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Overview
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The Options tab globally control some geometry, lighting, material, and texture aspects of the rendering. For example, these options can be used to disable all shadows in your scene, or to use probabilistic light sampling to speed up test renders.
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UI Path: ||Parameters tab|| > Options tab (with the V-Ray Renderer node selected)
Geometry
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Displacement – Enables or disables V-Ray displacement mapping.
Lights
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Default Lights – Enables the usage of the default lights when there are no light objects in the scene or when you have disabled lighting globally with the Use Lights parameter.
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Full Lights Evaluation – V-Ray goes through each scene light and evaluates it at each shading point. In scenes with many lights and lots of GI bounces, this leads to a lot of shadow rays being traced and rendering can become extremely slow. When GPU rendering, this will introduce probabilistic light calculations but will not allow the Number of Lights parameter to be set. Older V-Ray scenes with the Probabilistic Lights parameter disabled, will default to using this option. For more information, see the Probabilistic Lights example below.
Uniform Probabilistic Lights – V-Ray randomly chooses the specified number of lights and evaluates only those. Lower values make the rendering faster, but potentially more noisy. Higher values cause more lights to be computed at each shading point, thus producing less noise, but increasing render times. This option makes it possible to render images that would otherwise take a very long time, at the expense of possibly introducing more noise into the rendering. When GPU rendering, this will introduce probabilistic light calculations. Previous V-Ray 3 scenes that had the Probabilistic Lights parameter enabled, will default to using this option. For more information, see the Probabilistic Lights example below.
Adaptive Lights – Uses information from the Light cache to determine which lights to sample. If a Light cache is not used, uniform sampling will be used. Depending on the scene, it can be faster than the Full Lights Evaluation and Uniform Probabilistic Lights mode.
Number of Lights – Number of lights from the scene that are evaluated by V-Ray when the Light evaluation parameter is to either Adaptive or Uniform Probabilistic. To achieve a positive effect from probabilistic light sampling, this value must be lower than the actual number of lights in the scene. Lower values make the rendering go faster, but the result is potentially more noisy. Higher values cause more lights to be computed at each hit point, thus producing less noise but increasing render times. For more information, see the Probabilistic Lights example below.
Materials
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Reflection / Refraction – Enables (default) or disables the calculation of reflections and refractions in V-Ray maps and materials.
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Transparency Cutoff – Determines when tracing of transparent objects will be stopped. If the accumulated transparency of a ray is below this threshold, no further tracing will be performed.
Textures
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Maps – E nables (default) or disables texture maps. This option is useful for troubleshooting renderings, for example for determining the extent to which texture maps are contributing to noise or other rendering artifacts.
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Uninverted Normal Bump – When enabled, the normal bump in tangent space will not be inverted on flipped UVs.
Volumetrics
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Probabilistic Volumetrics – If enabled, the volumetrics will select a few samples along each ray based on the smoke density, and evaluate the volume lighting at those points. If disabled, the volumetrics will evaluate the lighting at each step of the raymarching algorithm. The probabilistic mode is particularly useful when using the progressive sampler in V-Ray, as well as when using complex lighting on the volume. This mode only applies to the Volumetric Grid (VRayVolumeGrid) currently.
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Num. GI Samples – The number of probabilistic samples to use for GI rays. The number of samples depends on whether the volumetric has emissive component. Brighter emission requires more samples, while pure smoke can work with fewer.
Rendering
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Abort Rendering On Missing Asset – When enabled, the scene will not render if an asset fails to load.
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Secondary Ray Bias – A small positive offset that will be applied to all secondary rays; this can be used if you have overlapping faces in the scene to avoid the black splotches that may appear. For more information, see The Secondary Rays Bias example below.
Clamp Max Ray Intensity – Uses the Max ray intensity value to s uppress the contribution of very bright rays, which can typically cause excessive noise (fireflies) in the rendered image. The Max Ray Intensity value is applied to all secondary (GI/reflection/refraction) rays as opposed to the final image samples, allowing fireflies to be effectively suppressed without losing too much HDR information in the final image.
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GI Texture Filtering Multiplier – Controls the filtering of all the textures in the scene when Global Illumination is calculated. Greater values make textures blurrier while smaller values make them sharper.
Raycaster
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Use Embree – Enables the Intel® Embree raycaster. For more information, please see the Use Embree example below.
Use Embree for Motion Blur – Enables the usage of the Embree library for motion-blurred objects.
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Note that the Embree raycaster derives its speed partly from the usage of single-precision floating point numbers, whereas the standard V-Ray raycaster selectively uses double precision. This lower precision of Embree might sometimes result in artifacts in scenes with very large extents. |
Units
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Override Meters Scale – 
Override Photometric Scale –
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Example: Secondary Rays Bias
This example shows the effect of the Secondary rays bias parameter. The scene below has a box object with a height of 0.0, which the top and bottom of the box occupy exactly the same region in space. Due to this, V-Ray cannot resolve unambiguously intersections of rays with these surfaces.
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Example: Probabilistic Lights
Below is an example rendering of a scene with 1089 sphere lights with the Cutoff threshold set to 0.0. Both images were rendered with the Progressive image sampler and ran for the same amount of time. When probabilistic lights are enabled, the image is much cleaner as V-Ray manages to compute more GI rays (which are the main source of noise in this scene).
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Example: Use Embree
The Embree raycaster process dynamically builds algorithms that best match the instruction set of the CPU, thus speeding up the raycasting process overall. Currently in V-Ray, the Embree process accelerates only the calculation of rays for static geometry (as opposed to dynamic or render-time geometry).
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