VRay

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VRay Materials A brief overview of each material parameter. Also found here: http://docs.chaosgroup.com/display/VRAY2MAYA/VRayMtl

VRayMtl1 Cheat Sheet

Contents

Basic Parameters

Diffuse Color
Surface Color
Amount
Multiplier for "Diffuse Color"
Opacity Map
Transparency/Alpha - should not be used for glass. Should be used for objects like: leaves, grass.
Roughness Amount
As roughness increases the surface looks more "flat" and "dusty"
Self-Illumination
Ambient light or “incandescence”. Surface emits light i.e. a tv screen

Reflection

BRDF Type
BRDF “Bidirectional Reflectance Distribution Function”. This is the model that describes how surface reflections behave.
Reflection Color
Reflection Color affects the colour and brightness of the reflections.
Amount
Reflectivity Multiplier
Reflection Exit Color
If a ray has reached its maximum reflection depth, this color will be returned without tracing the ray further.
Lock Highlight and Reflection Glossiness
Usually kept ON
Reflection Glossiness
Glossiness of 1 = sharp reflection highlight.
Glossiness of 0 = broad soft reflection highlight. See Glossiness guide.
Reflection Subdivs
Controls the quality of glossy reflections. Lower values will render faster, but the result will be noisier.
Use Interpolation
Obsolete
Use Fresnel
Use Fresnel falloff for reflections. Surfaces are less reflective facing camera, and become more reflective as they face away.
Lock Fresnel IOR to Refraction IOR
Usually kept ON
Trace Reflections
Trace Reflections are essential for realistic rendering.
Max Depth
Distance reflection ray travels before stopping. Higher depth, longer render.
Reflect On Back Side
Toggle if back-facing sides render reflections. Important with glass objects.
Soften Edge
Soften the edge of the BRDF at light/shadow transitions
Fix Dark Edges
Enabling this option will fix dark edges that some times appear on objects with glossy materials
Dim Distance On
Set how far reflection rays go, can be used to avoid distant object reflections.

Anisotropy

Anisotropy
Used to create the "smeared" or "brushed" look of metals
Anisotropy UV coords
UV override for the Anisotropic effect. Useful if you have repeating UVs
Anisotropy Rotation
Rotation of the "brushed" anisotropic texture.

Refraction

Refraction Color
Color of light bouncing around inside object. Used for colored glass
Amount
Multiplier for refractive amount.
Refraction Exit Color On
Toggle color refraction "exit point". Used for debugging refraction trace depth.
Refraction Exit Color
Change refraction exit color to something bright and noticeable.
Refraction Glossiness
Lower glossiness makes refracted light "frosty"
Refraction subdivs
Controls the quality of the refraction. Lower renders faster, but more noisey.
Use Interpolation
Allows vRay to cache the refraction information for faster renders.
Refraction IOR
IOR describes the way light changes direction when passing through a surface. For the greatest realism, refer to an IOR char to find the IOR of the material you are trying to emulate.
Fog Color
Fog color and multiplier affect clarity of the refraction i.e. water vs beer.
Fog Bias
Adjust to alter distribution of fog, i.e. more fog in thin areas vs thick.
Trace refractions
Toggle if refraction are evaluated.
Max Depth
Number of times a ray can be refracted. Scenes with lots of refractive and reflective surfaces may require higher values to look right.
Affect Shadows
Affect Shadows causes transparent objects to cast transparent shadows. Only works with VRay lights.
Affect Channels
Allows you to specify which channels are going to be affected by the tranparency of the material.
Dispersion
Dispersion enables the calculation of true light wavelength dispersion. Gives refraction "color".

Bump and Normal Mapping

Map Type
Specify bump map type. The two most common are: Bump map - (black and white height map) or normal map in tangent space.
Map
Map input for bump or normal map
Bump Mult
Bump depth multiplier
Bump Shadows
Toggle if map affects the shadows cast by the object
Bump Depth Scale
Scale for sampling the bump map. The exact value is calculated automatically, but can be scaled here.

Subsurface Scattering

It is recommended that you leave this off, and use the "Fast SSS" instead.

Options

Cutoff Threshold
A cutoff override for limiting the distance at which lights affect a surface.