on brushed metal surfaces

with long, parallel ‘scratches’. Anisotropy allows you to fake this

by stretching and rotating the highlights as you like.

This example shows how changing the Anisotropy value

changes the speculars. Negative values stretch them highlights

horizontally while positive values stretch them vertically.

And finally you can change the reference axis for even more

control.

Next comes the Maps section of the material. This is a

convenient list of all the slots you can assign bitmaps or

procedural maps to.

There are some important properties of the material that can

only be accessed through this section. These are Bump, Displace

and Opacity.

Let’s look at the Bump and Displace slots first.

Both of these slots allow you to assign a bitmap or procedural

map to simulate unevenness and deformation of the objects

surface. Bump does so without changing the overall geometry of

the object, but Displace actually subdivides and deforms the

object during rendering. The deformations work like this –

middle grey [128;128;128] of the map does not change anything

on the object, darker values push the surface inwards while

lighter values pull it out. The further this value is from medium

gray, the stronger is the effect. Color of the map is not taken into

account and only the lightness value is used.

Last map we are going to look at is the Opacity map. It works

very simple. Pure white value is used for the non-transparent

parts of the material and pure black is for completely invisible

parts of the material, everything in between is more or less half

transparent. It is great if you need to simulate stuff like tree

leaves or lace fabric without using a large amount of polygons.

Here is an example using the same map as in the Bump

samples.

The two next segments of VRayMtl are Reflect Interpolation

and Refract Interpolation. They are supposed to be a quicker

way for calculating blurred reflections and refractions, but I will

not be covering those, as I have often found troubleshooting the

issues/glitches that can appear from them take longer time than

rendering non-interpolated materials.

This wraps up the basic VRayMtl, it already allows you to create

90% of the materials you will encounter in your work. There

are, however, some special cases where other materials are

better suited.

Let’s look at the VRayBlendMtl. It is the perfect tool for making

compound materials.For example, if you need to create a black,

shiny surface with blurred gold spots, it is way easier to create

two materials and blend them together than hand painting all

the different maps you would need to achieve this effect in a

single VRayMtl.

base material and finally pure black doesn’t show any coat

material at all.

Each next coat layer treats everything above it as a single

material, if you have a base material and 2 coat materials at

50%, the result is 0.5(0.5base+0.5_1st_coat)+0.5_2nd_coat.

In this example I’ve added a second coat layer with pure green

diffuse color, if all 3 parts would be used equally, the resulting

color should be white (RGB at equal values result in grayscale

color), but it is instead a 50/50 mix of purple and green.

You can use up to 10 material in a blend (if you then create a

new VRayBlendMtl and keep the filled one as sub-material, you

can add 9 more materials, repeating this procedure gives you

unlimited amount of slots). Here is a somewhat more complex

example of a 4 material blend.

I am sure you now see the potential of VRayBlendMtl. I will

show you some practical examples on how to use it in the

videos.

Let’s move on to the next material type – VRayFastSSS2. The

letters SSS stand for Sub-Surface Scattering, another common

name is Translucency. This effect happens when light rays don’t

go straight through the object, but are scattered in multiple

directions when inside, this does not allow you to see through

the object, but you can see the light inside it. Unlike refraction

glossiness which scatters light rays at the surface, SSS does this

inside the object. This makes some interesting lighting effects,

the light penetrates the object and lights it from within. Some

real world examples are: flesh, milk, marble, jade, fruit, wax etc.

Look at these photos to see what I’m talking about.

surface while VRayfastSSS2 is more illuminated. The effect is

very subtle though.

Next parameter, SSS prepass, controls the accuracy of the

scattered light. Lower values give blurrier results, while higher

values give a more precise rendering, the precision comes with

an increased render time. For production renders, I suggest

using values of -1 to 1.

Fast SSS allows you to set the IOR as well. Most water based

materials like skin, milk, juice, plants have IOR of ~1.3, for

stone type materials 1.5-1.7 is more suitable.

You can also use the built-in presets to quickly create some

common materials, these are:

Skin (brown)

Skin (pink)

Skin (yellow)

Milk (skimmed)

Milk (whole)

Marble (white)

Ketchup

Cream

Potato

Spectralon

Water (clear)

First is the Overall color. This color allows you to change the

color of the whole material (the surface and the inside).

Look at the examples to see how this color changes the look of

the default VRayfastSSS2 material.

Next is the Diffuse color and Sub-Surface color. First one

controls the outer surface, second one controls the inside of the

object. This works somewhat different than VRaymtl. By

default, VRayfastSSS2 only uses the sub-surface color and

scatter color as the main sources of pigment. You can assign a

diffuse color and increase the diffuse amount to mix it with

those two colors. It is a bit hard to explain, I’ll show you an

example. Here I have assigned a Red Diffuse color and a Blue

sub-surface color. With the default setting of 0 Diffuse is not

seen at all, when I increase it to 0.5 it is a 50% mix with the blue

and finally, when I set it at 1, there is no more translucency and

only the red diffuse color is seen.

Ok, let’s look at the Scatter color now. The lightness of this color

affects how strong is the scattering effect. It get’s stronger from

black to white, as usual.

I’m using a simple grey material with red sub-surface color in

this example.

You can also use a saturated color in this slot to give a tint to the

object. It work’s best if you use a color that is close to the sub-

surface color. It also tints in the opposite direction, sounds

weird, I know. What it means is if your sub-surface color is red

and you set the scatter color as orange, the actual tint will be to

the opposite direction of the hue scale – purple. If you use

purple, the tint will be orange. Look at the pictures to see it in

action. The effect is subtle, but sometimes it’s just what is

needed!

highlights just like with the VRaymtl – by changing the

glossiness value.

There are 3 possibilities you should use depending on the

material you are trying to create.

Simple mode is best for materials where the light doesn’t go too

deep, best examples are skin, plastic.

Refractive mode is great for materials that are very translucent

but at the same time quite opaque (marble, milk)

Refractive (raytraced) mode is for more transparent materials,

this also creates nice refractions and transparent shadows. Use

it for materials like glass, water, crystals.

For the best results, turn Front lighting, Back lighting and

Scatter GI on.

Ok, so that’s enough theory   I’ll show you how to use this

knowledge in practice in my “Creating Vray

Materials” training video!