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Clarisse 5.0 Reference Guide

In the following section we will go through the many different lights that are available to the built-in renderer of Clarisse as well as discussing about light linking.

Common Lights Attributes

Most lights share a set of predefined attributes to control the illumination color, exposure, sampling quality etc...

Enable

Set if the light is active or not. A disabled light is skipped from renderering.

Color

The Color attribute defines the color of the light which can also be textured. In that case, the light performs importance sample to greatly improve the quality the sampling. Please refer to Sampling Resolution for more information.

Sampling Resolution

Sampling Resolution sets the resolution used for texture importance sampling when analyzing the input texture in order to identify bright areas. The idea is to favor sampling of areas that have most important features to improve render quality and reduce noise during light sampling. Sampling Resolution should ideally match the resolution of the texture map so that it doesn't miss important features that should contribute to the lighting. Please note that under sampling a texture doesn't introduce noise but can change the lighting.

Note

Geometry Lights have specific attributes to control texture importance sampling. Please refer to Geometry Light section for more information.

 

Sampling Resolution set to low. Note how the illumination of the sun is missing.

Sampling Resolution set to low. Note how the illumination of the sun is missing.

Importance sampling on an environment light

Importance sampling on an environment light

 

Note

This attribute has no effect when no texture is connected to the color attribute of the light.

Exposure

Exposure allows you to control the exposure of the light following this simple formula:

 

final intensity = color * 2 exposure

 

Mode

When available, the Mode attribute defines how the the intensity of the light should be computed. When set to Physical the intensity of the light is computed using the total surface size of the light. When in Normalized mode the light intensity is not affected by the surface of the light. While not physical, Normalized mode can be more convenient for artists since the light intensity doesn't change when the size of the light is modified.

 

Original scale

Original scale

Light scaled in Normalize mode. Notice how the intensity of the light is globally unchanged

Light scaled in Normalize mode. Notice how the intensity of the light is globally unchanged

Light scaled in Physical mode. Notice how the intensity of the light has largely increased.

Light scaled in Physical mode. Notice how the intensity of the light has largely increased.

Light Contribution

Light Contribution attribute allows you to control the contribution of the light at the shaded point. Light Contribution value is multiplied to the illumination received by the shaded surface from the light. While non-physical, Light Contribution can be very useful when used when textured with scopes for example used to adjust the intensity and color of the light in world space. It can also be used to perform some kind of light linking in texture space.

 

Light Contribution to white

Light Contribution to white

Texturing Light Contribution with a scope and a default texture.

Texturing Light Contribution with a scope and a default texture.

Using a scope to exclude the key light contribution on half the scene

Using a scope to exclude the key light contribution on half the scene

 

Note

It is very important to underline that Light Contribution texture space is evaluated using the shaded surface texture space. The renderer completely ignores lights transformations. It is not meant to create gobos.

Unseen by Camera

The Unseen by Camera attribute controls whether the light geometry is visible from the camera (primary rays).

Sample Count

Sample Count allows to control the number of samples used for light sampling. The number of samples have a direct impact on rendering times and image quality. A high number of samples typcially reduces the noise in the image but increases rendering time. Please note that in most cases, increasing the number of samples by 4 reduce the noise level by 2.

 

Noisy image resulting from an under sampled area light (16 spp)

Noisy image resulting from an under sampled area light (16 spp)

The area light is now sampled with 256 spp which result in a better looking image.

The area light is now sampled with 256 spp which result in a better looking image.

Light Occlusion

It is possible to enable light occlusion so that they are considered as a physical geometry for all types of rays. To enable light occlusion simply toggle Enable Light Occlusion attribute.

 

Light Occlusion off (default)

Light Occlusion off (default)

Light Occlusion on (note the shadow under the sphere light)

Light Occlusion on (note the shadow under the sphere light)

Low Light Threshold

Low Light Threshold allows you to control the value below which the evaluation of a light is skipped (considered occluded). This attribute is very useful to optimize render times in scenes with many lights as you can discards lights that almost not contributing to the image. By default, Low Light Threshold is set to Use Renderer which uses the value set in the renderer. You can override this value for each light in your scenes.

 

Low Light Threshold set to 0.01 (rendered in 27s)

Low Light Threshold set to 0.01 (rendered in 27s)

Low Light Threshold set to 0.2 (rendered in 23s) Notice the suttle lack of illumination

Low Light Threshold set to 0.2 (rendered in 23s) Notice the suttle lack of illumination

 

Important

Be careful when setting a value for Low Light Threshold. If the input value is set to high, it will introduce illumination artifacts such as early light cutoffs.

AOV Exclusive

When enabling AOV Exclusive the light is excluded (not rendered) from the beauty. It is only evaluated on Light Path Expressions that use the token X instead of L. Please note this flag works conjointly with the light label defined by the Light Path Expression Label attribute. Please refer to Light Path Expressions for more information.

Shadow Color

Shadow Color allows you to control the tint of the shadow per light. While this is not physical at all, it proves to be useful on some cases.

 

Original environment light

Original environment light

Same environment light with Shadow Color set to 0.5, 0.5, 0.5

Same environment light with Shadow Color set to 0.5, 0.5, 0.5

Path Depth

Path Depth attribute group regroups all attributes that allow you to control the visibility of lights along certain types of paths. These attributes are very useful if you want to disable light from reflections/refractions or if you want to exclude lights for direct or indirect diffuse illumination. By default, all lights contribute to an infinite number of bounces.

Total Max Depth

Total Max Depth allows you to set the maximum depth after which the light is considered disabled for all paths. The attribute is very useful if you want to cut the light after a certain level of recursion. When this attribute is set to 0, it acts as if the light was disabled.

 

All lights with a Total Max Depth set to Inifinite.

All lights with a Total Max Depth set to Inifinite.

Top light with a Total Max Depth set to 0. Note the light is disabled.

Top light with a Total Max Depth set to 0. Note the light is disabled.

Diffuse Max Depth

Diffuse Max Depth allows you to set the maximum depth after which the light is considered disabled for diffuse illumination. When this attribute is set to 0, it acts as if the light isn't affecting diffuse.

 

All lights with a Diffuse Max Depth set to Inifinite.

All lights with a Diffuse Max Depth set to Inifinite.

Top light with a Diffuse Max Depth set to 1. The light only affects direct lighting

Top light with a Diffuse Max Depth set to 1. The light only affects direct lighting

Top light with a Diffuse Max Depth set to 0. Note the light is reflected but doesn't contribute to diffuse.

Top light with a Diffuse Max Depth set to 0. Note the light is reflected but doesn't contribute to diffuse.

Reflections/Transmissions Max Depth

Reflections Max Depth and Transmissions Max Depth allow you to set the maximum depth after which the light is considered disabled for reflections or transmissions. When these attributes are set to 0, it acts as if the light isn't affecting reflections or transmissions.

 

All lights with a Diffuse Max Depth set to Inifinite.

All lights with a Diffuse Max Depth set to Inifinite.

Top light with a Reflections Max Depth set to 0. The light is invisible from reflections.

Top light with a Reflections Max Depth set to 0. The light is invisible from reflections.

Top light with a Reflections Max Depth set to 1. The light is invisible starting from the second reflection bounce.

Top light with a Reflections Max Depth set to 1. The light is invisible starting from the second reflection bounce.

Shadows Max Depth

Shadows Max Depth allows you to set the maximum depth after which the light stops casting shadows. When these attributes is set to 0, the light doesn't cast shadows.

 

All lights with a Diffuse Max Depth set to Inifinite.

All lights with a Diffuse Max Depth set to Inifinite.

Top light with a Shadows Max Depth set to 0. The light isn't casting shadows.

Top light with a Shadows Max Depth set to 0. The light isn't casting shadows.

Top light with a Shadows Max Depth set to 1. The light isn't casting shadows from the 1 bounce.

Top light with a Shadows Max Depth set to 1. The light isn't casting shadows from the 1 bounce.

Path Weights

By default, lights are physically correct so that they all contribute the same way for each path type. However Clarisse allows extra artistic controls so that you can control the weights/intensity of lights along certain types of paths. This set of attributes is very useful if you want to reduce or boost light intensity from a specific type of paths such as diffuse, reflections, transmission etc... There are two distinct groups of attributes controlling the intensity of direct and indirect paths.

 

Example of paths in a path tracer

Example of paths in a path tracer

Direct Path Weights

Direct paths are paths going from the shading point of the scene that was immediately hit by the camera ray

Attribute

Description

Diffuse Weight

Set the intensity of the light in direct diffuse paths.

Reflection Weight

Set the intensity of the light in direct reflection paths.

Transmission Weight

Set the intensity of the light in direct transmission paths.

Subsurface Weight

Set the intensity of the light in direct subsurface paths.

Volume Weight

Set the intensity of the light in direct volume paths.

Indirect Path Weights

Indirect ones are the ones that are bouncing in the scene because of material sampling.

Attribute

Description

Indirect Diffuse Weight

Set the intensity of the light in indirect diffuse paths.

Indirect Reflection Weight

Set the intensity of the light in indirect reflection paths.

Indirect Transmission Weight

Set the intensity of the light in indirect transmission paths.

Indirect Subsurface Weight

Set the intensity of the light in indirect subsurface paths.

Indirect Volume Weight

Set the intensity of the light in indirect volume paths.

 

Original Render

Original Render

Specular Weight at 200% Note how the reflections are stronger

Specular Weight at 200% Note how the reflections are stronger

Reflection Weight at 200% and Indirect Diffuse Weight at 200% It looks like there's an additional bounce.

Reflection Weight at 200% and Indirect Diffuse Weight at 200% It looks like there's an additional bounce.

 

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