This page provides information on the V-Ray Directional Light, also known as a Direct Light.
Page Contents
Overview
The V-Ray Direct Light is a V-Ray specific light source that casts parallel light rays in a single direction.
UI Path: ||obj Network|| > V-Ray > V-Ray Direct
Main
These parameters can be found in the V-Ray Light tab of the parameters editor.
Enabled – Turns the light on and off.
Intensity – Multiplier for the light strength; this is also the light intensity in the units set by the Units parameter.
Use Color Texture – When enabled, replaces the Color parameter with a texture slot that will override the Color.
Color – Specifies the color of the Direct Light.
Decay – Controls the behavior of the light intensity in relation to the distance of the light source.
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, replaces the Color parameter with a texture slot that will override the Color.
Color – Controls the color of shadows for this light. Note that anything different from black is not physically correct.
Radius – Specifies the size of the light. A value of 0.0 makes the light a point light. Larger values will produce soft (area) shadows.
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.
Subdivs – Controls the number of samples for the area shadow of the Direct Light. Higher values produce area shadows with better quality but render slower. Note that this parameter is available for changing only when Use local subdivs is enabled in the DMC Sampler.
Shadow Mask – Specifies a texture for the shadows for this light. If used, it will override the Color parameter of the Shadows rollout.
Advanced
Area Speculars – When enabled, the highlights will match the shape of the light. When disabled, highlights will always be calculated as if affected by a point light.
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.
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.
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.
Beam Radius – Specifies the radius of the beam of light. When a value of 0.0 is used, the light will not have a beam radius.
Bumped Normal Check – When enabled, the bumped normal is used to check if the light direction is below the surface.
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 Direct 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.