For first lets answer the question: What has the specular to do with glossy reflection?

All is the answer specularity is physically seen an unsharp or glossy reflection of an light source or any other light part in the environment of an object, therefore also in vray the specularity is bound to the glossy reflection, V-Ray however gives you the possibility to use both: traditional “cheated” specular effects and real physical correct glossy reflections.

The specular color gives the main color of the reflection. a car paint p.e. might be “Ferrari red”, maybe uses also a Fresnel falloff with slight color variation depending on viewangle.

The Specular Layer parameters let you set the glossiness of the specularity (classic fake specular) and the glassy reflection, this can be set via texture, you can set a multiplier for the texture, shader or slider, a value of white or 1 will give a sharp non glossy reflection. a value of 0.8 will give a 80% glossiness (equals 20% roughness), you can adjust both values independently. and also you can deactivate either or with the check boxes “trace reflections” or “trace specularity”.

The glossiness subdivision controls the exactness of the calculation, higher values produce a more exact solution but render longer. most time when using proper AA settings 8 might be enough. for high level surfaces you might want to set a higher value like 16 or 32 etc. last not least there are also Fresnel settings below:

You can turn Fresnel behavior on or off, when on the layer transparency get disabled, because this is now controlled by the Fresnel, the IOR gives again real world behavior. in reality almost all materials have a certain amount of glossy reflectivity and also a Fresnel behavior with a certain IOR. Glass has a IOR of 1.5- 1,75, ceramics, plastics, polished wood, etc. have an IOR of 3-6, metals have IOR starting with 10 going up to 200. You can also adjust the color of the Fresnel. it does not have to be black and white. often gray shades or even slight colors give good results, as glossy reflections are very important for all kind of high level materials we have implemented 5 specular layers to mix!

You can each setup individually and blend them together via the specular layer transparency or Fresnel behavior. each layer can have its on glossiness, own anisotropy, colors, filters…this is excellent for car paints, silk, plastics, multilayer materials like coated woods, brushed metal etc.

You can also use one layer for only specular effects and one only for glossy reflection to have different controls and colors for both. the variation is only limited by your imagination:-)

The specular layer in the V-Ray material gives a totally new way to build materials, as all real world materials have a specular/glossy reflection, so it is good that they render fast in vray, also in combination with GI and refraction….

Specular Type

Type – Determines the type of BRDF (the shape of the highlight).

  • Phong – Phong highlight/reflections
  • Blinn – Blinn highlight/reflections
  • Ward – Ward highlight/reflections
  • Microfacet GTR (GGX) – Generalized Trowbridge-Reitz (GTR) highlight/reflections

Specular Color

Color – this is the specular color of the material.

Brightness – use this setting to adjust the brightness of a channel`s color. The Brightness setting functions somewhat like a multiplier and can be set to greater than 100%.

Texture Map – here an image texture or shader can be defined.

Mix Mode – use these parameters to mix the color and texture panes using one of four modes. The default mode for all channels is Normal. If you load a texture or shader, it is placed on a layer above the color (i.e. the texture is placed on top of the color). Please consult the Cinema4d documentation about the different mix modes.

Mix Strength – defines the mixing proportion between the texture and color.

Specular Layer Transparency

Fresnel IOR – the IOR to use when calculating Fresnel specular.

Texture – the direction is based on the selected texture or shader.

Reflectance 90 Degreereflection color.

Texture – the direction is based on the selected texture or shader.

Invert – This option simply inverts the Texture Map.

Reflectance 0 Degreerefraction color. Note that the actual refraction color depends on the reflection color as well.

Texture Map – the direction is based on the selected texture or shader.

Invert – This option simply inverts the Texture Map.

Specular Layer Parameters

Use Fresnel – checking this option makes the specular strength dependent on the viewing angle of the surface. Note that the Fresnel effect depends on the index of refraction as well.

Fix Dark Edges – when enabled, dark edges that some times appear on objects with glossy materials will be fixed.

Link Highlight Glossiness – when disabled, allows different values for the Hilight glossiness and Reflection glossiness, but this will not produce physically correct 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.

Texture – here an image texture or shader can be defined.

Mix Strength – defines the mixing proportion between the texture and color.

Invert – This option simply inverts the Texture Map.

Glossiness 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.

GTR Tail Falloff – Controls the transition from highlighted areas to non-highlighted areas for the GTR BRDF type.

Specular Layer Expert Settings

Trace Reflections – if this is off, reflections will not traced.

Trace Specular – if this is off, specular will not traced.

Trace Depth – represents the maximum number of bounces that will be computed for reflections and specular.

Back side – if this is true, specular will be computed for back-facing surfaces too. Note that this affects total internal specular too (when specular are computed).

Soften Edges

Cutoff – this is a threshold below which specular will not be traced. VRAYforC4D tries to estimate the contribution of specular 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.

Refl Dim Distance – enables the Dim distance parameter which allows you to stop tracing reflection rays after a certain distance.

Dim Distance -pecifies a distance after which the reflection rays will not be traced.

Dim Falloff – a fall off radius for the dim distance.

Use Glossy as GI – 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).

Affect Channels – Specify which channels will be affected by the reflectivity of the material.

  • Color Only – The reflectivity of the material will affect 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 – The reflectivity of the material will affect all channels and render elements.

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

Use Interpolation – Check this option to turn caching on. V-Ray can use a caching scheme similar to the irradiance map to speed up rendering of blurry reflections. The options for the interpolation of blurry reflections are also 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.

Min rate – this value determines the resolution for the first interpolation pass. A value of 0 means the resolution will be the same as the resolution of the final rendered image, which will make the interpolation similar to the direct computation method. A value of -1 means the resolution will be half that of the final image and so on.

Max rate – this value determines the resolution of the last interpolation pass.

Color threshold  – this parameter controls how sensitive the interpolation algorithm is to changes in the color of reflections. Larger values mean less sensitivity and smaller values mean more sensitivity and better results.

Normal threshold  – this parameter controls how sensitive the algorithm is to changes in surface normals and small surface details. Larger values mean less sensitivity; smaller values mean more sensitivity to surface curvature and small details.

Samples – this is the number of samples that will be used to interpolate the blurry reflections at a given point. Larger values tend to blur the detail, although the result will be smoother. Smaller values produce results with more detail, but may produce blotchiness if the Subdivs parameter has been set too low.

Specular Layer Anisotropy

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

Texture Map – here an image texture or shader can be defined.

Invert – This option simply inverts the Texture Map.

Anisotropy Rotation – determines the orientation of the anisotropic effect in degrees (rotation in degrees). Different brushed surfaces can be simulated by using a texture map for the anisotropy rotation parameter.

Anisotropy axis – controls how the direction for the anisotropic effect is chosen.

Texture Map – the direction is based on the selected texture or shader.

Invert – This option simply inverts the Texture Map.

In ward note it is not possible to have no specularity, the result will be black, this lies in the nature of ward, when using ward don not deactivate trace specular or do not set the specular glossiness to 1 use 0.99 instead p.e.

Example: The BRDF type

This example demonstrates the differences between the BRDFs available in V-Ray. Note the different hilights produced by the different BRDFs.

BRDF type is Phong

BRDF type is Blinn

BRDF type is Blinn

BRDF type is Ward

BRDF type is Ward

Example: The Reflection color parameter

This example demonstrates how the Reflection color parameter controls the reflectivity of the material. Note that this color also acts as a filter for the diffuse color (e.g. stronger reflections dim the diffuse component).

Reflection color is black (0, 0, 0)

Reflection color is black (0, 0, 0)

Reflection color is medium grey (128, 128, 128)

Reflection color is medium grey (128, 128, 128)

Reflection color is white (255, 255, 255)

Reflection color is white (255, 255, 255)

Example: The Reflection glossiness parameter

This example demonstrates how the Reflection glossiness and Hilight glossiness parameters control the hilights and reflection blurriness of the material.

Reflection/Hilight Glossiness is 1.0 (perfect mirror reflections)

Reflection/Hilight Glossinessis 1.0

(perfect mirror reflections)

Reflection/Hilight glossiness is 0.8

Reflection/Hilight glossiness is 0.8

Reflection/Hilight glossiness is 0.6

Reflection/Hilight glossiness is 0.6

Example: The Fresnel option

This example demonstrates the effect of the Fresnel option. Note how the strength of the reflection varies with the IOR of the material. For this example, the Reflection color is pure white (255, 255, 255).

Fresnel is off

Fresnel is off

Fresnel is on, IOR is 1.3

Fresnel is on, IOR is 1.3

Fresnel is on, IOR is 2.0

Fresnel is on, IOR is 2.0

Fresnel is on, IOR is 10.0

Fresnel is on, IOR is 10.0

Example: The Anisotropy parameter

This example demonstrates the effect of the Anisotropy parameter. Note how the different values stretch the reflections horizontally or vertically.

Anisotropy is -0.9

Anisotropy is -0.9

Anisotropy is -0.45

Anisotropy is -0.45

Anisotropy is 0.0 (no anisotropy)

Anisotropy is 0.0 (no anisotropy)

Anisotropy is 0.45

Anisotropy is 0.45

Anisotropy is 0.9

Anisotropy is 0.9

Example: The Anisotropy rotation parameter

This example demonstrates the effect of the Anisotropy rotation parameter. For all the images in this example, the Anisotropy parameter itself is 0.8.

Anisotropy rotation is 0.0 degrees

Anisotropy rotation is 0.0 degrees

Anisotropy is -0.45

Anisotropy rotation is 45.0 degrees

Anisotropy rotation is 90.0 degrees

Anisotropy rotation is 90.0 degrees

Anisotropy is 0.45

Anisotropy rotation is 135.0degrees

Bitmapped Anisotropy rotation (map in the upper-right corner)

Bitmapped Anisotropy rotation(map in the upper-right corner)