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The Diffuse/Specular Ramps

 controls the diffuse/specular color based on the amount of light received. Position 0.0 maps to light intensity 0.0, position 1.0 maps to light intensity 1.0 and above.

BRDF– Determines the type of BRDF (the shape of the highlight and glossy reflections). This parameter has an effect only if

the Reflection Color

 is different from black

and Reflection Glossiness

 is different from 1.0.

Phong

 – Phong highlight/reflections
Blinn

 – Blinn highlight/reflections
Ward

 – Ward highlight/reflections
GGX

 – GGX Microfacet highlight/reflections

GGX Tail Falloff – Controls the transition from highlighted areas to non-highlighted areas when

the BRDF

Type is set

to GGX.

Color – The reflection color dims the diffuse surface color.

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

Lock Highlight Glossiness – When disabled, the user can enter different values for

the Hilight Glossiness and Reflection Glossiness. However this does not produce physically correct results.

Highlight Glossiness – Determines the shape of the highlight on the material. Normally this parameter is locked to the Reflection Glossiness value in order to produce physically accurate results.

Use Fresnel

 – When enabled, 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 (IOR) as well.

Glossy Fresnel – When enabled, uses glossy fresnel to interpolate glossy reflections and refractions. It takes the Fresnel equation into account for each "microfacet" of the glossy reflections, rather than just the angle between the viewing ray and the surface normal. The most apparent effect is less brightening of the grazing edges as the glossiness is decreased. With the regular Fresnel, objects with low glossiness may appear to be unnaturally bright and "glowing" at the edges. The Glossy Fresnel calculations make this effect more natural.

Lock Fresnel IOR to Refraction IOR

 – Allows the user to unlock the Fresnel IOR parameter for finer control over the reflections. When this is enabled, the Fresnel IOR is locked to

the Refraction IOR.

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. .

Subdivs – Controls the quality of glossy reflections. Lower values render faster, but the result is more noisy. Higher values take longer, but produce smoother results. Note that this parameter is available for changing only when Use Local Subdivs is enabled in the DMC Sampler.

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 a float value between 0 and 1 (where 0 is 0 degrees and 1 is 360 degrees). 

Uv Vectors Derivation

 – Specifies the method for deriving anisotropy axes:

Local Axis

 – Uses a local axis for the anisotropy effect.
UVW Generator – Allows the user to assign a UVW Generator for the anisotropy effect.

Axis

 – Specifies a local object axis for the anisotropy effect

when Uv Vectors Derivation

 is set

to Local Axis.

Trace Reflections – Enables reflections for the material.

Exit Color – If a ray has reached its maximum reflection depth, this color is returned without tracing the ray further.

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.

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 are not traced.

Dim Fall-off – A fall off radius for the dim distance.

Soften

 – Softens the edge of the BRDF at light/shadow transitions

Affect Channels

 – Allows the user to specify which channels are going to be affected by the reflectivity of the material.

Color Only

 – The reflectivity affects only the RGB channel of the final render.
Color+alpha

 – Causes the material to transmit the alpha of the reflected objects, instead of displaying an opaque alpha.
All channels

 – All channels and render elements are affected by the reflectivity of the material.

Translucency Type

 – Selects the algorithm for calculating translucency (also called sub-surface scattering). Note that refraction must be enabled for this effect to be visible. Currently only single-bounce scattering is supported.

None

 – No translucency is calculated for the material.
Hard (wax) model

 – This model is specifically suited for hard materials like marble.
Soft (water) model

 – This model is mostly for compatibility with older V-Ray versions (1.09.x).
Hybrid model

 – This is the most realistic SSS model and is suitable for simulating skin, milk, fruit juice and other translucent materials.

Color – Normally the color of the sub-surface scattering effect depends on the Fog color; this parameter allows you to additionally tint the SSS effect.

Fwd / Back

coeff – Controls the direction of scattering for a ray. A value of 1.0 means a ray can only go forward (away from the surface, inside the object);

 0.

5 means that a ray has an equal chance of going forward or backward; 0.0 means a ray is scattered backward (towards the surface, to the outside of the object).

Light Multiplier – Specifies a multiplier that controls the strength of the translucent effect.

Scatter Coeff

 – The amount of scattering inside the object. A value of 1.

0 means rays are scattered in all directions; 0.

0 means a ray cannot change its direction inside the sub-surface volume.

Maximum Thickness – Limits the rays that are traced below the surface. This is useful if you do not want or don't need to trace the whole sub

-surface volume.

– A threshold below which reflections/refractions are not 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.

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

Reflect On Back Side

 – When disabled, V-Ray calculates reflections for the front side of objects only. Checking it makes V-Ray calculate the reflections for the back sides of objects too.

Use Irradiance map – When enabled, the irradiance map is used to approximate diffuse indirect illumination for the material. If disabled, Brute Force GI is used in which case the quality of the Brute force GI is determined by

the Subdivs

 parameter of

the Irradiance Map. This can be used for objects in the scene which have small details that are not approximated very well by the irradiance map.

Fix Dark Edges

 – When enabled, fixes the dark edges that sometimes appear on objects with glossy materials.

Energy Preservation

 – 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 less than or equal to the light falling on the surface (as 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 remove any diffuse and refraction effects), and the refraction level dims the diffuse level (a pure white refraction color remove any diffuse effects). This parameter determines whether the dimming happens separately for the RGB components or is based on the intensity:

Monochrome – Causes dimming to be performed based on the intensity of the diffuse/reflection/refraction levels. 
Color

 – Causes dimming to be performed separately on the RGB components. For example, a pure white diffuse color and pure red reflection color yield a surface with a cyan diffuse color (because the red component is already taken by the reflection).

Glossy Rays as GI

 – Specifies on what occasions glossy rays are treated as GI rays:

Never

 – Glossy rays are never treated as GI rays.
GI Rays

 – (Default) Glossy rays are treated as GI rays only when GI is being evaluated. This can speed up rendering of scenes with glossy reflections.
Always

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

Refl. Gloss. Interpretation –These

options control how

Reflection Glossiness

 is interpreted.

When Use Glossiness

 is selected,

the Glossiness

 value is used as is, and a

high Glossiness

 value (such as 1.0) will result in sharp reflection highlights.

When Use Roughness

  is selected, the

Reflection Glossiness

  inverse value is used. For example, if

Reflection Glossiness

  is set to 1.0

and Use Roughness

  is selected, this will result in diffuse shading. Conversely,

if Glossiness

 is set to 0.0

and Use Roughness

 is selected, this will result in sharp reflection highlights. Note that

the Roughness

 parameter itself has no bearing on the results of this option. 

Use Environment Override

 – Enables the use of

the Environment

Override color.

Environment Override

 – A color or texture that is used as an environment for the material.

Environment Priority

 – Specifies the environment override priority when several materials override it along a ray path.