VRayLightDome

This page introduces the V-Ray Dome light, which is used for environment lighting as well as Image Based Lighting with HDRIs.

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 High Dynamic Range Images (HDRIs) used as environments. HDRIs 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: ||V-Ray Shelf|| > VRayLightDome button

||V-Ray Shelf|| > VRayLightDome button

||V-Ray Menu|| > Lights > V-Ray Dome Light

||Create menu|| > Lights > V-Ray Dome Light

Basic Parameters

Enabled – Turns the VRayLightDome on and off.

Color Mode – Selects the mode in which the color of the light will be specified, either Color or Temperature.

Light Color – When Color Mode is set to Color, this parameter controls the color of the light. When using photometric units, this color is normalized so that only the color hue is used, whereas the light's intensity is set by the Intensity multiplier.

Temperature – When Color Mode is set to Temperature, this parameter controls the color of the light in degrees Kelvin.

Intensity multiplier – Multiplier for the light color.

Dome Spherical – When enabled (the default), the dome light covers the entire sphere around the scene. When disabled, the light covers a hemisphere only.

Dome Adaptive – 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.

Texture

Use Dome Tex – When enabled, the light uses a texture for the VRayLightDome surface.

Multiply By The Light Color – Causes the colors in the texture to be multiplied by the light intensity.

Dome Tex – Specifies an environment texture for the VRayLightDome object. Note: If an RGBA texture file (a file that contains an alpha channel) is used, the file's alpha output must be connected to the Dome Tex A attribute to utilize the alpha channel on the light.

Dome Tex A – Specifies an alpha texture for the dome light. Note: The default value of 1 (fully opaque) remains unchanged whenever a file texture is connected to the Dome Tex attribute, even if that file contains an alpha channel. For a file's alpha channel to be utilized, it's alpha output needs to be connected to this attribute.

Finite Dome

When enabled, the Dome Light is calculated differently, so that it has a physical size in the scene. Especially useful when an HDRI is attached to the light, since this option adds depth to the background. The dome can serve both as a background and to project the light texture on the ground. The Finite dome consists of a ground plane, a hemispherical upper part and a transition area between the two. For more information, see the Finite Dome example.

Finite Radius – Determines the radius of the Finite Dome.

Projection Height – Offsets the height of the environment map projection.

Ground Blend – Controls the transition between the ground plane and the hemispherical upper part of the Finite dome. A value of 0.0 means a sharp transition, whereas a value of 1.0 means that the dome morphs into a sphere. Intermediate values blend between the two.

Example: Finite Dome

This example shows how enabling the Finite Dome option adds depth to a scene's background and augments the lighting. It also adds a ground plane. With the Finite Dome, the object looks as if it is actually placed in the background scene.

Infinite

Finite

Example: Setting the scale of a dome light

Options

Invisible – Controls whether the shape of the VRayLight 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.

The Invisible attribute 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.

Affect Diffuse – Determines whether the light is affecting the diffuse properties of the materials. With this option off, there will be no diffuse contribution from the light.

Affect Specular – Determines whether the light is affecting the specular of the materials (i.e. glossy reflections). With this option off, there will be no specular contribution from the light.

Affect Reflections – Determines whether the light will appear in reflections of materials, for both perfect and glossy reflections.

Affect Atmospherics – When enabled, the light influences the atmospheric effects in the scene.

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.

Diffuse contribution – A multiplier for the effect of the light's diffuse contribution on a surface.

Specular contribution – A multiplier for the effect of the light on the specular of the surface.

Atmospherics contribution – Determines the amount of influence the light has on the atmospheric effects such as VRayEnvironmentFog, VRayVolumeGrid or Phoenix effects.

Sampling

Light cutoff 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 from the light; lower values make the light range larger. If you specify a value of 0.0, the light will be calculated for all surfaces. This parameter is not available when the renderer is set to V-Ray GPU.

Texture resolution – Specifies the resolution at which the texture is resampled for importance sampling.

Shadows

Shadows – Enables or disables the tracing of shadows.

Shadow 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 color – A multiplier for the shadows color. This option is inactive when the renderer is set to V-Ray GPU.

Photon Emission

Target radius – Defines a sphere around the light icon where photons are being shot when caustics are used.

Emit distance– Defines a sphere around the light icon from which photons are being shot towards the target radius area.

See the Target radius and Emit distance example below for more information.

Caustics subdivs – Used by V-Ray when calculating Caustics. Lower values mean more noisy results, but faster render. Higher values produce smoother results but take more time to render. This option is inactive when the renderer is set to V-Ray GPU.

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 render rollout section. This option is inactive when the renderer is set to V-Ray GPU.

Example: Target radius and Emit distance

The example below shows how increasing the Emit distance and Target radius parameters affect the caustics effect. The Dome light gizmo shows the area where the caustics are generated. Higher Emit distance value makes the effect more spread out and blurry.

Target radius = 20, Emit distance = 25

Target radius = 15, Emit distance = 20

Target radius = 40, Emit distance = 45

UI

Locator Scale – Multiplies the size of the locator in the viewport. This does not affect the render.

Show in Viewport – Displays the texture loaded in the Dome Tex slot of the dome light as the environment in the viewport. You can disable the preview, preview only the texture, or preview the texture multiplied by the dome light's intensity.

Disabled – Disables Viewport Preview.
Texture Only – The specified texture will be previewed in the viewport.
Texture*Intensity – The specified texture multiplied by the light's intensity.

Advanced Options

Use Ray Distance – Enables the Ray Distance parameter.

Ray Distance – Determines the maximum distance to which shadow rays are traced. This option allows the use of the V-Ray Dome light inside a closed object.

Example: IBL (Image-Based Lighting)

The V-Ray dome light supports arbitrary texture maps that determine the amount of light coming from each direction on the virtual dome hemisphere. V-Ray then uses importance sampling to trace more rays in the directions where most of the light is coming from. This ensures speed and quality that were never before possible with pure gathering GI methods.

Easy setup for image-based lighting (IBL);
Importance sampling of the dome texture for fast and clean results;
Support for photon mapping for fast and accurate caustic effects.

In the following example, we will show how this works with an HDR image.

Initial position of the dome-light.
The Y axis is perpendicular to the ground plane.

Rendered image

Position 1
This time the dome is rotated along its Y axis to 90 degrees. Notice this has no effect, as the dome is using the same part of the HDRI.

Rendered image

Position 2
The dome is rotated along its X axis to 90 degrees. Now the dome uses another part of the HDRI.

Rendered image

Now we are going to show how rotating the HDRI can also affect the rendered image. We will rotate the HDRI from the Hypershade by selecting the VRayPlaceEnvTex node.