Parameter | Description |
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traceLightPaths | This enables bidirectional path tracing modes. PxrUnified has 4 integration modes, based on how light paths are sampled. More options are available and some are invalid based on selections. Similar to PxrVCM selections as noted below. More details on settings to come as the integrator is finalized. - Off
- Unidirectional path tracing, like PxrPathTracer
- On
- Bidirectional path tracing, like PxrVCM with connect on and merge off. Indirect Guiding is disabled.
- Photons Only
- Progressive photon mapping, like PxrVCM with connect off and merge on. Indirect Guiding is disabled. Photo Controls are then exposed.
- UPS/VCM
- Bidirectional path tracing with progressive photon mapping, like PxrVCM with connect on and merge on.
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maxPathLength | Controls the absolute upper bound on the maximum ray depth. For example, a value of 0 for this parameter will allow direct illumination only, while a value of 4 will permit up to 3 bounces of global illumination. Default value is 8. Ray Depth per diffuse or specular interaction is ignored. Accordion Image Slider |
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maxNumber | 5 |
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sliderHeight | 256 |
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labelsFilter | mpl |
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autoplay | true |
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maxRayDistance | This controls the distance (in scene units) an indirect ray will travel before being terminated. If your scene scale is such that objects far from one another would not visually interact indirectly you can use this to optimize the scene. Note that rays traveling through windows and other objects are indirect rays and may be terminated too early and disappear from glass refraction. (Imagine a render where you view a mountain range through your living room window, be sure these rays reach far enough.) |
catchAllLights | On the last hit, evaluate the lights without shadowing, the default is off (0.0). If you find refraction goes dark, setting this slider to 1.0 adds the full contribution of the light samples. Turning this on may brighten your scene. |
emissionMultiplier | Multiplies all emissive and "glow" properties set on materials and lights. |
accumOpacity | Controls whether or not the path tracer will keep track of accumulated opacity along the path. The default is off. If you plan to render refractive objects and care about alpha values for compositing, you might want to turn this on, car windows for example. |
specularCurvatureFilter | Filter the roughness for specular interactions, setting it to 0.0 is no filtering or "ground truth". The default is designed to reduce noise. |
numLightSamples | Controls the number of light samples for direct illumination per camera hit point. The default is 1. Small numbers may improve performance of interactive and progressive updates. Larger numbers may appear to converge better while being slower to update. |
numBxdfSamples | Controls the number of Bxdf samples for direct illumination per camera hit point. The default is 1. Small numbers may improve performance of interactive and progressive updates. Larger numbers may appear to converge better while being slower to update. |
numIndirectSamples | Controls the number of Bxdf samples for indirect illumination per camera hit point. The default is 1. Small numbers may improve performance of interactive and progressive updates. Larger numbers may appear to converge better while being slower to update. |
sssOversampling | Controls the number of subsurface rays to spawn per camera hit point. The default is 8. |
allowMultilobeIndirect | Allows the re-use of samples during hair rendering to speed up convergence. This may alter the resulting LPEs. |
rouletteDepth | Controls the ray depth to begin performing Russian Roulette. Russian Roulette may terminate rays after this depth especially if they contribute little to the result. The default is 1. |
rouletteThreshold | Controls the path throughput threshold below which to perform Russian Roulette. This controls at which point the contribution of the ray is unimportant enough to terminate the ray. The default is 0.2. |
directClamp | Sets the amount where values will be clamped, for direct lighting the default is high to preserve the dynamic range of a scene's lighting. Lowering it will reduce noise like fireflies at the cost of dynamic range. The default is 1000000.0 |
indirectClamp | Sets the amount where values will be clamped, for indirect lighting the default is low, this avoids noise in secondary effects that have already absorbed some energy anyway. Lowering it will reduce noise but also darken indirect effects. The default is 8.0 |
causticClamp | Sets the amount where values will be clamped, for caustics the default is high to preserve the light patterns that result from light focusing off of or through objects. Lowering it will reduce noise like fireflies at the cost of dynamic range. The default is 1000000.0 |