Global Switches Overview
The global switches allow you to control various aspects of the renderer globally.
Displacement - enables (default) or disables V-Ray's own displacement mapping. Note that we also support the Rhino's displacement feature.
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 to look inside closed objects when the camera is outside.
Lights - enables or disables lights globally. Note that if you uncheck this, V-Ray will only use GI to light the scene.
Default lights - allows you to control the default lights in the scene.
- Off - the default lights in the scene will be always switched off
- On - the default lights are always switched on when there are no lights in the scene or when you have disabled lighting globally (see Light parameter).
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 for any reason (either explicitly or by type) will not be included in the rendering.
Shadows - enables or disables shadows globally.
Show GI only - when this option is on, 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.
Reflection/refraction - enables or disables the calculation of reflections and refractions in V-Ray maps and materials.
Max depth - enables the user to limit globally the reflection/refraction depth. When this is unchecked, the depth is controlled locally by the materials/maps. When this option is checked, all materials and maps use the depth specified here.
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 GI - enable or disable texture filtering during GI calculations and glossy reflections/refractions. When off (the default), texture maps are not filtered for GI and glossy reflections/refractions in order to speed up the calculations. If this option is on, textures will be filtered in these cases.
Max. transperancy levels - this controls to what depth transparent objects will be traced.
Transperancy cutoff - this 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.
Override materials - this option allows the user to override the scene materials when rendering. All objects will be rendered with the chosen Override color.
Glossy effects - this option allows the user to replace all glossy reflections in the scene with non-glossy ones; useful for test renderings.
Don't render final image - when this option is on, 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.
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. See below for a demonstration of the effect of this parameter.
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 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.
The first image shows what happens when you try to render the scene with 0 on the Secondary ray bias 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, 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:
Low thread priority - turning this on will cause V-Ray to use threads of lower priority when rendering.
Batch Render - when this enabled it allows users to render a sequence of images one after another. This is useful when rendering animations or using third party batch rendering plugins for Rhino.
Progress Window - when this is turned on, V-Ray will show the messages window at the start of every render.