VRay Training Manual for RHINO

V-Ray for Rhino 1.0

www.asgvis.com

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Installing V-Ray for Rhino1.0

Activating V-Ray for Rhino 1.0

V-Ray for Rhino Toolbar

V-Ray for Rhino Render Options

V-Ray for Rhino Material Editor

? ? ? ? ? V-Ray for Rhino? ? ? ?

Open V-Ray for Rhino Toolbar

Open V-Ray for Rhino Render Options

Load and Save Render Options

V-Ray Material Editor

Diffuse

How to add new material

How to duplicate a material

How to change the name of a material

How to remove material

Others

Use Material

Add Lights

The Characteristics of Rectangular LightSize does matter

Shadow changes according to the size

Impacts on reflective objects due to Visible and Invisible Rectangular Light

Double Sided Option

Material: Reflection MaterialAdding Reflection layer

Fresnel Reflections Explained

Reflection and Highlight

Other characteristics of reflectivityReflection Glossiness

Reflection Filter

Material: Transparent MaterialAdd transparent layer

Transparency percentage of material

The color of transparent material

Fog Settings Explained

The Refraction of transparent material

The Glossiness of transparent material

The shadow of transparent material

Double-sided material

Material: Transparent MaterialAdd Emissive Layer

Adjust the Intensity

Adjust the Color

Texture Editor Setting

Material: Texture Mapping ..... 041

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Table of Contents

Texture Mapping

UI types and adjustment

Material: Bump MapAdd Bump map

Material: Transparency MappingWhat's Transparency Mapping?

The logic of Transparency map

Another way of using Transparency map

Other uses of transparency

Illumination: Environmental LightingLet's do a test first

Interior or Exterior?

Techniques to adjust the Brightness

HDR Environment light

Bitmap Environment light source

Environment light source for semi-open space

Issue of irradiant light

Render EnginePrimary Engine

Secondary Engine

Primary Engine: Irradiance Map

Primary Engine: Quasi Monte-Carlo

Secondary Engine: Light Cache

Depth of FieldWhat is Depth of Field?

How to find out the current setting of focus distance of the camera?Size of Aperture

Change Focal Distance

Caustic EffectWhat are Caustics?

Brightness

Liquid inside of transparent GlassStrange Effects

Adjusting the CameraRotate the camera

Adjusting the lens

Lighting Dialog Box

Color MappingThe Function of Color Mapping

Types of Color Mapping

Adaptive Subdivisions ControlAdaptive Subdivisions Sampler

Fixed Rate Sampler

Adaptive QMC Sampler

Resolution of an ImageImage size setting

File saving set up

V-Ray frame BufferRender image window tool box

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V-Ray for Rhino 1.0004

6.Installation complete5. Installing

4.Click install to begin installation3. Choose complete setup type, click next

2.License Agreement, click next to continue1.Make sure Rhino is not running then install

VRayforRhino3_1.0.exe from the CD

Installing V-Ray for Rhino 1.0

V-Ray for Rhino 1.0 005

6.The activation for V-Ray for Rhino is now

complete. You will not need to activate it 5. Activating usually takes several seconds

to finish

4. Enter your serial number then click next.

It will start activating3.If you already have a serial number, you

can select the other option, “I have a serial

number and I want to activate V-Ray for

2.The InstallShield Wizard will ask you to

select one of the options. If you haven't

purchased V-Ray for Rhino, you can choose

“I want to evaluate V-Ray for Rhino, but I do

not want to activate at this time

1. After finishing the installation, run the Rhino program. Click Render on the tool bar to choose the Current Renderer as V-Ray for

Activating V-Ray for Rhino 1.0


V-Ray for Rhino toolbar consists of three major tools. They are VRay Materials, VRay Options and

Show VRay Frame Buffer. You can also find them from the tab above

4. This is what you will see after you

insert the toolbar3. Select VRay for Rhino and close the

window

2. Find Vrayforrhino.tb and open it1. From Toolbar Layout window, select Open

under File

Open V-Ray for Rhino Toolbar

V-Ray for Rhino 's Toolbar wil l not open automatically. User must open and insert

it onto the screen. Use Tools>Toolbar Layout, click File>Open…, under C:\Program Files\Rhinoceros

3.0\Plugins\Vrayforrhino\Misc, find VRayforRhino.tb and insert it

V-Ray for Rhino Toolbar

V-Ray for Rhino 1.0 007http://www.doschdesign.com

以上HDR以及著色圖片由Dosch Design公司授權提供給本手冊使用

? ? ? ? ? V-Ray for Rhino? ? ? ?

http://www.aversis.be/index.htm


Open There are 3 cups and a ground plane in the file. None of the objects have any

materials assigned to them and there is no light in the scene. Click the blue render icon and you will get this

gray tone image without changing any setting in the V-Ray Options.

“Cups-Original.3dm”.

Save and load Option settings

There are many Options settings in V-Ray for Rhino. Users can save their preferred settings, or save different

files according to different scenes, different render quality setting, or different GI engines.

Use File>Save to save Options settings. It will be saved as .visopt file format. You can save any Options scheme

so that they can be loaded to another scene later. Also, when you save your Rhino file all changes in V-Ray

Options setting will also be saved.

Use File>Load to load saved .visopt Options files. It will then replace the current setting. Use Restore Defaults

to restore all settings in Options.

Open V-Ray for Rhino - - Render Options

The V-Ray for Rhino Options controls all parameters for

V-Ray. You can open this Render Options from the menu

bar above or click directly on the V-Ray Options from

the toolbar

V-Ray for Rhino Render Options


1. Global Switches：

2. Indirect Illumination：

3. Environment：

Uncheck Hidden Lights and Default Lights under the Lighting

section.

Hidden Lights refers to any lights that are either hidden or on a

hidden layer. By unchecking the Hidden Lights box, those

hidden lights will be disregarded by V-Ray. To prevent any

hidden lights from affecting the final render output, we

recommend you uncheck the Hidden Lights.

Default Lights are the lights that Rhino uses to illuminate the

model within the viewport. Users can not see or edit these

lights from the scene. If one uncheck the Default Lights and

does not check the GI below, the render will turn out totally

black.

Check the On under the GI section. That turns the Indirect

Illumination on, also called the Global Illumination. We will

explain those green dot items more later.

Check the boxes before GI and Background.

These settings controls the appearance and brightness of the

Environment, and therefore, the main illumination of the

scene.

Please adjust those three items then render. You will get the

image with Global Illumination. Compare to the image without

Global Illumination, you can see the objects don't have dark

shadow because the whole environment is now providing the

illumination for the scene.

Open V-Ray Options window and pull down the Global

Switches, Environment and Indirect Illumination tabs as


By default objects which have not been assigned materials receive Rhino’s standard white material.

To assign materials to an object and make adjustments, we need to open the Properties tab

. Press Ctrl+A to select all the objects in the scene then click the Object under the Properties

window to select material. The objects are assigned materials by layers by default. Click Plug-in,

there will show three tabs: Browse, Edit and Create.

Two ways to assign materials in V-Ray

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The image has a blue tone is because the default environment color of V-Ray is set in light blue(RGB

204, 224, 225). Please click the color box under GI to edit the color. Change the Sat from 51 to 5.

The color is changed to be almost white(RGB 250, 252,

255). Click OK to accept the changes and then click

Render. The image color becomes very close to white

like the image on the right.


Another way to assign materials is through material editor. Please refer to page 13

3. Now the objects are applied with materials, so the Edit button is selectable. You can click on the

Edit button to open the Material Editor to modify the materials

2. Click the Browse button, in the choose

material window, select

Default_VRay_Material, then click apply


Click the Update preview button to update the preview image of the selected material. This

preview is not updated in real time, therefore, it must be manually updated.

V-Ray Material EditorV-Ray for Rhino's Material Editor has three parts:

. Material Workspace shows all the scene materials. Right clicking on different elements in the

workspace will provide added functions within the Material Editor.

. Material Preview, the Update Preview button allows you to preview the adjusted materials.

. Options for material control. This is where parameters for each material is modified.

A

B

C

Material editor can be pulled out from the icon under VRay for Rhino tool box, from Material Editor

from V-Ray tab, or by clicking the Edit button in Properties window.

Material Editor in V-Ray for Rhino


How to add new material:

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Right click on Scene Material, select Add new material.

. Right click on Scene Material, select Import new material to import a saved material file.

. In the Properties window, click on Create button to add a new material

Diffuse:

Color：used to apply color on material. The m box on the right is used to apply a texture map to an

object

Transparency: used to adjust the color transparency. Black is opaque. White is transparent.


How to remove material:

Right click on the name of the material you wish to delete, and select remove. If the material being

removed is applied to the objects in the scene, V-Ray will show a pop-up window to ensure that you

want to remove it.

How to change the name of a material:Right click on the name of the material you wish to change, and select Rename. The name of the

material can not have space or numbers in the first digit.

How to duplicate a material

Under Material Workplace, right click on the material you wish to duplicate, and select Duplicate.

This is another way to add a new material


Rhino’s Undo does not affect V-Ray for Rhino Options or

Material Changes

Purge unused materials: Right click on Scene

Materials to select purge unused materials to

remove materials which are not applied on the

scene objects.

Any materials under the Scene

Materials can be applied to

objects by c l icking Browse

under Properties.

Others:Right click on the material you wish to export, and select export to export this material. The file

format is .vismat, the file is 1 KB. This file can be imported or sent to other users later on

By Right-Clicking on a Material you can also:

. Select Objects by materials: select the objects in the scene with this material

. Apply materials to object(s): Apply this material to selected objects in the scene.

. Apply materials to layer(s): Apply this material to selected layers. All the objects in the same

layer will be applied with this material

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V-Ray automatically updates the changes of materials to the objects. It is not necessa ry to apply materials again.

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. Select Diffuse to enter color selections .V-Ray's default color is R-127, G127, B127. Change the

color to light gray as: R230, G230, B230 then exit

. Right click on Ground material. Select Duplicate and rename as Cup-Yellow.

.Deselect the ground plane by holding CTRL and clicking on it. Then go back to Material Editor

and right click on Cup_Yellow and select Apply material to objects

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02

. Open Select all the objects. Under the Properties window, select material,

check plug-in and click Create to add a new material. Material Editor will show a new material

named DefaultMaterial under Scene Material.

. Rename this new material as Ground

Cups - GI.3dm

The file has already set GI environment light and background color. Hidden Lights and Default Lights

are off. Other options are kept at their default settings.

Use Material


13. Create a new material and name it

Cup_White. Change the diffuse color to white.

Select all of the objects on the layer named

Inner Cup and apply the material to those

objects

12. Render and see if you can get the same

result as the image below.

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. Duplicate the Cup_Yellow material and rename it as Cup_Green. Repeat 06 and set the value to

R127, G255, B178 and exit.

. Apply this Cup_Green material to the bottom right cup

. Duplicate the Cup_Green and rename it as Cup_Orange. Repeat 06 again and set the value to

R255, G94, and B0 this time.

. Select the cup on top and apply the Cup_Orange

material to it.

06

07

. Click on Diffuse and change the color to R255, G191, B0 (yellow) and exit

.Render and see if you get the same result like the image on the right.


05 Select this Rectangular light you just

created.

04. To complete creating the light, make your

third left click on the top left of the scene,

approximately the same distance as between

first and second spots.

03. Start from bottom left and make your

second left click to the bottom right of the

scene.

02.From Top view, follow the steps below to

create Rectangular Light in the scene

We didn't add any lights to the scene, however, the render turned out pretty good already. The

shadow is kind of smooth because we used GI as the only light source. So we still need to add more

lights in order to have more depth to the image

. Right click and hold on the Spot Light icon from toolbar above. A secondary toolbar will pop out,

select the fourth one from the left (Create Rectangular Light)

01

Add Lights


11. Hit Render again and you will get a

much better result like the image below10. When we uncheck

No Decay, the default

s e t t i n g o f t h e

intensity is set to 1.

P lease change the

Multiplier from 1 to 4.

09. Uncheck the No Decay. This will make the distance between the light and

objects being considered while rendering. That means the object further

away from the light will recieve less light and become darker. To make the

object brighter, you can either increase the intensity of the light or move the

light closer to the object

08. Select the

Rectangular Light.

Under the Properties,

click on Object and

select Light.

07. Render it and you will get a very bright

image like the one below. That's because the V-

Ray's default setting of the Rectangular Light is

set to No Decay. Please follow the steps below

to adjust it

06.Go to the Front view. Left click and hold

right on top of the light and drag it to the top,

approximately 5X of the height of the cup


Please see the images below for comparison of different intensities.


The Rectangular Light plays a very important role in V-Ray. Despite its ease of use, it also produces

a smoother final result. Unlike the Spot Light, Rectangular Light doesn't have the worry about the

angle of the light. Rectangular light also allows reflective material to bounce the light around the

scene because light is emitted from an area which has many points, as opposed to other lights which

only emit light from a single point. Below are some important characteristics about Rectangular

Light.

See images below and you will find the size of the Rectangular Light does affect its intensity. Size does matter

The Characteristics of the Rectangular Light

Shadow changes according to sizeLarger Rectangular light spreads light to a larger area, so the shadow is not as clear as you will get

from a smaller rectangular light. Compare the images below and you will see the differences

between two different light sizes. The one on the left is rendered with a smaller light.

If you want to have a stronger shadow, we do not recommend creating a small, high intensity light. It

is better to use a different light type.


1

You can tell the direction of the light from the short line on one side of the

Rectangular Light. Rotate the light and you can change the direction of the

light.

The Double Sided option can turn the light direction from one side to both

side of the light. Just like creating two lights with opposite directions. Move

the light away from the floor or wall to avoid any black out area.

The Double Sided option usually used when rendering a large interior scene. It helps to light the

space without using a lot of lights. There will be more discussion about lighting and environments

later on.

The default has the Double Sided option unchecked. Of course, if you check the Invisible option,

you will not see the light in those three images on the next page.

Impacts on reflective objects due to Visible and Invisible Rectangular Light

There is an Invisible option in Rectangular Light. It allows you to determine whether the light will

be visible or invisible in the image. See images below. The one on the left has the Invisible option

unchecked so the light appeared in the image. When a reflective material is applied to the object,

the light will also be in the object’s reflections. The image on the right has the Invisible option

checked. Thus, you don't see the light in the image or on the object with reflective material applied

to it

The default setting for Rectangular Light has the Invisible option unchecked. If you see any unusual

dark shadow in your rendered image, please check if your camera is blocked by the Rectangular


Pay attention to the size, location and intensity of the light because it will affect the brightness and shadow

clarity of your final result.

If the light is placed too far and is not bright enough, you can either increase the intensity or size of the light. On

the other hand, you can lower the intensity or reduce the size of the light if you place the light too close. You

need to keep adjusting the size, location and the intensity of the rectangular light in order to get a good lighting

result.

Other kinds of light work the same way. Different shapes, colors and materials of the objects, and different light

types will all affect the image, therefore, the quantity, size, and location of the light need to be changed

according to different scene. To get a better result, we recommend you change only one value at a time to see

how it turns out after rendering until you get the image you want.

3. When Double Sided option is checked2. Light direction towards the right side1. Light direction towards the left side


4. Click on the “m” next to the reflection color to

add a reflection map.

3. Click on Update Preview button to see the changes. The red ball becomes composed with black-

and-white squares, which is because the default is set to be completely reflective. An object with

this material works like a mirror that reflects the other object next to it. This kind of reflection is

usually applied to mirror or metal, such as smooth stainless steel.

2. To remove a layer, right click on the layer

you wish to remove then select remove

This section is about how to add and edit reflective properties of materials. Please click on the red

cup in the scene. Click on Edit button under Material selections in propertieis

.Click on the “+” next to Cup_Orange under Scene Materials to pull out all the layers. Right click

on Reflection Layer. Select “Add new layer “to add a new reflection layer for this material. There

will show Reflection under the material control section, as it shows on the right.

Adding a Reflection layer

1

Materials: Reflection


7.Below image rendered with Fresnel IOR

set to 2.5, it has more reflection and

looks more like a metal texture now. The

cup has some black reflection due to the

default setting of the background color is

black. Under V-Ray Option, change the

color under Environment>Background to

white and see what you will get

6. Please use the same method and apply

Fresnel to other colors and render it.

6. Click on the Update Preview again

The Material now has reflection quality with the same color on it. Notice the “m” on the right side

of the Reflection is now changed to “M”. That means there is a Map applied to that parameter

5. Scroll down the box next to Type, and then select Fresnel. Fresnel IOR is to control the angle at

which surfaces begin reflecting. Keep the value at the default level of 1.55, then click Apply.


Wondering why V-Ray rendering engine doesn't have the highlight option built into it as previous

rendering engine Flamingo? The truth is that the highlight is created by reflecting a very bright

object or light in the scene. It also called lightsource.

Some rendering engines use Highlight to create lightsource if there isn't any lightsource in the

scene. But current V-Ray for Rhino version does not support this option. So you must create

Rectangular Light or other self lit object as a lightsource for the scene.

Reflection and Highlights?

Fresnel Reflections Explained

Fresnel Reflection is a naturally occurring phenomenon that states that an object becomes more reflective the

greater the angle at which it is seen(think of looking at a window from straight ahead as opposed to an angle).

Through manipulating the Index of Refraction(IOR) the reflective characteristics of an object can be changed.

A lower IOR means that a larger angle is needed between the observer and the object before the object begins

reflecting. A higher IOR means that a smaller angle is need, which in turn causes the object to reflect sooner.

To maintain physical correctness of your renderings it is advised to have the IOR of an object correspond to its

real IOR.

Below are six rendered samples with different Fresnel IOR. The last one is rendered with full reflection to

create chrome material.

Reflection GlossinessYou don't always get clear reflection from reflective

material. Objects like matte finish metal, wood and some

plastic materials do not reflect their environment clearly

due to their uneven surfaces. This is because the uneven

surfaces create many reflecting angles for light to bounce around. So the reflections are not as

sharp if compared to reflections from smoother surfaces. The best way to create this kind of

rendering quality is playing around the Reflection Glossiness parameter under Reflection.

By Default the Reflection Glossiness is set to 1, which is characteristic of a perfectly smooth

surface. The lower the Highlight Glossiness is the more matte the material will be, but along with

that goes longer render times. Same goes to the highlight Glossiness.

Every object has certain degree of reflection. Some are very strong, and some are weak. But this

doesn't mean we have to apply reflection to every single object in the scene because that will

increase your rendering time significantlly.


0.6

0.7

0.8

0.9

1.0

2.72.42.11.81.51.2

Re

flectio

n G

lossin

ess

Fresnel IOR

Below are results from combinations of various intensities of Reflection Glossiness and Fresnel IOR.

Hope these images will help you create your ideal plastic and metal materials.

Other characteristics of reflectivity


Reflection Filter

There is a white color (default) Filter located to the right of the Reflection. This is used to

differentiate plastic and metal materials. When creating a metal reflection, set the Filter color to

a brighter color of the diffuse color. When creating a plastic reflection, keep the default setting of

white color. Of course you can set it to any color to mimic the filtered lenses.

Samples of less Reflection Glossiness

0.10.20.30.40.5

0.60.70.80.91.0

Reflection Glossiness Chrome

105.0

0.6

0.7

0.8

0.9

1.0

Re

flectio

n G

lossin

ess

Fresnel IOR


Transparency percentage of material

2. If you don't see the transparency from the material preview window, that's because the Diffuse

layer transparency is set to black. Use this color to adjust the degree of Transparency. Click on the

color and change it to white, which will give you 100% of transparency to the material

Open file? ?We are going to introduce how to add and edit transparent

materials. Select the red cup from above. Under Properties>Material, select Edit to edit the cup's

material.

. Click on the “+” to the right of the Cup_Red, and then right click on Refraction Layers. Select Add

new layer. You will see a new layer (Refraction) added to the right of the window.

Cups - Refraction.3dm

Add transparent layer

1

Material: Refraction


Image on the left is what you will get. Do the same changes to the other two colors and you will get

an image similar to the one on the right.

3. Click on the Update Preview again and you will see the transparent but without its original red

color. When you set the transparency to 100% white, no matter what you have for diffuse color, it

will not show up. It will render like right hand side image below

The color of transparent materialWhen you want to apply color to the material without changing its transparency setting of 100% you

will have to do it with Fog Color, which is located to the lower right of the refraction dialog box

. Click on Fog Color and change it to the same color as the original Diffuse Color. Click the Update

Preview button and you will see the red color show up on the material this time

4

Fog Settings ExplainedThe appearence of Fog depends on three parameters; Fog Color, Fog Multiplier, and object

size. The Fog Color is a very important factor, and the wrong color can make it hard to

achieve your desired effect. It is best to set your color to a very light or desaturated version

of the desired effect. The Fog multiplier is completely based on the Fog color and object

size. The object’s size is important because Fog is created

by calculating how much light penetrates an object,

therefore a larger object will absorb more light than a

smaller object. This means that a single setting will not

necessarily create the same affect from object to object.

The image on the left is two spheres with the same material

applied to them, but the sphere on the left is 4 times larger.

The images below are tests of different multipliers with a

desaturated and saturated color.


2.01.00.90.80.70.6

0.50.40.30.20.10.0

Fog Multiplier

Fresnel IOR：1.55Refract IOR：1.55IOR：1.55Fog Color：R175, G250, B0

2.01.00.90.80.70.6

0.50.40.30.20.10.0

Fog Multiplier

Fresnel IOR：1.55Refract IOR：1.55IOR：1.55Fog Color：R244, G250, B230


2.452.402.352.302.252.20

2.152.102.052.001.951.90

1.851.801.751.701.651.60

1.551.501.451.401.351.30

1.251.201.151.101.051.00

Refraction IOR

1.52～1.8

1.472

1.309

1.77

1.77

1.33

玻璃

甘油

冰

紅寶石

藍寶石

水

Glass

Glycerin

Ice

Ruby

Sapphire

Water

IORMaterial

1.0

1.00029

1.329

2.0

2.417

1.57

真空

空氣

酒精

水晶

鑽石

綠寶石

Vacuum

Air

Alcohol

Crystal

Diamond

Emerald

IORMaterial

The Index of Refraction

IOR (Index of Refraction) is used to calculate the amount of light refracted from transparent

object. The default IOR value is set to 1.55. Please see the chart for usual objects' IOR value.

Refer to images below for examples of different IOR settings.

Please note that the changing the IOR in the refraction layer does not have an affect on the

reflections of the object. The reflections are controlled by the fresnel IOR which is mapped in the

Reflection layer. The values between the reflection layer and the refraction layer are not linked,

although it is recommended that the values be the same


0.050.100.150.200.25

0.300.350.400.450.50

0.550.600.650.700.75

0.800.850.900.951.00

Refraction Glossiness

Refraction Glossiness by default is set to 1.00, please refer to the images below for examples of

different refraction glossiness settings. Images below have the Refraction IOR set to 1.55. When the

setting for Refraction Glossiness remains the same, different Refraction IOR will change the

Glossiness of the object.

The Glossiness of transparent materials

Similar to reflective objects, transparent objects also have an setting for Glossiness. Refraction

Glossiness will allow you to control the sharpness of an objects refractions. The Glossiness of a

transparent object usually used to represent different type of glass, for example, frosted glass.

Take note that a low refraction glossiness will eventually blur the object to the point that you can

no longer see through the material. It also must be noted that render times will increase with lower

glossiness settings.


Images below show the difference with and without the Affect Shadows checked.

The shadow of transparent materialsThere is an Affect Shadow option to the right hand bottom

corner of the Refraction dialog box, by default is

unchecked. When checked, the color of the transparent

object will affect the color of its shadow.

We recommend you have this option checked because it will

allow for more realistic shadows.

Image below shows the influence of Refraction Glossiness material to objects behind it. Objects

Gradient Map

Refraction Glossiness 0.6Refraction Glossiness 0.6Refraction Glossiness 1.0

Similar to howthe intensity of the Fog Multiplier affects its transparency, the Refraction Glossiness

becomes more pronounced in thicker objects


Double-sided materialUnder Options of each material, you will find the Double-sided selection. The default setting is

checked. This option is particularly important for transparent material. When this option is

unchecked, light that enters the inside of solids will not be rendered and show up black. The

reason to have this option is that sometimes you may want to disable this option when render

object with translucent material (See next page) in order to get the right texture

Unless you want to create some special effects, please have this option checked for the most of the

time.。

Translucent materialWe've talked about changing the Diffuse color to get the degree of transparency we want to create

before. White means 100% transparent, black means 100% opaque. You can create translucent

materials with colors anywhere between white and black. But now we want to introduce a

different translucent material. It is related to special light absorption materials. Open file ?and render it, you will get image like below on the left. You will see

that colors where partitions meet the outside box and at the base of the box are darker. This is

because the thickness of the object changes and the light travel distance changes also. So the

degree of light absorption varies. To create this kind of material, you have to check the

Translucency option under the Refraction. Image on the right is the rendered result for Layer 02.

Translucency.3dm


Check the Translucent box under Translucency first. Thickness is for

control of light pass through the object, the unit for this is unclear.

Keep these three settings as default. Other items required to

change include

Many rendering engines use Sub-Surface Scattering (SSS) to create this kind of material. Although most of materials have

certain degree of translucency, but this doesn't mean that you have to apply this kind of material to all of them. That will

increase the rendering time dramatically. This material is good for creating things like: wax, skin, milk, cheese, plastic and

jade which all have a little translucency in it.

Translucency is created by absorbing light to the object's surface so the color of the object will show up a little darker than

its original color. If you still think that it's too dark even though the original color is set to the highest Val 255, the best way

to fix it is increasing the intensity of your light in the scene.

1.Double-Sided must be unchecked so the light can get through the

inside of the object. So it won't become too dark.

2. Set IOR to 1 is just fine

3.Give a smaller value to the Refraction Glossiness will help

increase the glossiness area.

4. Do not use white color for the Transparency because that will

turn the object to completely transparent and become dark

after rendered due to absorb too much light. Do not use black

color, either. That will not allow light get through the object at

all. Pick a color anywhere between Val 80~150 will give you the

best result.


Self-illuminated material can make the object become a lightsource itself. It is not limited to a

certain shape like a regular light type. Every part of the object can be illuminated and used as a

lightsource.

Self-illuminated material are perfect to create objects like: light ball, light tube, light shade,

stylish lighting, cold light and lit screen. In order for illuminated objects to emit light GI must be

enabled.

Open the Emissive menu. By default the color is set to white, intensity to 1 and Transparency color

to black. Click on Material Preview and you will see a completely white material ball. Render it and

you will get the image like the one on the right

Open File Cups - Emissive.3dm? and we are going to show you how to create a self-illuminated

material. Select the green cup on the right. Under Properties>Material, click Edit to open the

Material editor dialog box.

. Click on the + next to the Cup_Green to pull down the layers. Right click on Emissive Layers and

select Add new layer. You will see the new Emissive layer added to the right side.

Add Emissive Layer

1

Material: Emissive


105.03.02.01.0

0.90.80.70.60.5

0.40.30.20.10.0

Intensity

Diffuse Color：R155, G155, B155Diffuse Transparency：R0, G0, B0

Emissive Color：R200, G161, B82Emissive Transparency：R100, G100, B100

Adjust the colorClick on the color box to change to a different color. Notice that if the setting of the Intensity is too

high, the color of the object itself will become close to white. Only the light emitted from the self-

illuminated object will carry the correct color. It is not recommended to use self emitting materials

as a normal lightsource. Just make it as a decorative object in the scene.

Please refer to below image chart for results of various Emissive Intensities. By controlling the

degree of Transparency under the Emissive Color, you can still keep the diffuse color of the object.

For example, when the Intensity is higher than 2, the diffuse color is washed out and become white.

To avoid the self-illuminated object become white, please also refer to the Color Mapping on page

74.

Adjust the Intensity

By Default the Intensity is set to 1. Below images are rendered with Intensity of 3 (L) and 5 ®.


5. Click on Update Preview and you will see the Bitmap is now on the material ball. Render it and

you will get the result as the image on the right.

4. After the bitmap is selected, the “m” now

becomes “M”. Click the Update button to

preview the bitmap. Click Apply and you can

use this bitmap as the light source

3.Under Bitmap click on the “m” to the

right of the File and pick a bitmap to use as

the light source

Texture Editor Setting

Aside from using colors for self-illuminated materials, you can also use texture maps as light

source.

. Click on the “m” to the right of the Color under Emissive control panel

. The Texture Editor will then open up. Select Bitmap from Type's pull down menu and you will see

the control panel show up to the right.

1

2

Please note that if any type of map is being used in Texture Editor, the Color and Intensity under

Emissive will no longer function. You can't use these two options to control the brightness of the

material any more. You need to click on the “M” and go back to the Texture Editor and adjust the

multiplier there. All other control options in the Texture Editor work the same.

Click on the “M” and go back to the Texture Editor. Pay special attention to below options as these

options are often used for controlling the Bitmap texture map

Multiplier: Controls the intensity of the Bitmap.

Default set to 1. Increasing this number will intensify

the color tone, brightness and color contrast.

Blur under Bitmap: Controls the blurriness of the

Bitmap. By default this is set to 0.15. Setting this to 0

will not have any blur effect to the Bitmap.

Override: Use this parameter to set the gamma value.

Repeat: Used to control the U and V tiling of the

Bitmap. Increasing the number will cause the bitmap

to be repeated withing the mapping coordinates

Rotation: Adjust the degree of rotation of the Bitmap.


The intensity of self-illuminated materials (ipod image) is independent of the environment

settings. The bitmap will still render with its own intensity setting. Use the same way to create cold

light effect. Also showed below are two other examples.


02. Select Bitmap from Type's pull down

menu

0 1 . C l i c k o n t h e t e a p o t . U n d e r

Properties>Material, click on Edit to open the

Material Editor. Pull down the Diffuse menu from

the right and click on the “m” next to the Color to

open the Texture Editor

Open file Teapot Matte.3dm?Render the scene and you will an image similar to the one on the left

with a reflection material applied to it. The Image to the right is the result of applying brushed

metal texture map. You can see clear difference between these two images.

Texture MappingMost of the time we can't just use reflection and refraction to create a material for an object. For

example: stone, wood, paintings, packages, and textiles. We must use some texture maps to create

these materials. Below are some examples of using texture map for rendering.

Material: Texture Mapping


08. Click on Add to create a new mapping

channel07. Make sure Show advanced UI is checked

06.Use mapping channels to adjust texture

UVS. Select the teapot first, switch to

Mapping dialog under Properties

05. Render it. Since we didn't assign custom

UVs for the texture map, it will use the object's

surface UVs to render

04. Click Update to preview the texture map. 03. Click on the “m” to the right of File

under Bitmap to select a Bitmap file


Image on the left shows the mapping widget rotated 90 degree; on the right is the rendered result.

11. Under Rotation, make the x value -90, then

left click on empty place. This will rotate the

mapping widget 90 degree off the x direction

and projects the Bitmap from front to back

Render and you will get an image like the one

below. Since the Planar projection projects the

Bitmap from top down, the texture map is not

yet showing the correct direction. Rotate the

mapping widget to change the direction of

projection.

10. Click on Show Mapping to display mapping

widget in the window

09. Pull down the projection menu and

change it from surface to planar

Surface projection will not show a widget.

You could also modify

the mapping widget

with standard

commands in the

viewport


Click on F10 to show the control point

for the Mapping widget. Move those to

adjust the size of the widgetCylindrical

SphericalBox

Mapping types and adjustment

Rhino has several different types of UV projections: Surface, Planar, Box, Spherical, Cylindrical and

Capped cylindrical. Rhino sets the default to Surface if there is no other projection assigned to the

object and render the object according to its UV directions.

When changed to a different projection. the default size of mapping widget is set to the perimeter

of the object.

Show Mapping is used to display the mapping widget in the scene. Within the working window, the

mapping widget can be moved, rotated and scaled.

An object can be set up to have multiple mappings. This is done through using multiple mapping

channels. Click Add in the mapping properties box to create a new channel. Any maps that are

intended to correspond with certain mapping channels must be

specifed through the Texture Editor in the Material Editor.

Under UV make sure that mapping is changed to Explicit Map

Channel and then change the map channel underneath to

correspond with the desired channel.

Type ofmapping, size and position of Mapping Widget, and project direction will all affect the

projection on the object. Of course, those will also affect the final render result. Below are

examples using teapot to show different UV settings.


4. After importing the map, if the Bump map

is the same as the Diffuse map, make sure

the U, V Repeat under UVW Transform have

the same value. For example, if Bump map is

using U: 2 and V: 2, the Diffuse map should

be the same. Otherwise, these two maps

will not align correctly. Also, set the

Multiplier on the left side with smaller value

like 0.1. If set the Value too high will result

an unnatural look of material

3. Click on the ”m” to the right of Bitmap,

select the same brushed metal material as

used in Diffuse for the teapot

2. Select Bitmap under the Type pull down

menu

Only images can for bump mapping in V-Ray

for Rhino

1. Click on the teapot and open the Material

Editor to edit the Bump map of the teapot. In

the Maps section of the Material Editor,

check Bump and click on the “m” to open the

Texture Editor.

Bump mapAlthough we can use Bitmap for most materials there are some textures like wall surfaces, tile,

wood, oil painting, leather and water, which all have the uneven surfaces. We must use bump maps

in order to create them.

Material: Bump map


Bump maps are created using the grayscale of the Bitmap to set the high and low texture. The bright part of the

Bitmap is considered as high part and the dark is low. The Bump map is seen more clearly at the part where the

object reflects the most of the light. Using Bump map texture to create bumped texture is only a visual effect, not

the true surface of the object. Look at the edge of the object and you will still see the smooth surface.

Displacement is the way to actually change the geometry of an object with a bitmap, but currently V-Ray for

Rhino 1.0 is not supporting this function.

Below are some examples of textures created with Bump map.

Earlier we talked about using reflection glossiness to adjust reflecting material's glossiness and

create a frosted look. If we add a Bump map to it now will make the object look even better. The

image on the left is using only reflection glossiness. The image on the right has Bump map added.

Image on the left is the result of using only brushed metal Bitmap. The surface of the teapot looks

very smooth. Image on the right is rendered with Bump map added to the teapot and its handle. You

can see the Bump texture within the brushed metal and handle.


You will get the left image if you apply the texture map directly without transparency map. The

black background of the texture map is blocking part of the cup. The image on the right is rendered

with transparency map.

What's Transparency Mapping?

Transparency mapping is a method of adjusting the transparency of either maps or certain material

properties. This is used mostly for creating product logo, sticker, decals, and numbers. Depending

on your needs it may be beneficial to model the actual object in the scene (i.e. if a raised logo show

close up), but using transparency maps is a quick, easy, and simple way to acheive the desired

effect.

Open File ?and render it. You will get the image on the left. The one on the right is

the decal that we will use.

Cup - Decals.3dm

Material: Transparency


A rendering of the object should be

s i m i l a r t o t h e i m a g e b e l o w. T h e

Transparency map is covering the entire

cup. That's because there is no mapping

applied to this cup yet.

3. Use Diffuse1 color to edit the color for

this Transparency map. Click on the “m” at

the right of Color to add more texture to

this map if needed

2.Click on the “m” at the right of Transparency to enter the Texture Editor. Load the Bitmap for the

transparency texture map. Make sure you uncheck the Tile first to avoid repeating this Bitmap on

the object

Use Photoshop, PhotoImpact or a similar image

editing software to create a black and white image

and save as .bmp, .jpg or .png.

1. Open the Material Editor and select Cup_Red; right click on Diffuse Layers to add a new layer and

you will have the dialog window as image on the right. A Diffuse1 control panel is added under the

Diffuse


The logic of Transparency maps

The idea behind Transparency maps is using a grayscale image to determine which parts of an object will be

visable. Black areas will conceal and white areas will allow it to be visable. A tone of gray will change to some

degree of transparency.

The white area has the color assigned in Diffuse1 and end up showing on the surface of the object after

rendered.

For the cup example above, after assigning a mask to the Transparency, the red color of the cup is affected by

the white area of the mask and no longer showing red. The second layer’s color in the diagram below is used to

cover the white area of the first layer.

4. Under Properties>Mapping, add a new channel. Change the projection to Planar and adjust the

mapping widget's size and position as image showed below. If the Tile remains checked, it will

render as the image on the right


The third example is adding another Diffuse2 layer, and assigning a 0 and a 180 degree gradient

Bitmap to Diffuse and Diffuse1 in Transparency. Give the Diffuse2 a third color to create this three-

color gradient rendering effect for the cup.

The next example is using another grayscale Bitmap as the transparency mask. Although it is not a

gradient image it works exactly the same.

Other uses of transparency

There are many ways to use transparency. Its not just used as a mask for text. Here are some other

examples of different uses. First, we will use a gradient Bitmap as the Diffuse Transparency mask,

let the yellow color of Diffuse1 show through the white area at the cup and create two gradient

colors on the cup as image on the right. This is the better way then using a gradient Bitmap directly

as the Diffuse texture because of its flexibility of changing colors. If you use a bitmap you will have

to make another Bitmap for any changes

or modifications


The example above can not have the transparent quality at the top and bottom of the cup because

of the black color in the grayscale gradient Bitmap. The last example here is to use a pre-made

gradient Bitmap as the Refraction Transparency map. Set the Diffuse Transparency to white, and

then assign the Bitmap to the Refraction map

Another example is to use gradient color in a transparent material. As in our previous examples, use

a gradient grayscale Bitmap as the Diffuse Transparency mask. Add a Refraction layer to create the

half transparent and half opaque effect.

Our next example is similar to the Third one. The only difference is we are adding a Refraction

layer, and changing the Transparency color of Diffuse2 to white. This will make the white area at

the middle become transparent. Rendered image as on the right


The reason for doing this test is to let users understand the importance between lighting and

material. Should adjustments be made to the material first or the lighting first?

3. Do not change the GI value and change the

Brightness to Val127 under the Texture Editor.

Render it again and the result is very close to the

first image on the top

2. Increase the GI value to 2 without changing the

color, the result is shown on the right

1. So far the cup and ground are using the same

Val230 off white color. Render it with the GI

default setting to 1 and get the result as image

shown on the right

Lighting plays a key role in the rendering process. You simply can't get a good rendering result

without a good lighting environment.

Light sources are divided into direct and indirect lighting. Direct lighting is using the light

command to create Rectangular Light, Omni Light, Spot Light and Linear Light and use directly on

the object. Indirect lighting means object receives light from a broader source, like an

Environment Light and Radiant light.

there aren’t any

lights in the scene. The light source will be from

Environment light.

Let's do a test first

Open the file Cup Illumination.3dm

Illumination: Environmental Lighting


The next image down shows the same semi-open space but adds

two openings in the wall. The brightness increased due these

openings. The last image shows that different locations for

openings will also affect the brightness of the scene

Interior or Exterior?

When facing the task of illumination, separate it into interior

illumination and exterior illumination. For example, place an

object on the ground without any wall surrounds it to block the

light. This would be exterior illumination. Interior means that

the object is blocked or enclosed by space in a way that the

environment light does not have a direct effect on the object.

The image on the top shows open space illumination and image

below that shows the semi-open space illumination.

The answer is easy. Of course the lighting is more important!

Lighting must be adjusted first! From the second rendering you

can see that there is too much light in the image because of the

setting of intensity of GI changed to 2.

Here is one more example to understand this. If there is a white

ceramic sink or tub in the bathroom, it will look black without

any light source in the bathroom. You wouldn’t try to adjust the

brightness of the white ceramic under this condition. And also,

from the material setting point of view, how can you get even

brighter when the color is set to val255? It would be ridiculous

even trying to create an Emissive or self-illuminated material on

the object at this time.

The only way to improve the lighting for dark place is adjusting

the brightness! From intensify the Brightness of Environment

light and regular light, or even add more lights to the scene are

the right ways to improve the illumination. It's not appropriate to

adjust the Brightness of the material assigned to the object to

improve the illumination.

You will be in trouble if you try to improve an image by changing

the materials instead of creating proper illumination. In other

words, whenever the intensity of the illumination in a scene

changes, it will affect the appearance of the material's texture.

You would have to adjust the material again if you worked like

this. Take another look at the white cup in the previous example

\. If you want to change the cup's color to red, under the GI

setting of 2, you must pick a real dark red in order to render the

color correctly. What if the user wants a lighter red color? Or

what will happen if there are more lights added to the scene? Are

you going to use some extra walls to block the light? Many

questions remain…

It is very hard to predict the render result under incorrect

illumination. That's because the output does not accurately

reflect the inputted settings.


From the two images above we can see that the colors of the floor and cup are rendered very close to actual

colors, which means the Environment lighting is set to correct intensity and brightness for creating good

illumination. If the intensity was too strong, it would make the floor and cup appear far to bright and would

not mimic the actual material color.

You should not adjust the brightness or intensity of the environment light if no other lights will be added to the

scene. While adding lights you should preform this test again to maintain the appropriate illumination levels.

As long as the illumination is under control, you can safely pick the colors or textures for the object.

Default setting is 1 for Environment light. In reality you shouldn't increase this number despite its location of

interior or exterior. Please refer to page 56 for “Environment light for semi-open space”.

2. Re-assign the R255 G100 B100 red color to the cup

and render; you will get the result as below.

1. Assign the Val 230 color to floor, R191 G19 B19 red

color to cup first.

Techniques to adjust the Brightness

Before render the scene, try to finish all of the modeling that is needed. This will simplify adjusting the

illumination. The number of objects, object location, material type, color and even size will all affect the

illumination in some way, but if the environment light is correctly determined it will make the rest of the

process easier.

As with digital photography, in order to get the correct colors, you must to get the correct the white balance

first. V-Ray's Environment light and lighting brightness are not controlled by a specific lighting unit, so it is

impossible to find the regular brightness for white balance setting. You can only try to get the correct setting

by rendering the result to evaluate if the illumination is enough in the scene.

again. This is an easy open space example, there is no light added to the

scene and the Environment light is currently set to 1. Using the floor color to get the correct white balance

reading is better because it takes the most part of the render result.

Using the white floor color to evaluate the white balance is the first step. Make sure the color under Material

Editor is set between Val180~230, not Val255. If we set it to Val255, it will render extremely bright white

without any depth after adding lights to the scene. So it is always a good idea to set the floor color brightness a

little bit lower to save some room for more light sources later.

Open the file Cup - Illumination.3dm


4. If you want the objects to reflect the HDR

image Environment as well, you can assign the

s a m e H D R i m a g e t o t h e E n v i r o n m e n t

Background. Make sure the UVW is set to

Environment. After the Background HDR is

added, the result is the image on the right

3. Make sure you check the Environment radio button under UVW after the file is selected. Render it

and you will get the image on the right. You can see the difference between this image and the

image using only color for Environment light

source.

HDR courtesy of Wouter Wynen

http://www.aversis.be

2. Choose Bitmap from Type, click on “m”

beside File and import an .hdr file.

HDR Environments

Instead of using a color for an environment it is possible to use an image for your environment. VRay

supports HDR image based lighting. Open file

. Open V-Ray for Rhino's Render Options. Open

the Environment menu and click on the “m” at

the right of GI to enter the Texture Editor

Cups - GI HDR.3dm

1

http://www.aversis.be/index.htm


Understand that because most HDRs are prepared by a third party, it may take sometime to adjust the

intensity to fit your scene and lighting needs. Sometimes you may also need to adjust the HDR's Horizontal

angle to better cooperate your own lighting direction.

Although an HDR image has better control of its brightness than a normal 24 bit Bitmap, it still can not

recreate the light source and brightness in the nature. So normally it's used only for Environment light

source. Also, unless the light source is very bright in HDR image, the rendered shadow is lighter and not very

clear. You will need to add more light in the scene to get the better shadows in this case.

Below are three images rendered with different

HDR images as the Environment light sources. You

can see the dramatic differences between each

image.


Bitmap Environments

If you do not have an HDR image, a regular Bitmap can also be used as an Environment light source.

However, it is highly recommended that you use HDR images in stead of standard bitmaps. Standard

bitmaps will have less brightness control, a less obvious light source, and softer shadows. Standard

Images are easier to obtain, and with a bit of time and tweeking they can create a decent

environment.

The three images on the right are rendered with different Bitmaps. Compared to HDR

environments, it is not easy to find where the light comes from and the shadow is not very clear.


When we begin to set up the illumination for an interior space, first we need to check how many

openings allow light in (this also includes transparent object like a window or door). You must also

determine whether you want the lighting in the final result to be from the environment or from

direct lighting because this will determine how you set up the environment.

Increase the GI to 8 and render again. The

result is closer to reasonable illumination.

Increase the GI Intensity to 4 and render it

again. The result below is little bit brighter.

Environment for semi-open space

We used an open space Environment in our previous example. Now we will try a semi-open interior

space to see the differences between the two.

Open file In the scene we have an enclosed cube with an opening on the right

side. There are some objects placed on the wall next to the opening and there is no light in the box.

All objects used a gray color (RGB 190,190,190), the current GI Intensity is 2, and the GI color is

light blue. Render it and you will get the almost black image on the right. This result is due to a lack

of direct light in the scene and only a small opening allows the Environment light to come in.

GI Environment.3dm


Irradiant light

Please keep the scene that has the GI intensity of 8. It's easy to spot some blotches in those images

from previous page. This happens when indirect lighting affects the object. It is more obvious when

the indirect lighting gets stronger, and this only happens when Irradiance Map GI engine is used.

This is the result of a lack of hemispheric subdivs and samples during the process of transferring

lighting data to the image.

Open V-Ray for Rhino's Render Options and then pulls down the Irradiance Map menu. Change the

Subdivs value from default 50 to 100, and Sample from default 20 to 40.

Render again and you will find it takes longer to render but yeilds a better result such as the image

on the right.

In fact, for most cases, you don't have to increase

these values as this high to get a better result if

there is proper light and brightness in the scene.

Even if the Environment is set to the desired setting, you may still encounter problems later when

you adjust materials for objects in the scene. When adding additional lights to the scene and

adjusting the materials, its unlikely you will get you desired result on your first render. It is

important, especially for interior scenes, that you determine the views that are going to be

rendered. This is because a different view may require different lights or intensities to obtain the

desired result. This is illustrated in the two images below. The images are two renderings of the

same model and the same lighting set up. The one on the left is an exterior veiw and the one on the

right is an interior view.


V-Ray has the ability to use different methods for calculating the light within a scene. To do this V-

Ray breaks the calculation into two types of light. The first is the primary bounce, which is the first

light bounce coming directly from a light source. The second type is the secondary bounce, which is

all of the other light bounces in the scene. With V-Ray you can specify exactly which method of

calculation for each of these bounces.

Open the Indirect Illumination control panel under Options. There are Primary Engine and

Secondary Engine in the panel below.

There are four options for Primary Engine: Irradiance Map, Photon Map, Quasi Monte-Carlo and Light

Cache. Default is set to Irradiance Map。

There are three options for Secondary Engine: Photon Map, Quasi Monte-Carlo and Light Cache.

Default is set to Quasi Monte-Carlo or you can select None to not use this Engine.

When switching between the different engines, the settings available will also change according to

the assigned engine.

Primary Engine

Secondary Engine

GI Engines

Primary Engine: Irradiance Map

Open file ?and open the Irradiance Map's control panel under Options. There is a

very important setting option here related to image

quality: Min Rate and Max Rate.

Default for Min Rate and Max Rate are -3 and 0

respectively. They are currently -8 and -7 in the file.

Render it and you will get image to the right. Notice that

the calculation speed is very fast, but the quality of the

shadow and cups is poor.

Cups - Irrdiance Map.3dm

Min Rate: controls the minimum sampling for each pixel. 0 value means 1 pixel as 1 sample. Value of -1

means 2 pixels as 1 sample. Value of -2 means 4 pixels as 1 sample and so on. Smaller values means fewer

samples being taken from the object, so the render qualities of shadow, reflection and refraction are not

very good.

Max Rate: controls the maximum sampling for each pixel.

0= 1 pixel uses 1 sample. 1= 1 pixel uses 4 samples. 2= 1 pixel

uses 8 samples and so on. Smaller values means fewer total

samples used to calculate the light. A larger value will result

in better quality but longer render time.

Default settings of -3 and 0 represents four passes of render job. From -3, -2, -1

to 0. So you can see the Prepass 1 of 4 to Prepass 4 of 4 from the render progress

dialog box. According to definitions above, having the same number of prepasses

does not mean the same render quality.


If you render with Irradiance Map as Primary Engine, you can give a smaller set of numbers for Min and Max

Rate to produce faster previews of the lighting and material settings in a scene. For example: -6 and -5 or

-4 to -3. Although the quality may not be good enough for a final image, it is ok for a preview. After the

scene is finalized, then you can render with higher value to get the best final quality image.

The image on the left is showing Irradiance Map's fouth Prepass calculation of Min Rate: -3 and Max Rate:

0.The Image on the right is the final result.

The image on the left is showing the second Prepass of -4 and -3. Image on the right is the final

result.


The image on the left is showing -3 to 0. Image on the right is showing -3 to 1. Although the one on

the right has the better final result, the difference is very little.

The image on the left is showing the second Prepass of -3 and -2. Image on the right is the final

result.

If an image has a sufficient min/max rate (-3,0) yet still produces blochiness then the subdivisions

and the samples can be increased.


When Min Rate and Max Rate are too low, “leaking light” tends to happens even if the objects are

joined together. See image on the left for example. This is due to lack of Samples when calculating

the Prepass. Of course, this only happens when using Irradiance Map for the primary engine.

The image on the left is rendered with Min Rate and Max Rate of -4 and -3. You can see light comes

through the corner clearly. Increase the value to -3 and 0 and you will see an improvement as seen

in the image on the right.

Primary Engine: Quasi Monte-Carlo

When using QMC as the Primary Engine, the render result will not have any blotchiness or leaking

light as seen when using Irradiance Map. There is no need for a Prepass either. While the QMC

engine will also create image which is very realistic, it does take a long time to render.

The image on the left is rendered with Irradiance Mapping and the image on the right is rendered

with QMC. Although the one on the right looks dusty, but compare to the perfect pure color image on

the left, the QMC is more realistic.

Depending on your settings you may get very sandy looking image with QMC as Primary Engine. To

solve this problem, you can either increase the

Subdivisions from default 8 to a higher value under

QMC's control panel


Subdivions are the most important factor for Light Cache. Subdivisions are used to decide how many light

paths are traced from the camera to calculate the light distribution. The actual number of samples is the

square of the number of Subdivisions. With the default setting of 1000 for example, the actual number of

paths will be 1,000,000.

When the image resolution is higher, this number must set it higher as well. A lower number could result in

an incorrect solution for the image. The best way to determine what the idea amount of subdivions is, is

to set a higher number first and render. Look at the progress window and monitor the progress of

subdivisions and calculate the number according to the percentage. Say the subdivisions number is 1000

for example, when the subdivisions is half way through its calculation, the rendering window's black dots

are almost gone, that means you only need to set the number between 500~600 and you will get the

correct render result. If the process is done but you still have a lot of black dots in the window, that

means the number of

subdivisions is not enough

and result will be off. The

image below is showing Light

Cache calculation that still

has a lot of black dots in the

image.

Secondary Engine: Light Cache

Light Cache is used to calculate the light distribution in the scene. Its calculation method is very similar to

Photon Mapping, but the total opposite. Photon Map starts with a straight path from the light source and

collects light energy along way. Light Cache starts from the camera instead. Some good points about using

Light Cache include: it doesn't have many setting options to deal with, it renders quickly and calculates

light correctly. On the downside, the user has to decide the amount of subdivs. This value is related to the

resolution of the image.

The image on the left is rendered with combination of Irradiance Map and QMC. The image on the right is

rendered with combination of Irradiance Map and Light Cache.


Another setting you should pay attention to is the sample size. This is used to define the distance

between each path. Smaller numbers will give you more detail and a clearer image, but use more

memory to render. Larger number will give you smoother image, but could lose details.

Please view the images below from top to bottom. Both Primary and Secondary bounces are using

Light Cache. The images on the left are using 0.02 as the Sample Size. The images on the right are

using 0.03 as the Sample Size. The images below only show difference between Sample Sizes.


2. Use Polyline tool to draw a straight line, open snap point mode, left click on the camera point

and move the mouse over to Target point. Look at the distance window below and that's the number

to use for the Override Focal Dist. In this case, 62.3724 is the number to use. Render it and you will

get the rendering with Depth of Field effect. By default the focal distance is determined by the

camera, but if you want to change the focal distance without changing the camera the you can use

this function.

How to find out the current setting of focus distance of the camera?

1 Open file ?as menu on the right, in perspective

view, right click on Viewport Title and select Show Camera. See image below,

the narrow point in the scene is the lens of the camera, the point on the

opposite side is the Target.

Cups - Depth of Field.3dm

What is Depth of Field?

We must use photography to explain Depth of Field. When taking a photo with a camera, the two

most important things are focus and exposure. If it's not properly focused, the image will become

blurry. Incorrect exposure will also affect the result. Depth of Field is related to focus.

Open V-Ray for Rhino's Render Options. Pull down Camera control menu and you will see Depth of

Field below. By Default it is off, check it if you want to have the depth of Field in the final

rendering. The most important control item is

Override Focal Dist.

Adding Depth of Field to the image is to make it more

realistic.

Depth of Field


Change Focal Distance

Go back to Camera's control panel, set the Aperture to 1.0, then input 47 for the Override Focal

Dist. and make it closer to the red cup's opening edge. Render it and will get the image on the left,

Green and orange cup becomes blurry. The image on the right is rendered with Override Focal Dist,

changed to 72, approximately at the front edge of the orange cup. So now the yellow and green cups

become blurry.

Size of Aperture

V-Ray does not use f-stops to control the amount of light as normal cameras do. A smaller number

has less of an effect on Depth of Field. A larger number will make the object very blurry and takes

longer time to render, especially when calculating the edge of object for Depth of Field. So we

recommend you start with smaller number and move your way up if you need stronger effect.

The image on the left is rendered without Depth of Field and image on the right is rendered with it's

Aperture set to 1.0 The Depth of Field has already show up in the image and the focus point is at the

green cup.

Hit the Tab key when the cursor is locked to the Target point, and then move the mouse. You will

find the direction from camera to Target point is locked. Move the cursor and the number for the

distance will change accordingly. Move the cursor to desire focus location and memorize the

number below. Use this number for the Override Focal Dist. and it becomes the new focus distance.

Hit the Tap key again to unlock the direction


The glass cups are products of Nachtmann

from Germany。

Below are some images showing more example of Depth of Field.


Photons

The image on the left is rendered without caustics. The image on the right is rendered with caustics

enabled. All of the settings are using the default setting.

Due to the rebound of light, the cups look brighter at the right.

After you start rendering, the process window will show the lighting

information. As the caustic effect in the scene first. It won't take much

time to render if the Caustic Subdivs and light setting are using default

setting

Open file and open V-Ray for Rhino's Render Options. Pull down the Caustic

control panel at the bottom. Check the on button to enable Caustics.

Cups - Caustics.3dm

What are Caustics?

Caustics are a lighting phenomena created by some materials, for example, metal, jewelry, glass or

liquid which rebound light around the object. It is more obvious when the light is stronger

Caustics


If you want better control of the quality of the caustics, you can change the light settings. With the

light selected, go the light properties window and increase the caustic subdivions from 1000 to

2000. Be aware that this will increase the prepare time for render Caustic effect.

The image on the right is rendered with Caustic Subdivs set to 3000, you can see the better quality

of Caustic effect in this case.

Go to the Caustics control panel. Change the Max Photons setting from 50 to 300. Render and the

result should look like the image on the right. Compare this with the image on the last page you will

find the Caustic effect is greater this time and smoother

Usually it's easier to spot the Caustic effect in a

darker scene. If the scene is brighter, you can try

increase the Multiplier to offset the difference.


If you scaled the liquid down, which would be more physically correct, the image would not look

realistic.

Use Scale or Scale2D to increase the size of liquid and that will solve the problem

Strange image

This requires some skills, and mainly comes from a problem with the model. Open file The

liquid and the glass are coplanar, which causes a problem with reading the materials of the model. Render it

and you will get image as below

Cup - Liquid.3dm

Liquid inside a transparent glass


Adjusting the lens

Right click on the Perspective window title, select the Viewport Properties from below. See image

below, you can input desire lens length here. A smaller number for wide angle lens or a larger

number for telescope lens.

If you don't want to have any significant deformation of the objects, try to avoid using wide angle

lens. A normal product can get the best perspective by using Rhino's default 50mm lens. Use

22~35mm lens for an interior shot.

Rotate the camera

Hold both Alt and Shift, then right click the mouse to rotate the camera. This will make the image

more dynamic.。

Adjusting Camera


Radius for Shadow edge

When using Point light, Spotlight and Direction light for light source, the shadow edge will be very

sharp. To soften it, adjust the Radius in the Shadow dialog box. Using Directional Light here for

example, Image on the left is rendered with Radius set to 0. Image on the right is rendered with

Radius increased to 0.05

The quality of Shadow

Unless shadows are disabled in global settings, all objects will cast shadows.

The quality of shadow is controlled by subdivions under light properties dialog box. Select the

rectangular light and under Sampling>Subdivs change the default number of 8 to 32. The higher

number will cost more time to render, but will produce smooth shadows.

The image on the left is

rendered with Subdivs set to

8; the image on the right is set

to 32.

Light and Shadow


For interior, use Directional Light to create strong sunlight come in from outside.

SpotlightPoint LightDirectional LightRectangular Light

All of the light types' detailed here are supported by V-Ray. Each of the types has some unique parameters, but

there are a several parameters that are consistent between all of the light types.

Point Light and Spotlight require that the user set the Decay type: Linear, Inverse and Inverse Square. The last

two will decay dramatically, so when using Inverse or Inverse Square, you must increase the multiplier. That

means that point lights and spotlights are greatly affected by the distantance from the object, so it will require

more adjustments with these lights.

The Intensity of Directional Light will not Decay at all in any distance, it usually used outside to mimic the

sunlight.

Lighting Parameters

Note that under very strong light conditions, these three index color control will cause the scene to be

rendered darker. If under an average brightness scene, the render image will lose some depth due to the

colors evening out, especially in off white scene, you can get a totally different effect.


HSV Exponential and Exponential are very similar, but HVS will keep the tone and intensity of the

color, like the image on the bottom left.

Intensity Exponential can maintain the RGB ratio, and will only affect the color intensity, like the

image on the bottom right

Types of Color Mapping

Open the Color Mapping panel under Options, V-Ray

default is set to the Linear Multiply option. Linear

Multiply is using an object's brightness to create color.

So Brightness over Val255 will be discarded. Objects

under strong light usually get washed out to white color, like the image on the left. Exponential

uses color intensity to control brightness and prevents this wash out situation, but the objects'

color will become light, like image on the right.

The function of Color Mapping

Color Mapping is a function to replace color from the rendered image. Sometimes the screen can't

show extremely bright color correctly. Use Color Mapping to fix this problem when it happens.

Color Mapping


Fixed Rate Sampler

Adaptive QMC Sampler

This sampler uses a standard rate of subdivisions for computing antialiasing. This is generally will take

longer to compute because in areas that do not need a detailed sampling(i.e. a smooth, flat plane) will

get the same amount of sampling as a very detailed portion(i.e. a mesh screen). This sampler can

produce very predictable and consistent renders.

Adaptive QMC is a better sampler for detailed scenes with blurry effects. For example, scenes with tiny

seams, thin lines, reflection or refraction glossiness, Depth of field, and texture on material map. Using

Adaptive QMC for above situations can get a better quality image.

By default, min Subdivisions is set to 1. This is the minimum number of samples assign to each pixel. In

most cases, you don't have to increase its value. Max Subdivs is the maximum number of samples assign

to each pixel, and default it is set to 4. For better image quality you should increase this value. Of

course higher number will result in longer rendering time. Those who want to have high quality image

should switch to Adaptive QMC Sampler when calculating

images.

V-Ray’s default image sampler is Adaptive Subdivision. See image below on the left. These thin lines

were rendered with the default settings and had some broken lines in towards the back of the plane.

Open the image Sampler under Options, the V-Ray default is Adaptive Subdivisions with a min rate of

-1 and a max rate of 2. For this example, set the Min rate directly to 0 will fix those broken lines, as

image on the right.

Adaptive Subdivisions Sampler

Under most circumstances, use default Sampler for Adaptive Subdivision can get a pretty goof result

already.

Antialiasing


The Pixel Aspect option is used to control the aspect ratio of the pixel. Please see the two images

below

Image Resolution

Saving Output

V-Ray can override the sizes set up by Rhino. Open V-Ray for Rhino's Render Options. Open the

Output control menu and check the box to Override Rhino to have V-Ray define the image size.

There are several size presets in V-Ray to choose from. Users can also provide a custom the size.

The unit used is pixels. The Image Aspect below is the height-width ratio for current size. Click on

the “L” to lock in this ratio. When one of the height or width has changed, V-Ray will calculate the

other value automatically according to this ratio.

Check the Save File button under the Render

Output and then click on the “…” to set up the

file path, and type the file name. When V-Ray

finishes rendering, the file will be saved

accordingly. Please note that next rendering

will override the previous one with the exact

same path, type and name.

Output


Keyboard Operation

+ / -: Zoom in and out

* : go back to original size

Arrow keys: move zoomed in

image

Mouse operation

Ctrl+left key: Zoom in

Ctrl+right key: Zoom out

Double click on left key: back to

original size

Middle wheel: move zoomed in image

Right key: show pixel information

This icon opens the color

and b r i gh tnes s con t ro l

dialog box. Click on both X

and X to update the color

adjustment and brightness

Click on this icon and V-Ray will render where the

mouse is pointed to first during the last portion of the

rendering process. This is very helpful if you want to

see the final result of particular part of the image. If

the result is not what you want, hit ESC to end

rendering process right the way

Click on this icon to open the frame stamp bar. Click

on the far left icon to show the frame stamp at the

bottom of the rendering window. By default the

contains the V-Ray version and render time. This

information will be saved with the file.

click this icon to open the information dialog box.

Right click on the rendering window to display pixel

information. Right-clicking within the rendering

window can also open this dialog box; release the

mouse to close this box

Clear the image.

Save the image.

Switch back and forth between different color

channels to display the image, which is also

including Alpha Channel and grayscale to display

the image in black and white.

Tools

The V-Ray frame buffer has some useful tools. Please see discussions below for each tool

V-Ray frame buffer


02

03

04

05

06

07

08

09

10

. Use RenderWindow command to render a small

part of the entire image for testing render settings.

Make sure you don't click on something else with

mouse while rendering. It will terminate the process.

.Before you determine the best lighting for the scene, hide all objects except the floor and

render a big area of that floor. This will give you the brightness of the scene easier and faster.

. All Subdivs will affect the quality of the image. Try using smaller values before you render the

final image.

. Use the minimum amount of lights in the scene to save rendering time

. Raise those objects that sit on the floor a little bit to have better shadow quality and to avoid

overlapping geometry.

. Use Depth of Field to increase the realism of the image.

. Add more memory to your machine.

. Use image editing software to improve the final image

. Use your spare time to render

If you think V-Ray for Rhino is awesome, please recommend it to your friends. Finally, hope

everyone enjoys playing with it!

The last few tips

Here we offer some tips and experiments from other users and hope to save some time and increase

the image quality

Under Render Options>System, try to adjust the render division. In some cases a smaller value

will render faster, in others large values will. As you do some test renders change the value and see

if it renders faster or slower.

01

Final Thoughts

Notes

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