This page provides information on the V-Ray Dome Light.
Page Contents
Overview
A Dome light shines inward at the scene as if from a spherical or hemispherical light source outside the scene extents. This light is frequently used for Image-Based lighting (IBL) using panoramic HDR images used as environments. HDRs with a Dome light can create realistic lighting as well as environmental reflections.
A Dome light's illumination comes from a hemispherical dome above the y-axis of the light, or as a full sphere.
UI Path: ||obj Network|| > V-Ray > V-Ray Dome
Main
These parameters can be found in the V-Ray Light tab of the parameters editor.
Enabled – Turns the light on and off.
Dome Spherical – When this option is enabled, the dome light covers the entire sphere around the scene. When disabled, the light covers a hemisphere only.
Adaptive Dome – Speeds up the rendering by optimising the sampling algorithm for the dome light. No light portals are needed with this setup. Light Cache must be set as the GI engine for this feature.
Invisible – Controls whether the shape of the Dome Light source is visible in the resulting render. When disabled, the source light is rendered in the current light color, otherwise the light source itself is not visible in the scene.
Note: This parameter only affects the visibility of the light when seen directly by the camera or through refractions. The visibility of the light with respect to reflections is controlled by the Affect Specular and Affect Reflections options.
Use Intensity Texture – When enabled, replaces the Intensity parameter with a float texture slot that will override the Intensity.
Intensity – Multiplier for the light strength; this is also the light intensity in the units set by the Units parameter.
Use Dome Texture – When enabled, the Dome Light uses the specified texture.
Texture – A texture slot for the dome light.
Color Space – Selects the color space.
Linear
sRGB
Texture Mapping – 
Texture Resolution – Specifies the resolution at which the texture is resampled for importance sampling.
Texture Adaptivity – V-Ray adjusts the number of samples taken for different parts of the texture depending on their brightness. A value of 0.0 specifies no adaptivity; a value of 1.0 specifies full adaptivity.
Subdivs – Controls the number of samples V-Ray takes to compute lighting. Lower values mean more noisy results, but will render faster. Higher values produce smoother results but take more time.
Note: The actual number of samples also depends on the DMC Sampler settings. By default, this parameter is controlled by the Min Shading Rate in the Image Sampler. To specify a value, enable the Use Local Subdivs parameter under the DMC tab in the V-Ray Renderer parameters.
Object ID – Specifies an integer object ID to the Dome Light.
Units – Specifies the light units. Using correct units is essential when using the V-Ray Physical Camera. The light will automatically take the scene's unit scale into consideration to produce the correct result for the scale you are working with. The possible values are:
Default – The color and multiplier directly determine the visible color of the light without any conversion. The light surface will appear with the given color in the final image when seen directly by the camera (assuming there is no color mapping involved).
Lumens – Total emitted visible light power measured in lumens. When this setting is used, the intensity of the light will not depend on its size. A typical 100W electric bulb emits about 1500 lumens of light.
Lm/m/m/sr – Visible light surface power measured in lumens per square meter per steradian. With this setting is used, the intensity of the light depends on its size.
Watts – Total emitted visible light power measured in watts. With this setting, the intensity of the light does not depend on its size. Keep in mind that this is not the same as the electric power consumed by a light bulb for example. A typical 100W light bulb only emits between 2 and 3 watts as visible light.
W/m/m/sr – Visible light surface power measured in watts per square meter per steradian. When this setting is used, the intensity of the light depends on its size.
Use Global Light Level – When enabled, the light will use the global light level setting.
Shadows
Enabled – When enabled, the light casts shadows. Disable this option to turn off shadows for the light.
Use Shadow Color Texture – When enabled, allows the specification of a texture for the shadows for this light. If used, it will override the Color parameter of the Shadows rollout.
Color – Controls the color of shadows for this light. Note that anything different from black is not physically correct.
Bias – Moves the shadow toward or away from the shadow-casting object (or objects). Higher values move the shadow toward the object(s) while lower values move it away. If this value is too extreme, shadows can "leak" through places they shouldn't or "detach" from an object. Other effects from extreme values include moire patterns, out-of-place dark areas on surfaces, and shadows not appearing at all in the rendering.
Shadow Mask – Specifies a texture for the shadows for this light. If used, it will override the Color parameter of the Shadows rollout.
Advanced
Affect Alpha – Determines whether or not the Dome Light is visible in the Alpha channel of the render. When enabled, you will have a white alpha where the background is visible. When disabled you will have black alpha where the background is visible.
Affect Diffuse – Determines whether the light affects the diffuse properties of the materials.
Affect Specular – Determines whether the light affects the specular of the materials. This means glossy reflections.
Affect Reflections – Determines whether the light will appear in reflections of materials, for both perfect and glossy reflections.
Diffuse Contribution – A multiplier for the effect of the light on the diffuse component.
Specular Contribution – A multiplier for the effect of the light on the specular component.
MoBlur Nsamples –Specifies the number of samples used to sample the light for motion blur.
Dome Target Radius – Defines a sphere around the light icon where photons are being shot when photon-mapped caustics or the global photon map are used.
Dome Emit Radius – Defines a sphere around the light icon from which photons are being shot towards the target radius area.
Dome Ray Distance – Specifies the maximum distance to which shadow rays will be traced in scene units.
Dome Ray Distance Mode – Specifies the mode for the Dome Ray Distance parameter.
Cut-off Threshold – Specifies a threshold for the light intensity, below which the light will not be computed. This can be useful in scenes with many lights, where you want to limit the effect of the lights to some distance around them. Larger values cut away more of the light; lower values make the light range larger. When this value is 0.0, the light is calculated for all surfaces.
Bumped Normal Check – When enabled, the bumped normal is used to check if the light direction is below the surface.
Use Multiple Importance Sampling – Enables of disables Multiple Importance Sampling (MIS) for the light. When MIS is enabled (the default), the light's contribution is split between direct illumination on the one hand, and GI (for diffuse materials) or reflections (for glossy surfaces) on the other. This means that portions of the light's contribution will end up in the GI render elements (or the reflection render elements respectively). In certain specific situations this is undesirable and this option can be used to always calculate the light contribution through direct illumination.
GI
Store With Irradiance Map – When this option is enabled and GI calculation is set to Irradiance map, V-Ray calculates the effects of the V-Ray Dome Light and stores them in the irradiance map. The result is that the irradiance map is computed more slowly but the rendering takes less time. The irradiance map can also be saved for later use.
Diffuse Multiplier – A multiplier for the diffuse photons.
Caustics Multiplier – A multiplier for the generated caustics by the selected object. Note that this multiplier is cumulative - it does not override the multiplier in the Caustics tab of the V-Ray Render Settings.
Photon Subdivs – Only relevant when calculating the Global Photon Map. Lower values mean noisier results and faster rendering. Higher values produce smoother results but take more time to render.
Caustics Subdivs – Only used when calculating Caustics. Lower values mean more noisy results, but will render faster. Higher values produce smoother results but take more time.