General

Parameters

General tab

Diffuse

Opacity

Reflection

Refraction

Options

Options

BRDF

Reflect interpolation

Refract interpolation

Maps

 

 

General

A special material - the VRayMtl - is provided with the V-Ray renderer. This allows for better physically correct illumination (energy distribution) in the scene, faster rendering, more convenient reflection and refraction parameters. Within the VRayMtl you can apply different texture maps, control the reflections and refractions, add bump maps and choose the BRDF for the material.

Parameters

General tab

Diffuse

 

Basic ParametersDiffuse Color - this is the diffuse color of the material. Note: the actual diffuse color of the surface also depends on the reflection and refraction colors. You can either specify a simple color or use a texture.

 

 

Roughness - this parameter can be used to simulate rough surfaces or surfaces covered with dust (for example, skin, or the surface of the Moon).This parameter can also be textured

 

Opacity

 

OpacityOpacity color - here you can assign opacity to the material where white is completely opaque and black is completely transparent. You can also assign a map by clicking the texture button. This way you can create a material that has a non-uniform opacity.

 

 

Reflection

 

Reflection

Reflection Color - reflection color. Note that the reflection color dims the diffuse surface color. This parameter can also be textured.

 

Enable Fresnel reflections - checking this option makes the reflection strength dependent on the viewing angle of the surface. Some materials in nature (glass etc) reflect light in this manner. Note that the Fresnel effect depends on the index of refraction as well.

 

Lock Fresnel IOR - allows you to unlock the Fresnel IOR parameter for finer control over the reflections.

 

Fresnel IOR - the IOR to use when calculating Fresnel reflections. Normally this is locked to the Refraction IOR parameter, but you can unlock it for finer control. This parameter can be textured.

 

Lock hilight glossiness - when this option is off you can enter different values for the Hilight glossiness and Reflection glossiness. However this will not produce physically correct results.

 

Hilight glossiness - this determines the size of the highlight on the material. Normally this parameter is locked to the Reflection glossiness value in order to produce physically accurate results.

 

Reflection glossiness - controls the sharpness of reflections. A value of 1.0 means perfect mirror-like reflection; lower values produce blurry or glossy reflections. Use the Subdivs parameter below to control the quality of glossy reflections.

 

Use interpolation - V-Ray can use a caching scheme similar to the irradiance map to speed up rendering of glossy reflections. Check this option to turn caching on. See the Reflection interpolation section for more details.

 

Max depth - the number of times a ray can be reflected. Scenes with lots of reflective and refractive surfaces may require higher values to look correct.

 

Subdivs - controls the quality of glossy reflections. Lower values will render faster, but the result will be more noisy. Higher values take longer, but produce smoother results.

 

Enable dim distance - enables the Dim distance parameter which allows you to stop tracing reflection rays after a certain distance

 

Dim distance - specifies a distance after which the reflection rays will not be traced

 

Dim fall off - a fall off radius for the dim distance.

 

Reflection exit color - if a ray has reached its maximum reflection depth, this color will be returned without tracing the ray further.

 

 

Refraction

RefractionRefraction Color - refraction color. Note that the actual refraction color depends on the reflection color as well. This parameter can be textured.

 

Glossiness - controls the sharpness of refractions. A value of 1.0 means perfect glass-like refraction; lower values produce blurry or glossy refractions. Use the Subdivs parameter below to control the quality of glossy refractions. This parameter can be textured.

 

IOR - index of refraction for the material, which describes the way light bends when crossing the material surface. A value of 1.0 means the light will not change direction. This parameter can be textured.

 

Use interpolation - V-Ray can use a caching scheme similar to the irradiance map to speed up rendering of glossy refractions. Check this option to turn caching on. See the Refraction interpolation section for more details.

 

Affect shadows - this will cause the material to cast transparent shadows, depending on the refraction color and the fog color.

 

Affect channels - Allows you to specify which channels are going to be affected by the transparency of the material

 

Color Only - the transparency will affect only the RGB channel of the final render

 

Color+alpha - this will cause the material to transmit the alpha of the refracted objects, instead of displaying an opaque alpha. Note that currently this works only with clear (non-glossy) refractions.

 

All channels - all channels and render elements will be affected by the transparency of the material

 

Max depth - the number of times a ray can be refracted. Scenes with lots of refractive and reflective surfaces may require higher values to look correct.

 

Subdivs - controls the quality of glossy refractions. Lower values will render faster, but the result will be more noisy. Higher values take longer, but produce smoother results.

 

Refraction Exit color on- if this is on, and a ray has reached the maximum refraction depth, the ray will be terminated and the Refraction exit color returned. When this is off, the ray will not be refracted, but will be continued without changes.

 

Dispersion - this option enables the calculation of true light wavelength dispersion

 

Abbe - this option allows you to increase or decrease the dispersion effect. Lowering it widens the dispersion and vice versa.

Options

Options

 

Trace Reflections - check this option to enable reflections for the material.

 

Reflect on back side - when this option is not checked V-Ray will calculate reflections for the front side of objects only. Checking it will make V-Ray calculate the reflections for the back sides of objects too.

 

Trace Refractions - check this option to enable refractions for the current material.

Double-sided - if this is true, V-Ray will flip the normals for back-facing surfaces with this material assigned. Otherwise, the lighting on the "outer" side of the material will be computed always. You can use this to achieve a fake translucent effect for thin objects like paper.

 

Cutoff - this is a threshold below which reflections/refractions will not be traced. V-Ray tries to estimate the contribution of reflections/refractions to the image, and if it is below this threshold, these effects are not computed. Do not set this to 0.0 as it may cause excessively long render times in some cases.

 

Env. priority - this specifies how to determine the environment to use if a reflected or refracted ray goes through several materials each of which has an environment override.

 

Treat glossy rays as GI rays - this specifies on what occasions glossy rays will be treated as GI rays:

 

Never - glossy rays are never treated as GI rays.

 

Only for GI rays - glossy rays will be treated as GI rays only when GI is being evaluated. This can speed up rendering of scenes with glossy reflections and is the default.

 

Always - glossy rays are always treated as GI rays. A side effect is that the Secondary GI engine will be used for glossy rays. For example, if the primary engine is irradiance map, and the secondary is light cache, the glossy rays will use the light cache (which is a lot faster).

 

Energy preservation mode - determines how the diffuse, reflection and refraction color affect each other. V-Ray tries to keep the total amount of light reflected off a surface to be less that or equal to the light falling on the surface (as this happens in the real life). For this purpose, the following rule is applied: the reflection level dims the diffuse and refraction levels (a pure white reflection will remove any diffuse and refraction effects), and the refraction level dims the diffuse level (a pure white refraction color will remove any diffuse effects). This parameter determines whether the dimming happens separately for the RGB components, or is based on the intensity: Example

 

RGB - this mode causes dimming to be performed separately on the RGB components. For example, a pure white diffuse color and pure red reflection color will give a surface with cyan diffuse color (because the red component is already taken by the reflection).

 

Monochrome - this mode causes dimming to be performed based on the intensity of the diffuse/reflection/refraction levels.

 

 

BRDF

 

The BRDF parameter determines the type of the highlights and glossy reflections for the material. This parameter has an effect only if the reflection color is different from black and reflection glossiness is different from 1.0.

 

Type - this determines the type of BRDF (the shape of the highlight):

 

Phong - Phong highlight/reflections

Blinn - Blinn highlight/reflections

Ward - Ward highlight/reflections

 

Anisotropy - determines the shape of the highlight. A value of 0.0 means isotropic highlights. Negative and positive values simulate "brushed" surfaces.

 

Rotation - determines the orientation of the anisotropic effect in degrees (rotation in degrees).

 

Reflect Interpolation

 

Reflection InterpolationThese determine the options for the interpolation of glossy reflections. They are very similar to the options for the irradiance map. Note that it is not recommended to use interpolation for animations, since this may cause severe flickering.

 

 

 

 

 

Refract Interpolation

 

Refraction InterpolationThese determine the options for the interpolation of glossy reflections. They are very similar to the options for the irradiance map. Note that it is not recommended to use interpolation for animations, since this may cause severe flickering.

 

 

 

 

 

 

Material ID

 

The Material ID group is described here

 

Maps

In this section the user can see all the parameters of the materials that can be textured and assign appropriate maps to them. Additionally the settings for bump mapping can be found here.

 

Bump - this option allows you to select a texture for the bump or normal map.

 

Bump amount - this is a multiplier for the bump map effect.

 

Bump map type - this determines how the Bump parameter is interpreted.