A luminescent object can be seen even when there are no lights in the scene. It is self-illuminated. So the luminance layer channel in VRAYforC4D gives real light to the scene when using GI. You can put in it any HDRI texture, any image or shader.
It also has a transparency or mask, when the transparency is set to 100% the parts that are not luminance are transparent and the layers below the luminance channel get visible, when the transparency is set to 0% the dark parts of the channel are just shown dark.
The luminance channel can be used to lighten a material, to make an object emit light, to make parts of an object emit light (like luminescent letters on a digital sign p.e.), and it can also be used to insert images (in the background p.e.) that should have a certain lightness, in the texture multiplier you can set values far over 1 to simulate real light or to give more power to textures. the result is a HDRI like effect. You can also use the filter shader p.e. to set the gamma of an image or to set the exposure of an HDRI image.
Color – this is the luminosity color of the material.
Amount – use this setting to adjust the brightness of a channel color. The Brightness setting functions somewhat like a multiplier and can be set to greater than 100%.
Texture – here an image texture or shader can be defined, also in luminosity layer you can put as texture map HDRI on a sphere or skydome to lighten your scene with HDRI or shaders.
Amount – this is the multiplier for the texture. Note that this does not affect the Color.
Radius – this parameters determines the amount of area (in scene units) where the VRayDirt effect is produced.
Texture – this texture map control the radius area. The texture intensity is multiplied by the radius to calculate the final radius at a given surface point. If the texture is white at a given surface point, the full radius value is used. If the texture is black, a radius of 0.0 is used.
Occluded color – this is the color that will be returned by the texture for occluded areas. You can use a texture map or Cinema4D shader for this parameter.
Unoccluded color – this is the color that will be returned by the texture for unoccluded areas. You can use a texture map or Cinema4D shader for this parameter.
Distribution – this parameter will force the rays to gather closer to the surface normal. The effect is that the dirt area is being narrowed closer to the contact edges. For ambient occlusion, set this parameter to 1.0 to get distribution similar to the ambient lighting on a diffuse surface.
Falloff – this parameter controls the speed of the transition between occluded and unoccluded areas.
Subdivision – controls the number of samples that takes to calculate the dirt effect. Lower values render faster but produce a more noisy result.
Bias (X,Y,Z) – these parameters will bias the normals to the X (Y,Z) axes, so that the dirt effect is forced to those directions. Consider that these parameter can also take negative values for inversing the direction of the effect.
Ignore for GI – this check-box determines whether the dirt effect will be taken into consideration for GI calculations or not.
Consider same object only – when on, the dirt will affect only the objects themselves, without including contact surfaces and edges. If off, the entire scene geometry is participating for the final result.
Invert normal – this option allows to revert the effect with respect to surface normals – e.g. instead of crevices, open corners will be shaded with the occluded color.
Work with transparency – when on, VRayDirt will take into account the opacity of the occluding objects. This can be used, for example, if you want to calculate ambient occlusion from opacity-mapped trees etc. When off (the default), occluding objects are always assumed to be opaque.
Ignore Self Occlusion – allow dirt to be self occluded.
Note that working with correct opacity is slower, since in that case VRayDirt must examine and evaluate the material on the occluding objects..
Color – this is the transparency color of the material.
Amount – use this setting to adjust the transparency of a channel. use this setting to adjust the transparency of a channel.
Texture Map – here an image texture or shader can be defined.
Invert – This option simply inverts the Texture Map, so transparent and solid areas are reversed. This works for both clipped images and images with built-in alpha channels.
Double Sided – checking this option makes the object emit light from its back side as well. If this is off, the material is rendered as black on the back sides.
Emit on Back Side – checking this option makes the object emit light from its back side as well. If this is off, the material is rendered as black on the back sides.
Compensate Exposure – this option is used when rendering with the Vray Physical Camera. When enabled the intensity of the material will be adjusted to compensate for the camera exposure.
Direct illumination – allow you to turn the objects with Luminosity Layer into actual direct mesh light sources.
Use VrayDirt – This option turn on VrayDirt.
V-Ray Dirt Mixing – use these parameters to mix V-Ray Dirt.
Direct Illumination Parameters
Intensity – the light intensity in the units chosen by the Intensity Units parameter.
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.
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.
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.
Affect reflections – this determines whether the light will appear in reflections of materials.
Invisible – this setting controls whether the shape of the source is visible in the render result. When this option is turned off the source is rendered in the current Light color. Otherwise it is not visible in the scene. Note that this option only affects the visibility of the light when seen directly by the camera or through refractions.
Subdivisions – this value controls the number of samples VRAYforC4D takes to compute lighting. 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 sampler settings.
No decay – 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). When this option is on the intensity will not decay with distance.
Store with Irradiance Map – when this option is on and GI calculation is set to Irradiance map VRAYforC4D will calculate the effects of the Light and store them in the irradiance map. The result is that the irradiance map is computed more slowly but the rendering takes less time. You can also save the irradiance map and reuse it later.
Light portal – light will be used like light portal.
- Normal light – when this option choosed, light used like normal light, not like light portal.
- Portal light – when this option is on, the Color and Multiplier parameters are ignored; instead the light will take its intensity from the environment behind it.
- Simple portal light – this option tells light that there is nothing of interest behind the light itself, and so the environment color can be used directly. Normally, the portal light takes its color from whatever objects are behind it. In order to do this, the light traces additional rays, which may slow down the rendering. Turning this option on makes the rendering of portal lights faster.
Ignore light normals – normally, the surface of the source emits light equally in all directions. When this option is off, more light is emitted in the direction of the source surface normal.