V-Ray Material, Part 1: Diffuse

by Calvin Bryson

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.

The VRayMtl is the main workhorse for creating shaders in V-Ray. Eighty percent of the time, it is all you‘ll need to create realistic results that

also render quite fast. It is optimized to work with all other aspects of V-Ray (lights, GI, sampling, etc.), so it should always be used instead of

3ds Max native materials.

Main components

Generally, the main components of a CG shader are:

Diffuse

Reflection

Refraction

Bump

These are the names that V-Ray uses. They may have different names in different renderers, but the functions are pretty much the same.

Diffuse gives the basic color to the shader; reflection controls how the the shader reflects light; refraction controls how it lets the light through;

and bump simulates a distortion of the object‘s surface.

With the exception of the refraction, the other 3 components should be present in all materials.

This week, we‘ll talk about the first of the main components:

Diffuse

The easiest way to understand Diffuse is to think of it as the color of the object. For example: what color is a tomato? Red! So, the Diffuse color

of a tomato is a red color.

Adding Realism with Variation

But wait! Most objects have a multitude of colors in them. Even a tomato has a light green patch where the stem connects to the fruit. The red is

not the same in all spots, so it could be more pink on the bottom and slightly greenish on the top. Most of the time, you should use an image (a

Texture or a Procedural Map) to define those colors. Even objects like a blue plastic ball are not perfectly blue a couple of days or weeks after

they leave the shop. Everything gets a bit dirty or faded out there in the real world.

The obvious exception to this is if you are creating shaders for studio renders of product design, where everything has to look like it just came

out of the packaging box – clean, shiny, perfect. In this case, you may use solid colors as the Diffuse of your VrayMtl. Use your judgement and

decide whether the material needs to be super slick for a studio render, or a bit weathered to make a believable real-world scene.

Setting Up the Diffuse (2.2 gamma Workflow)

Ok, so how do we actually set up the Diffuse?

You can either use a color, by clicking on the color swatch (green rectangle, above), or you can set up a Map by clicking on the small square

next to the color swatch (orange rectangle, above). You can also scroll down to the Maps tab and assign the texture there. Most maps in V-

Raywork this way (below)…

If you are working by eye and accurate colors are not required, choosing the color from the 3ds Max color picker is fast and easy. The problems

start when you want to match a color from an external application like Photoshop. If you choose the same RGB value in both applications, the

result will be different (if you are using proper gamma 2.2 setup in 3ds Max).

This problem comes from the Gamma correction. Essentially, the RGB values are brightened in 3ds max with the Gamma curve.

To fix it, you must use a Vray Color map in the Diffuse slot.

Set the same RGB values in the color slot and change the Gamma correction settings to ―specify‖ and make sure it‘s set at 2.2

Now, the color of the material matches perfectly with the color you took from Photoshop.

This may seem a bit complicated for just getting a simple color in 3ds Max, but currently, there is no automatic way to do this.

IMPORTANT NOTE:

For realistic results, the Diffuse must use colors or textures in the range of 10~230 on the lightness scale. Most things we think of as pure white

are actually ~75%-90% white (190-230). The whitest snow has only 90% albedo (reflectance rate). The same goes for blacks: only black holes

absorb everything and the rest of the world reflects at least a small portion of the light. Even the darkest coal has an albedo of ~4%. Using

overbright colors will not only look non-realistic, but it will also increase the render times as the light needs to be bounced around more.

The 10 to 230 range is for Photoshop textures and Vray Color gamma-corected colors. If you use the regular color picker, the range gets

converted to about 1~205.

If your Texture image has brighter or darker areas, it’s easy to fix using the Levels tool in Photoshop: just move the Black point to 1 and White

point to 230 as in the example image below.

Using Bitmaps and Understanding Filtering

Now let‘s try using our adjusted Bitmap in the Diffuse slot.

So, here is our next problem– notice the blurry areas on our model.

This blur is caused by Texture Filtering. It is used to avoid moire artifacts on small, sharp patterns by blurring everything.

Obviously, this is not at all what we want. We want nice, crisp renders. There are a couple of ways to solve this problem.

You can reduce the blur setting in the Bitmap Coordinates tab. Something like 0.01~0.6 is usually the most useable range. (See below.)

Another option is to disable the filtering altogether in the Bitmap Parameters tab. This works just as well for making everything sharper, but is

not as flexible. Most of the time we prefer reducing the Blur so we can keep at least some control over the softness of the texture.

It is very important to reduce blur or turn off filtering for all the textures you are using. Especially so with the Diffuse and Bump textures. If you

do not do this, there will be parts of your render that will look ‗blurry‘, not to mention loss of the fine details in textures. Keep in mind that

sometimes, the results might be too sharp. In that case, slowly increase the Blur value until the render looks good.

Diffuse Roughness

The Diffuse tab has one more option: Roughness. It controls how ‗flat‘ the shading of your object looks.

There are not a lot of materials where it is useful, but some common examples are chalk and dust. Higher values, flatter look: use your eyes to

make a judgement on how much the materials need it.

Diffuse Color vs. Refraction/Reflection Color

To wrap things up on Diffuse, let‘s talk about one more important point. Sometimes the Diffuse color is not obvious. This happens with

materials that are identified not by their Diffuse color, but by their Reflections or Refractions.

The most common examples are metals and glass. For extremely Reflective/Refractive materials, use near black as the Diffuse color [1;1;1;]. If

the material is ‗aged,‘ you can increase the lightness a bit, but try to stay in dark grey area of the lightness scale. This is just a general guideline–

sometimes you might need to give a bit of a color tint to a metal (or glass) to match your photo reference– but still, be start with near black and

adjust it only if necessary.

To illustrate this example, here‘s a gold material (below). To the left, you have an incorrect approach with yellow Diffuse and yellow

Reflections, and to the right, you have a physically correct look with near black Diffuse and yellow Reflections.

—

V-Ray Material, Part 2: Reflection

by Calvin Bryson

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 Diffuse tab. This week, we‘ll be moving on to:

Reflection

After Diffuse, Reflection is the second most important component of the VrayMtl. It also features a lot more options than Diffuse.

Perhaps it can be easier to understand how the Reflection works if you imagine it as a layer on top of the Diffuse. At 100% strength

[255;255;255], it shows pure reflection of the environment, lights, etc. Use a darker color and the Diffuse will start to show through. Drop it

down to pure black and only the Diffuse is visible. (It‘s not entirely as simple as that, but that‘s the general idea on how Diffuse and Reflection

interact.)

Adding Realism with Texture

The Reflections (just like most other maps in V-Ray) can be defined by using a color, a map, or a texture. The same principle of Diffuse map

applies– if it‘s not a shiny, slick studio render, there are bound to be some imperfections in the reflection amount. Also, it‘s best to use a Map or

a Texture instead of a simple color.

In general, it may be best to keep the Reflection value in the range from 1~230 for realistic results.

Always Turn on Fresnel

So, why does our material look so artificial?

The problem is that the light reflects equally at all angles. Real world objects have different strengths of reflections, depending on the viewing

angle relative to your line of sight. In general, the lower the angle, the stronger the reflection becomes. Even when some materials initially

appear to be non-reflective, they will reflect quite a bit when they nearly parallel to the direction you‘re looking at.

Let‘s look at some examples…

Notice how the reflection gets stronger as the floor goes further from the camera (or the closer it approaches the edge of the bowling ball). The

smaller the viewing angle, the stronger the reflection. If you look directly at something (90°), the reflection is much weaker than if you look at it

with a small angle.

To imitate this effect in Vray, you can use the Fresnel Reflections option.

In general, it is a good idea to use Fresnel for every material you create. The difference between chrome and concrete lies in the Fresnel IOR

value. This value determines exactly how this reflection falloff occurs. To access it, turn off the L button. (Note: the default value of 1.6 is only

good for glass and maybe some plastics.)

Below is a general guide on which values to use for which materials.

water: 1.33

plastic: 1.4-2.4

glass: 1.5-1.8

diamond: 2.4

compound materials (wood, stone, concrete, etc.): 3-6

metals: 18-100 (Though you should rarely exceed 40)

Reflection Glossiness

This parameter controls how glossy our material looks. The higher the value, the higher the glossiness. A perfectly polished surface would have

a glossiness of 1 (default value). Since nothing is ever perfect, we wouldn‘t go higher than 0.99

Decreasing glossiness makes the reflections blurrier. The effect is somewhat similar to taking a fine sandpaper to our shader and roughing the

surface up. This comes with a cost, though: the more blurry your reflections get, the harder it is for V-Ray to calculate them; thus, the result is

noisier and the render time increases. For very rough surfaces, we wouldn‘t go lower than 0.35

This gives us a useable range of 0.35-0.99.

Unlinking Specular & Reflection Glossiness

By default, Reflection glossiness and Highlight glossiness are locked together. However, there are times that it can be useful to unlink these and

use a slightly lower Highlight gloss. The effect is that you still have sharp reflections with some slight glow around them. Many real world

objects show this kind of behaviour:

This little cheat helps us simulate that look without increasing the render time. There are no rules on how much to lower the Highlight gloss, so

use your eyes to make the judgement– although, generally, a difference of 1.0 to 1.5 works well.

Using Texture To Drive Glossiness

As soon as the object leaves its packaging and a person touches it, the reflections are no longer equally glossy. The areas touched by hands or

scuffed against something rough are slightly more blurry from oils, scratches, or any other interaction with the world. Try to use a texture or a

map instead of a simple color– it can have very little variation in brightness, but it is important to pay attention to these little details. Otherwise,

the result will look artificial.

Generally, it is a good idea to derive your glossiness map from the reflection map (you can overlay a different texture to make it more

interesting). The areas that are less reflective will probably be slightly more blurry as well. This is not a hard rule. You can break it, as long as

the result looks believable.

This example still needs some Bump to look realistic, but we‘ll get to that a bit later.

The next parameter is Subdivs:

This setting determines how many samples V-Ray can use to clean up the noise in blurred reflections. Basically: more samples = cleaner

reflections.

Note: Most V-Ray users prefer to use the Adaptive DMC sampler for rendering their images. This means that the actual number of samples

needed for a clean image changes, depending on the DMC settings: 1/4 will need lower values than 1/100. We recommend leaving this value at

the default, 8 subdivs, if the models or materials will be used by other people. Everyone has their own workflow and will adjust it accordingly.

Otherwise, it can get frustrating hunting down a material with a too-high subdiv count that doesn‘t work with a particular render setup.

Reflection Depth & Exit Color

This option sets how many times the reflection is traced before it is converted into the exit color. This helps to speed up the renders by reducing

the amount of calculations V-Ray has to do for reflections. Here‘s an example with exit color set to blue:

The default settings work well most of the time. If you have a lot of mirrors or other reflective objects, you might need to increase the max

depth, though going higher than ~20 isn‘t usually necessary.

If your material has blurry reflections, you can make it render a bit faster without losing quality, by reducing the Max Depth as follows…

Glossiness 0.9-0.99 = max depth 5

Glossiness 0.8-0.89 = max depth 4

Glossiness 0.7-0.79 = max depth 3

Glossiness 0.6-0.69 = max depth 2

Glossiness 0.35-0.59 = max depth 1

Since the reflections are blurred, there will be no negative effects on the image. The values we‘ve provided are more like a rough guide, so you

can adjust them if needed.

Lesser-Known Parameters

That about covers it for the basic Reflection tab– Interpolation is no longer needed, since it‘s much faster and easier to use light cache for glossy

rays in GI settings. Dim distance and Affect channels are only used in some very specific cases (more related to scene optimization, not material

creation).

BRDF

There are a few other options hidden a bit lower, in the BRDF tab and the Options tab.

BRDF is basically a mathematical model that is used to calculate the reflections and specularity for your material. There are three types available

for you to choose from – Blinn, Phong and Ward. Each one has their own specific uses.

As you can see, the main difference is in the way they treat highlights. Phong is the sharpest, Blinn is a bit more blurred, and Ward is much

softer.

There really is no hard and fast rule for which of these to use, but our general recommendation would be to use Ward for metals and anisotropic

materials, and Blinn or Phong (whichever you prefer) for the rest. The only exception is that it is not recommended to switch to Ward for metals,

if the metal is highly polished or has very sharp reflections (like chrome, gold jewelry, etc.).

Anisotropy

Anisotropy is used to simulate stretched out highlights. In the real world, these are caused by elongated micro-scratches that go in the same

direction. Below are a couple of example photos; this effect is seen mostly on brushed metal:

Anisotropy should be set in an interval between -0.99 and 0.99. With values of -1; 0 and 1, it will not do anything.

The effect becomes stronger as the value approaches 1 (or -1). The difference between negative and positive values is the direction of the

stretching. Positive values stretch reflections horizontally (simulates vertical scratch pattern). Negative values stretch the reflection vertically

(simulates horizontal scratch pattern).

You can also rotate the the stretching effect to any angle you want by using the Rotation parameter.

For even more control, you can choose the axis that is used for calculations.

For it to work correctly, Anisotropy needs blurred reflections. If your Reflection glossiness is set very high, the effect will not work.

Just as with other aspects of V-ray, we can use Maps or Textures to drive the Anisotropy parameters as well.

You can use an Anisotropy texture with reduced strength to fine tune the exact amount of imperfection it introduces. Keep in mind that texture

maps only work as positive values, so it‘s best to combine them with positive Anisotropy strength. For example (below), we‘re using Anisotropy

0.6 + 20% of a texture. The result looks a bit more natural than just pure Anisotropy.

Rotation maps can be used to change the direction of the simulated scratches. This is good for creating things like circular patterns or metallic

flakes that reflect light in random directions. Smooth gradients make the rotation gradual, while patches of different colors make the transitions

sharp, with each shade of gray having a different rotation value.

The Options Tab (Reflections)

Before we finish with Reflections, here are a couple more options to consider. Scroll down to the Options tab and take a look at the settings

there:

The outlined options (above) are all affecting the Reflections.

First of all, you should never turn off the Trace Reflections option, since it is essential for a realistic result. If you turn it off and use only the fake

specular highlights, reflections are just that: round, fake highlights, regardless of the shape of the lights or the environment.

Next is Reflect on back side. By default, it is turned off and that‘s fine for most materials, since it helps to cut down on the render time.

However, if you are creating glass or other transparent materials, you have to turn this option ON, otherwise, the result will not look realistic.

And finally, let‘s look at the Energy Preservation mode. The default setting of RGB is physically correct, however, there might be some cases

where the result is hard to predict. For example, a white material with blue reflections (below).

The Reflection amount is subtracted from the Diffuse color. For example, lets take white Diffuse [230;230;230] and blue Reflections [0;0;230].

So, what do we get when we subtract? We get Yellow [230;230;0], and that is exactly what we see when rendering this particular example:

Switch the EPM to Mono and you get a much more predictable result – white Diffuse and blue Reflections.

These types of materials are not common. Change this option only on the rare occasion that you have to create colored Reflections on top of a

bright Diffuse color.

V-Ray Material, Part 3: Refraction

by Calvin Bryson

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 Reflection tab. This week, we‘ll be moving on to:

Refraction

Refraction controls how an object lets light through. For example, if you were to shine a light on an object, how much light would you see

coming through the other side? Unlike Reflection, not all objects are refractive. Some typical examples that use this V-Ray material component

are: glass, water, transparent plastic, crystal, oil, etc.

The amount of Refraction can be controlled by a number, Map, or Texture. It can be grayscale or colored, but it is recommended to stick to

grayscale for more realistic results.

If you are not using Caustics in your scene (most likely you aren‘t), turn on the ―Affect Shadows‖ option to get realistic, transparent shadows.

Otherwise, the shadows will be too dark.

Adding Color To Refraction

So, how do we actually get colored refractions, if it‘s not recommended to use colors in the Refraction amount? We should use the Fog color

option, in this case. It works realistically, since thicker parts of the model will be more colored/darker than the thin parts.

Depending on your object‘s physical size, you might need to adjust the Fog Multiplier Value. Larger objects will look darker than smaller ones

when using the same material.

Use Fog Bias to control the color transitions. Lower values make the color more intense and the transitions sharper, while higher values make

the tinting more weak but even. If you adjust both of these parameters (Fog Multiplier and Fog Bias), you should be able to achieve any effect

you might need.

Refraction Glossiness

Refraction Glossiness simulates a rougher surface, by diffusing the light rays in different directions. Lower values create a rougher look (frosted

or sand-blasted glass, or textured rough plastic), and higher values are for smooth surfaces. Since glossy Refractions are one of the biggest

increases for render times, they are usually used in a smaller range. You probably don‘t need to go lower than 0.7 to achieve the desired look.

You can use a Texture to create a rougher, more realistic look. If the material is still pretty clean, don‘t overdo it and use a map that is mostly

pure white with some darker spots/patches. It‘s usually a good idea to keep the Refraction Glossiness map similar to the reflection glossiness.

Any rougher areas would affect the Reflections and Refractions in a similar way.

Note: As with Reflections, we think it’s best to leave the Subdivs at 8, for the end user (your customer) to adjust for themselves.

Refraction Depth and Exit Color

The Refraction Depth and Exit Color function exactly the same as their Reflection counterparts: bump up the max depth if there are lots of

refractive/reflective objects and bring it down if using blurry Refractions.

Refraction IOR

IOR is a very important parameter to set correctly, in order for your material to look believable. Fortunately, these values have been calculated

for all sorts of materials, so there‘s no need to guess here.

With the Value of 1 (same as air), the rays of light are going straight through the object without any distortion. As you raise the number higher,

the rays get distorted more and more.

Acetone 1.36

Agate 1.544

Air 1.0002926

Alcohol 1.329

Amber 1.546

Amethyst 1.544

Crystal 2.00

Diamond 2.417

Emerald 1.576

Ethanol 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

Ice 1.309

Jade, Nephrite 1.610

Jadeite 1.665

Methanol 1.329

Moonstone, Albite 1.535

Nylon 1.53

Onyx 1.486

Opal 1.450

Plastic 1.460

Plexiglas 1.50

Polystyrene 1.55

Quartz 1.544

Quartz, Fused 1.45843

Rock Salt 1.544

Ruby 1.760

Sapphire 1.760

Tiger eye 1.544

Topaz 1.620

Tourmaline 1.624

Turpentine 1.472

Turquoise 1.610

Water 35′C (Room temp) 1.33

Zirconia, Cubic 2.170

Breaking the Rules

Technically, both the Reflection and Refraction IOR should be the same, but sometimes, you might want to unlock them for artistic reasons. This

trick is used when glass or transparent plastic material just seems to lack reflections. In this case, bumping up the Reflection IOR can help in

bringing out those reflections. It‘s also useful when you want to create a more even distribution of the reflections, without increasing their

intensity.

Dispersion

Dispersion controls how the light is split up into different colors when passing through an object. A classic example of this would be a ray of

light going through a prism, creating a rainbow effect. Most glass and other refractive materials show at least a little bit of dispersion. The exact

amount is controlled by the Abbe number. The basic idea is, as the Abbe number goes lower, the dispersion effect increases. It‘s easy to overdo

it, but it should actually be pretty subtle.

Since it is quite slow to render, most of the time you can get by without dispersion. We only suggest using it for close-up studio renders of things

like jewellery, glass, or crystals.

Refraction & Alpha Channels

Finally, a quick tip to remember: for Refractive objects, it is generally a good idea to set the ―Affect Channels‖ to ―All Channels.‖ This way,

your alpha channel will not be solid white, but will be adjusted, depending on the transparency of the object. This is very useful in post-

production.

V-Ray Material, Part 4: Translucency & Bump

by Calvin Bryson

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.

V-Ray Material, Part 5: Workflow

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.

Diffuse

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.

Reflections

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.

Remember:

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.

V-Ray FastSSS2 Material, Part 1

by Calvin Bryson

The following is an in-depth guide to the regular V-Ray Blend Material. In this series, we will cover the theory behind many of the features of

the material. We‘ll also show specific examples of settings and give you some tricks to use. While the images used are from 3ds Max, the same

concepts and settings can be used for V-Ray for Maya. Currently, the SSS materials in V-Ray for C4D behave differently, so this tutorial will

not be as valuable for C4D users.

The V-Ray FastSSS2 Material is designed for creating translucent materials (ones that scatter the light inside the object). Some common

examples are: skin, marble, wax, milk, etc.

Compared to the ―translucency‖ option in the regular V-Ray Material, it has a far better sub-surface scattering model (SSS). It is faster and

much more advanced. For this reason, it‘s preferable to use the FastSSS2 Material whenever you need to make a translucent shader.

Settings

Since this material works in a slightly different way than other V-Ray Materials, let‘s look at its settings and some examples of how they work.

Presets

You‘ll notice that there are a few presets. These are pre-defined materials that you can choose from a drop-down menu and quickly use in your

scene.

They do need to be customized with your own maps to look their best (colors, bump, reflection, gloss). So look at them as more of a starting

point than a finished material. Perhaps the only ones that are good ―as is,‖ would be the Milk presets, since it‘s a liquid and you may not need

any maps.

Prepass Rate

Next, let‘s look at the Prepass Rate value. FastSSS2 calculates the distribution of light within an object using something similar to the Irradiance

map, so this parameter sets how detailed we want this calculation to be. For most cases, you can leave it at -1 for optimal speed/quality; for test

renders and objects without small details, bring it down to -3 or -2; but for very detailed objects that show some problem areas, try bringing it up

to 0 ~ 1.

Scale

Scale controls the depth of the SSS effect. Since this material uses real world units to calculate the final result (you can set the scatter depth in

cm a bit further down), this is an easy way to quickly turn up or down the depth. Quite simply, Scale 5 gives us Scatter Depth*5, etc.

IOR

IOR is the same old Index of Refraction that we are so familiar with. Here are some general guidelines:

Water based materials (Milk, Juice, Skin, etc.): set it to 1.333

Stone/Marble: 1.5~1.6 works best

Glass: 1.6~1.9

Plastics: 1.45~2.45. This parameter affects both (the Refractions [SSS] and Reflections). There is no way to unlink them currently.

Options

Before we proceed with the Diffuse and SSS layers (in the next part of this series), let‘s check out Options. The most important things here to

adjust are the Single Scatter type, Subdivs and Depth.

Single Scatter

There are 3 types of Single Scatter you can use: Simple, Solid and Refractive. These are all used for specific types of materials.

1. Simple is the quickest to render but is also the least accurate. It‘s great if the material doesn‘t let in a lot of light, just a little bit (skin,

plastic).

2. Solid mode is best to use for materials that let in a lot of light, but at the same time are quite opaque, like translucent stone, milk, or wax.

3. Refractive mode is for those materials that also have visible refractions and you can see through them relatively well- things like foggy

glass, murky water, etc. This mode also makes the shadows transparent.

Subdivs & Refraction Depth

Subdivs and Refraction depth work much like regular V-Ray materials. Increasing subdivs cleans up the noise in the translucent areas; refraction

depth controls how much the light bounces around. In general, you can leave these settings at their default values. If they need to be optimized

for a particular scene (say, if an object is very refractive and not very opaque), you may try increasing the depth to be sure there are enough

bounces to make it look realistic.

Most of the time, the rest of the settings in this section work just fine, as they are. If the render appears too blotchy, you can play around with the

prepass blur value. Higher values will blur the scattered light more, though decreases accuracy.

V-Ray FastSSS2 Material, Part 2

The following is an in-depth guide to the regular V-Ray Blend Material. In this series, we will cover the theory behind many of the features of

the material. We‘ll also show specific examples of settings and give you some tricks to use. While the images used are from 3ds Max, the same

concepts and settings can be used for V-Ray for Maya. Currently, the SSS materials in V-Ray for C4D behave differently, so this tutorial will

not be as valuable for C4D users.

Diffuse and SSS Layers

This is the most important (and, generally, the most confusing) part of the FastSSS2 material. The problem is, there are many different colors to

set up and they all seem to affect one another in some way, so it can be a bit difficult to work non-destructively.

In this tutorial, we‘ll attempt to de-mystify these settings so they‘re a bit easier to work with.

Diffuse Color, Diffuse Amount, & Sub Surface Color

Let‘s start with the Diffuse and SubSurface colors: essentially, they set up the inner and outer color of the object and allow you to set exactly

how much each one affects the final material. To demonstrate how this works, we‘ve set up the Diffuse to be a pure blue, while SubSurface is

set to a pure red. Look how everything changes as we adjust the Diffuse Amount value:

At 0, only the SSS layer is visible, while at 1, only the Diffuse is visible, with no light scattering inside of the object. Everything in-between is a

mix of the two.

Overall Color

Now, we‘ll bring the Overall Color into the equation. This acts as a filter for both the Diffuse and Subsurface and it affects how much of the set

color is to be seen in the actual material. Pure white [255;255;255] lets through 100%, while medium grey [128;128;128] lets through 50%.

This sounds simple, but it also works the same way with colors: pure red Overall color [255;0;0] only shows the red channel of both Diffuse and

SubSurface colors. In this case, it is pure black, since neither of the colors have any red channel value. Basically, the RGB value of Overall color

determines exactly what percentage of each channel is visible in the other two colors.

We recommend sticking to grayscale values or grayscale textures in this slot. Otherwise, it is very hard to predict the resulting look. It‘s not

‗intuitive,‖ but mathematical. However, a simple B&W map can be good way to make everything a bit more interesting, without getting

unexpected colors.

Scatter Color

Finally, there‘s one other color to adjust: Scatter Color. This defines the color of the scattered light rays once they enter the surface of the object.

That means it also affects the intensity of the scattered light, so if you set it to black, the light turns black and no scattering is going on.

Again, this one is a bit tricky to use if you use colors instead of grayscale values, since it interacts with the SubSurface color in a mathematical

way. We‘re not 100% sure of the exact formula behind it, so your best bet is trial and error- try first to adjust the lightness of this color and then

tweak the hue until you get the exact look you want. Usually, the Subsurface hue and Scatter color hue should be pretty close.

Scatter Radius

Scatter Radius allows you to set an exact depth to which the light rays can penetrate the surface. If you need to be sure the result is accurate, take

care to keep the Scale at 1 and make sure the object‘s XForm is reset.

Phase Function

We‘re almost done! The last parameter to adjust here is the Scatter Phase. It can be set from -1 to +1 and it controls the way light rays travel

within the object‘s surface. Zero (0) scatters the rays in all directions equally; positive values focus the light mostly forward; and negative values

make most of the rays go backwards. As a general rule, water-based materials (skin, juice, milk) tend to scatter the rays forward, while hard

materials (marble, glass) tend to scatter them backwards.

V-Ray Fast SSS2 Material, Part 3

The following is an in-depth guide to the regular V-Ray Blend Material. In this series, we will cover the theory behind many of the features of

the material. We‘ll also show specific examples of settings and give you some tricks to use. While the images used are from 3ds Max, the same

concepts and settings can be used for V-Ray for Maya. Currently, the SSS materials in V-Ray for C4D behave differently, so this tutorial will

not be as valuable for C4D users.

This week, we‘re concluding this series of TurboTips with information on the Specular Layer; a few more settings for the FastSSS2 Material;

and a sample workflow to help you put it all together.

Specular Layer

If you are familiar with the regular V-ray Material, this section will be very familiar to you. Basically, the Specular Layer is the same as

Reflection, it‘s just named differently. For physically accurate results, you must turn on the Trace Reflections option; otherwise, only fake

speculars will be used.

There is no way to unlink the Reflection IOR from the base IOR of the FastSSS2 material. Most of the time, this shouldn‘t be a problem, since

that is the physically correct way to do it, anyway.

The Rest of the Settings

With the exception of the Diffuse and SSS layers, most of the FastSSS2 material is very similar to the regular V-ray Material, so all the same

principles apply. You can also use maps in many of the slots that initially seem to support only colors (no little squares to set up maps next to

color slots). Just scroll down to the Maps section and plug them in there.

Workflow Example

Let‘s take everything we‘ve learned and create a translucent material from a reference photo. We‘ll attempt to make something similar to this

jade:

Start by looking up the IOR for jade. Turns out, it is almost the same as glass: 1.61. Let‘s set it up on our material:

Next, we need to determine what type of scattering we need. In the reference photo, it looks like the material is a bit refractive (you can see

through the thinnest areas). Let‘s set up the Single Scatter mode to Raytraced (Refractive).

Next, we want to set up the basic look for the Reflections. Go to the Specular layer and make sure that the ―Trace Reflections‖ option is on. It

looks like the reflections are very glossy on this highly polished surface, so we‘ll set up the Glossiness at 0.92. We also made the Specular color

a bit darker [220;220;220] to make the reflections a bit more realistic.

Let‘s see what we‘ve got so far…

Now we are ready to move to the most important step: the Diffuse and SSS layer. We‘ll start by setting up the Phase function to -0.8, since this

is a stone type material. We‘ll also bring up the Scatter Radius, since it looks like the light is scattered pretty deep within the object. Let‘s try

something like 30 cm.

At this stage, it looks like the Radius is a bit too large, but that‘s ok. We will use a Noise map in the Radius slot, which will be multiplied by this

same value. So if we have Radius at 30cm and a medium grey map [128;128;128] in the slot, the actual radius will be 30*0.5=15cm. This gives

the material a quality where some areas appear less translucent while some are more translucent.

Here‘s the noise map setup…

And here is the resulting render…

Now we need to set up the colors. We‘ll start by setting up this texture in the SubSurface color slot…

Now let‘s tone the Scatter color. We want it to be more blue in the green areas, and more yellow in the yellow areas. This image doesn‘t need to

be too detailed, so we blurred it. This will also help with the foggy look.

The results already look pretty good. We just need to add a few small details to make it perfect.

We‘ll use this gray texture in the Overall color slot to add some slightly dirtier looking patches to the object.

A variation of this texture can also be used in Spec color, Gloss and Bump slots to bring us to the finished material.

The material is finished. In this case, we did not need a Diffuse layer, since the outer/inner colors of the jade material appear to be identical.

As you can see, the idea is to take care of the technical details first (IOR, scatter type, phase, etc.), then tweak the artistic parts (colors/maps).

V-Ray Blend Material, Part 1

The following is an in-depth guide to the regular V-Ray Blend Material. It will cover the theory behind many of the features of this material,

and will also provide specific examples of settings, as well as tricks to use. While the images used are from 3ds Max, the same concepts and

settings can be used for V-Ray for Maya. The information covered here will be generally useful for V-Ray for C4D, but the blend material acts

quite differently in C4D.

Introduction

The V-Ray Blend Material could be best described as a utility material. It does not have any shading options, so it combines multiple other

shaders in different ways.

The layout is simple: you have a Base material and nine Coat materials. In fact, they all function in the same way (similarly to layers in

Photoshop), so you have a ten-layer stack. Each layer after Base has a Blend amount, Color, and Map.

Blends can be as complex as you want them to be. Since you‘re not limited to the ten slots, you can always add another blend in the last layer

slot and keep piling on layers. However, in the real world, this isn‘t the most practical way to do things. Each new layer makes the render slower,

since V-ray has to calculate all the materials in the blend, and then blend them together. This means you could easily bog down your render

times if you get too carried away.

Most of the time, 4-5 layers should be the absolute maximum to use, with 2-3 being the norm. It‘s also easier to manage the shader with fewer

layers.

Let’s see how they work.

We‘ve set up a Red material in the Base slot and a Blue material in the first Coat slot. You can see how the Blend amount color affects how

much of the second layer is visible. It‘s a simple opacity scale: black makes the coat invisible, and white makes only the coat visible. Everything

in between is a mix of the two.

Of course, you can also use a map in the Blend amount slot. The map needs to be grayscale and the Gamma, when loading the image, should be

set at 1.0 for correct results.

Here‘s an example with a black and white map in the slot.

You can also mix the Map with the Blend amount color, using this numerical value. At 100, it only uses the map; at 70, it uses 70% of the map;

and at 30, 30% of the color, etc. This is great when you need to fine-tune the exact amount of blending, without changing the texture itself.

So, what about adding another coat layer?

Once you add another material to the list, everything above it is combined and treated as a single base layer (exactly as in Photoshop, except the

layer list is reversed- from the top, down).

If we add a Green layer to our Red and Blue, the result is not Red+Blue+Green, it is Purple+Green, since the first two layers get mixed at 50%,

and the result is mixed at 50% with the next layer.

Lastly, the Additive mode check box always needs to be turned OFF for physically correct renderings. It is only there to mimic the functionality

of a regular 3ds max Blend Material, but should not be used if you want believable shaders.

V-Ray Blend Material, Part 2

by Calvin Bryson

Last week, we gave you a little overview of the V-Ray Blend Material. This week, we have an important question:

When should I use Blend over other types of materials?

1. When there are layered materials, where the base and coat can be seen clearly as different materials.

In the example below, you can see that the wood has a completely different reflection/highlight pattern than the glossy lacquer layer on top.

2. When an object has radically different surface properties in large areas.

In this example photo, it‘s easier to create two different shaders for galvanized metal and rust and blend them together, instead of trying to do it

all in one material.

3. When the object needs a specific shading effect that is not possible with a simple material.

A good example would be worn and/or slightly dirty metal that has glossy and blurred reflections at the same time.

4. When the shader needs to be easily and quickly modified.

Let‘s say you have a rusty, painted metal material with three different types of surfaces: metal, paint, and rust. Theoretically, it would be possible

to build elaborate mix maps and custom-painted textures to create all these effects in a single material… but imagine if you need to change the

rust pattern. “Oh, yeah, the material looks great, just make it a bit less rusty!” What a nightmare! You would have to go through all the maps

and adjust them, one by one, to make this ―small‖ change.

Now imagine that you have 3-layered blend instead (Metal, Paint and Rust layers). Everything is controlled by two simple b&w masks that can

be adjusted quickly and easily. This saves a lot of time and is far less frustrating.

V-Ray Blend Material, Part 3

The following is part of our in-depth guide to the regular V-Ray Blend Material. It will cover the theory behind many of the features of this

material, and will also provide specific examples of settings, as well as tricks to use. While the images used are from 3ds Max, the same

concepts and settings can be used for V-Ray for Maya. The information covered here will be generally useful for V-Ray for C4D, but the blend

material acts quite differently in C4D.

Examples & Common Issues with V-Ray Blend Material

Blending Two Different Materials

This is perhaps the most common use of V-ray Blend. Imagine that you have two radically different materials that are assigned to the same

object; for example, dirt spots on glass. Glass is refractive and reflective. Dirt has very weak and blurred reflections and is not refractive at all.

So, it makes sense to create two materials and just blend them with a black and white map.

Here‘s the glass material…

And here is the dirt material…

Now, we simply plug them into the Base and Coat slots, and assign a texture to the Blend Amount…

That‘s it! The result looks good and you can always swap the Blend Amount texture for something different to change the dirt distribution.

Refractive layers

Most of the time, it‘s fairly easy and intuitive to break down the Blend into multiple simple materials. The way they look is obvious: metal is

metal, wood is wood, etc. The only exception is with Refractive layers (things like lacquer, clear coat, epoxy, etc.). While they‘re refractive in

the real world, you should not make them refractive in V-ray, since it forms a strange and incorrect result.

Let‘s say we have a green plastic material, to which we want to add a clear coat reflection (imagine it‘s been dipped in lacquer).

The way to approach it is perhaps counter-intuitive, but works very well: set up a V-ray Material with black diffuse and 255 white reflections

(fresnel off) in the Coat material slot.

For the Blend amount, use a Falloff map set to Fresnel with 1.5 IOR (acrylic). Now, lower the white color slightly, to something like 215.

And here is how the resulting shader looks. The effect is exactly what we were trying to achieve.

Bump

One of the most common problems with V-ray Blend Material is Bump. To achieve a realistic look, the same map should be featured in all the

layers, especially if the mask is very high-contrast with sharp borders around patterns.

This scratched paint material has bump in white layer only. It doesn‘t look that great.

In this version, we‘ve added the same bump map to the Paint material as well.

Looks better, but what if you also want to add an ‗orange peel‘ effect? If you need additional bump effects, you have to change the map type in

that particular layer to composite and instance the common texture in there. Now you can composite other maps on top of it, while still keeping a

the common bump as well.

In future V-Ray versions (v3 and possibly 2.5), this can be made much simpler by using a V-Ray Bump Material. This functionality will allow

you to add common bump to the whole material, on top of each layers existing bump.

Glossiness blend

Let‘s see how we can create an advanced shader that currently is impossible with regular V-ray Material. The effect we‘re looking for is a ‗tail‘

for the Reflections.

First, we‘ll set up a basic metal material in the base slot.

Now, let‘s copy the material to the next two coat slots and gradually reduce the Glossiness value.

Finally, we just need to adjust the Blend Amount color for both coat slots. Usually, the further the reflections are blurred, the less we want the

layer to be visible. Reduce the second coat amount more.

And here is the result…

To make it more interesting, you can use texture instead of color in the Blend Amount slots. Here, we‘re using a simple scratch-map…