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The VRayScannedMtl material allows the rendering of scanned BRDF material data stored in .vrscan files. These files are produced by Chaos Group's own internal material scanner and accompanying material creator software.

The scanned material renders the captured appearance of an actual physical material sample, that has been scanned with special scanner hardware. The material goes beyond single-point BRDF capture and can faithfully represent the textured appearance of a large number of real-world surfaces using bidirectional texture function (BTF) approximation.

Because the scanned material simply reproduces the way a physical material responds to light, is has no notion of "diffuse" or "reflection" components, "normal" or "bump" maps.

The .vrscan files tend to be quite large as they need to pack a lot of data (they need to describe the BRDF of the material over its entire surface).

For more details on VRscans, please see the VRscans Chaos Scans documentation space for information on downloadable sample scenes and Frequently Asked Questions or visit the VRscans.com website.

Trace Depth – Controls the number of reflection bounces. A value of -1 means that the reflection bounces are controlled by the global V-Ray trace depth in the Global switches rollout of the Renderer Settings.

Cutoff – A threshold used to speed up reflections. If the contribution of reflections falls below this threshold, the reflections are not traced. This is similar to the Cutoff threshold of the VRayMtl material.

Bump and Parallax Zone – Determines the point where additional bump and parallax no longer exist and only natural height effects remain. This option is especially useful in side views of the material, where it might appear flat or less detailed. A value of 0 adds no additional bump and parallax. Value of 1 adds additional bump and parallax equally regardless of the view angle. All scanned materials by default have the most suitable value loaded for this parameter to achieve the most realistic look. If you need full control over the bump and the parallax, set the value to 1 and work with the Parallax and Bump Multipliers. 

Parallax Multiplier  – Adjusts additional parallax and edge displacement strength. 

Bump Multiplier – Adjusts the additional bump. 

Sampling Type – Determines which samples are taken around pixels involved in "blurry" effects such as anti-aliasing, depth of field, indirect illumination, area lights, glossy reflections/refractions, translucency, motion blur, etc.

Importance sampling – Bases the number of samples allocated to a value on the importance when it comes to things like distance from the camera or if more samples are needed to render a realistic result.
Uniform sampling – The number of samples is the evenly taken over the entire image.

Plain Materials – A strategy used for material display. It controls the visibility of textures (if present). Possible values are:

None – The full material evaluation is always used. The object must have valid UV coordinates.
Average BRDF – Averages the BRDF and can be used to speed up the rendering for previews. Because texture details are removed, this also removes any tiling artifacts that might arise if the scanned sample does not tile very well. UV coordinates are still needed because most BRDFs are slightly anisotropic.
Average isotropic BRDF – Smooth representation of the material with no maps visible.

Edges Displacement – Uses a special technique that makes the edges of the geometry appear slightly jagged inwards. This option is useful when rendering close-ups of materials with bumps. It is faster than actual displacement and helps to achieve better realism.

No Cached Light – Allows you to disable the cached light for the material, ensuring physical accuracy without the need to switch off GI of the entire scene. Disabling this option results in faster, but less physically accurate render. 

Fast volumetric translucency – Relevant only to volumetric translucent V-Ray scanned materials. When this option is enabled, the calculation of the volumetric translucency is fast, but less accurate. 

Prevent color bleeding – Prevents the color bleeding.

 – When enabled, the indirect GI/glossy rays see the material as gray, thus preventing coloring of the near objects.