Here you can adjust color intensity, turn shadow on or off. You can also define if you want to use real world light decay or not.

Light type – specifies the light type:

  • Omni light – An Omni light source acts like a real life light bulb — casting rays in all directions, also used for IES light to be active.
  • Spot light – Spotlights cast their rays in just one direction, which is along the Z-axis by default.
  • Infinite light – light type is so called because it mimics light that is cast from an infinite distance, like Sun light.
  • Area light – The light rays from an Area light expand from all points on its surface outwards in all directions. A rectangular computer screen is a good example of such a light.
  • Parallel light – Parallel lights resemble a very distant light source. The Parallel light has an origin and simulates a large, single axis wall of light. These lights take the appearance of an infinitely large surface, radiating parallel light in a single direction.
  • Ambient light – specific light source that can be used to create light that doesn’t come from a specific direction. It can be used to simulate GI, ambient occlusion etc

Intensity Units – allows choosing the light units. Only in Area light type mode. Using correct units is essential when you work with the VRayPhysicalCamera. The light will automatically take the scene units scale into consideration to produce the correct result for the scale you are working with. The possible values are:

  • Default (image) – 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).
  • Luminous power (lm) – total emitted visible light power measured in lumen. When this setting is used, the intensity of the light will not depend on its size. A typical 100W electric bulb emits about 1500 lumen of light.
  • Luminance (lm/m/m/sr) – visible light surface power measured in lumen per square meter per steradian. When this setting is used, the intensity of the light depends on its size.
  • Radiant power (W) – total emitted visible light power measured in watts. When using 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.
  • Radiance (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.

Intensity – the light intensity in the units chosen by the Intensity Units parameter.

Texture – specifies the texture to use.

Cut-off threshold – this parameter 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 0.0, the light will be calculated for all surfaces.

Light color presets – some common Kelvin Light Source temperatures coupled with their RGB Equivalents. Note that this temperature has nothing to do with how “hot” a light source is – just with the color of its light. A light source with a low Kelvin temperature is very red. One with a high Kelvin temperature is very blue. More accurately, when we see two light sources side by side in a scene, the higher Kelvin light appears more blue, and the lower Kelvin light appears more red. Its all relative.

Light color – the color of the light. When using photometric units, this color is mixed with Filter color from IES Light tab.

Texture – specifies the texture to use.

Affect diffuse – this determines whether the light is affecting the diffuse properties of the materials.

Diffuse Contribution – this determines whether the light is affecting the diffuse properties of the materials.

Affect specular – this determines whether the light is affecting the specular of the materials.

Specular Contribution – this determines whether the light is affecting the specular properties of the materials.

Area speculars – when this option is Off the particular light will be rendered as a point light in the specular reflections.

Enable shadows – when on (the default), the light casts shadows. Turn this option off to disable shadow casting for the light.

Shadows color – the color of the shadow.

Texture – specifies the texture to use.

Shadow bias – bias moves the shadow toward or away from the shadow-casting object (or objects). If the Bias value is too low, shadows can “leak” through places they shouldn’t, produce moire patterns or making out-of-place dark areas on meshes. If Bias is too high, shadows can “detach” from an object. If the Bias value is too extreme in either direction, shadows might not be rendered at all.

Shadow radius – adjusts the softness of non area shadows.

Shadow subdivisions – this value controls the number of samples VRAYforC4D takes to compute shadow. Lower values mean more noisy results, but will render faster. Higher values produce smoother results but take more time. Note that the actual number of samples also depends on the DMC settings.

Photon subdivisions – this settings define the quality of light sampling for caustic calculation.

Caustic subdivisions – this option controls the amount of photons that VRAYforC4D will trace to estimate caustics. Large numbers slow down the calculation of the causticsphoton map and may take more memory.

Beam radius – adjusts the wideness (radius) of parallel light.

Decay – allows choosing the behave of light intensity with distance. normally the light intensity is inversely proportional to the square of the distance from the light (surfaces that are farther from the light are darker than surfaces which are closer to the light). The possible values are:

  • None- when this option is on the intensity will not decay with distance.
  • Inverse – light intensity inversely proportional to the distance from the light.
  • Inverse square – light intensity inversely proportional to the square of the distance from the light. It`s normal behavior of light.

VRAYforC4D uses real to physical light calculation, therefore there is no parameter to set the light falloff distance, as in real nature the light fall of is always inverse square and only influenced by the intensity of the light. In vray it is just the same, the stronger a light is the wider the falloff is. We strongly recommend using decay for all kind of lights, it will give you better results. In Vray there is no need for cheating with lights.