This page provides information on the Global Options rollout of the V-Ray Main render settings.
The global switches allow you to control various aspects of the renderer universally over your scene.
UI Path: ||V-Ray Main render settings|| > Global Options rollout
Render Cache – When enabled, V-Ray will use the new Modo Render Cache API (available in Modo 901 or later) to export the following types of geometry: curves and triangles generated by Modo's Fur Material, unbaked MeshFusion objects, and deferred meshes (since Modo 901 SP2). The following modes are available:
Don't Use – The mentioned geometry types will not be rendered.
Static – The render cache data will be sampled only for the currently selected frame in the timeline.
Animated – The render cache data will be resampled for each frame when rendering an animation.
Animated with motion blur – The render cache data will be sampled twice for each rendered frame to determine the velocity of any movement. The resulting motion blur is currently supported by Standalone RT CPU and GPU, but it will not be visible when using the V-Ray Frame Buffer with RT CPU or GPU.
Enable displacement – Enables (default) or disables V-Ray's own displacement rendering.
Use lights – Enables or disables lights globally.
Use hidden lights – Enables or disables the usage of hidden lights. When this is checked, lights are rendered regardless of whether they are hidden or not. When this option is off, any lights that are hidden will not be included in the rendering.
Don't render final image – When enabled, V-Ray will only calculate the relevant global illumination maps (photon maps, light maps, irradiance maps). This is a useful option if you are calculating maps for a fly-through animation.
Use global max depth – When enabled, globally controls the maximum the reflection/refraction depth. When this is disabled, the depth is controlled locally by the materials/maps. When this option is checked, all materials and maps use the depth specified in the Global max depth parameter.
Max transparency levels – Controls to what depth transparent objects will be traced.
Light evaluation – Determines how lights are sampled in scenes with many lights.
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 evaluation and Uniform probabilistic lights mode.
Full 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 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 – V-Ray randomly chooses the specified number of lights and evaluates only those. Lower values make the rendering faster, but potentially noisier. 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.
Number of lights – Number of probabilistic lights from the scene that are evaluated by V-Ray. 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 noisier. Higher values cause more lights to be computed at each hit point, thus producing less noise but increasing render times. For more information, see Example: Probabilistic Lights.
Global options – advanced
Render hidden geometry – When enabled, hidden geometry in the scene will be visible in the final render.
Shadows – Enables or disables shadows globally.
Show GI only – When this option is enabled, direct lighting will not be included in the final rendering. Note that lights will still be considered for GI calculations, however, in the end only the indirect lighting will be shown.
Disable self-illumination – Affects the self-illumination component of the material - the object will be rendered with or without it according to this setting.
Reflection/refraction – Enables or disables the calculation of reflections and refractions in V-Ray maps and materials.
Glossy effects – When enabled, replaces all glossy reflections in the scene with non-glossy ones; useful for test renderings.
SSS enabled – Enables or disables the rendering of sub-surface scattering
Transparency cutoff – Controls 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.
Maps – Enables or disables texture maps.
Filter maps – Enables or disables texture map filtering. When enabled, the depth is controlled locally by the settings of the texture maps. When disabled, no filtering is performed.
Filter maps for glossy/GI rays – Enable or disable texture filtering during GI calculations and glossy reflections/refractions. When off, texture maps are not filtered for GI and glossy reflections/refractions in order to speed up the calculations. If this option is on (the default), textures will be filtered in these cases.
GI texture filtering multiplier – Multiplier for the texture filtering for GI or glossy rays
Uninverted normal bump – A global option to prevent inversion of normal bump in tangent space on flipped UVs
Force back face culling – Enables or disables (default) back face culling for camera and shadow rays. When this option is on, the surfaces of objects which are turned away from the camera (or the light source, when tracing shadows) will appear fully transparent. This allows you to look inside closed objects when the camera is outside.
Secondary rays 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 Example: Secondary Ray Bias.
Clamp max ray intensity – When enabled, suppresses the contribution of very bright rays, which may typically cause excessive noise (fireflies) in the rendered image. Its effect is similar to the Subpixel mapping + Clamp output options of the section, but the Max ray intensity is applied to all secondary (GI/reflection/refraction) rays, as opposed to the final image samples. This allows fireflies to be effectively suppressed but without losing too much HDR information in the final image. Similar to the Subpixel mapping option, the Max ray intensity introduces bias in the rendered image, as it may turn out to be darker than the actual correct result.
Max ray intensity – Specifies the level to which all secondary rays are clamped
Enable 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.
Num. prob. samples – The number of probabilistic samples to use when Probabilistic volumetrics is enabled.
Num. GI prob. samples – The number of probabilistic samples to use for GI rays. This should be kept as a relatively small number in order to speed up GI calculations.
Example: Secondary Ray Bias
The first image shows what happens when you try to render the scene with the default settings. You can see the splotches in the GI solution, caused by the fact that rays randomly intersect one or the other surface:
In the second image below, the Secondary rays bias is set to 0.001, which offsets the start of each ray a little bit along its direction. In effect, this makes V-Ray skip the problematic surface overlaps and render the scene correctly:
Note that the Secondary rays bias affects only things like GI, reflections, etc. In order to render the scene properly, the material assigned to the box has its 2-sided option checked. This is so that the object looks in the same way regardless of whether the camera rays hit the top or the bottom of the box. If the material did not have this option checked, it would appear "noisy" even though the Secondary rays bias is greater than 0.0:
This example shows the effect of the Secondary rays bias parameter. The scene above has a box object with a height of 0.0, which makes the two sides of the box to occupy exactly the same region in space. Due to this, V-Ray cannot resolve unambiguously intersections of rays with these surfaces.
Example: Probabilistic Lights
Below is an example rendering of a scene with 1089 sphere lights with Cutoff threshold in V-Ray Light Settings 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).
Full evaluation is used
Uniform Probabilistic is used (8 lights)