Octane Photon Tracing Kernel

Node Inputs

• Max Samples: Sets the maximum number of samples per pixel before the rendering process stops. Higher values result in cleaner renders.

• Diffuse Depth: The maximum number of times a ray can bounce off of a diffuse or very rough surface. Higher values mean higher render times, but more realistic results. For outdoor renders, a good setting is around 4. For lighting interiors with natural light from the sun and sky, you need settings of 8 or higher. In the real world, the maximum diffuse bounces would not exceed 16. It is possible to use a value higher than 16, but this is not necessary.

• Specular Depth: Controls the number of times a ray refracts before dying. Higher values lead to higher render times, but more color bleeding and more details in transparent materials. Low values introduce artifacts or turn some refractions into pure black.

• Scatter Depth: The maximum path depth that allows scattering.

• Maximal Overlapping Volume: Determines how much space to allocate for overlapping volumes. Ray marching is faster with lo values, but it can cause artifacts where many volumes intersect.

• Ray Epsilon: The distance between the geometry and the light ray when calculating ray intersections for lighting and shadowing. Larger values push rays away from the geometry surface. Smaller values are more accurate, but cause artifacts on large or distant objects. Ray Epsilon is similar to ray tracing bias in other rendering engines. Adjust Ray Epsilon to reduce artifacts in large-scale scenes.

• Filter Size: Sets the filter size in terms of pixels. This can improve aliasing artifacts in the render. However, if the filter is set too high, the image becomes blurry.

• Alpha Shadows: Allows any object with transparency (Specular materials, materials with Opacity settings and Alpha Channels) to cast a shadow instead of behaving as a solid object.

• Caustic Blur: Reduces noise in caustic light patterns. High values result in soft caustic patterns.

• GI Clamp: Clamps the contribution for each path to the specified value. By reducing the GI Clamp value, you can reduce the number of fireflies caused by sparse but very strong contributing paths. Reducing this value reduces noise by removing energy.

• Photon Gathering Radius: The maximum radius where photons can contribute.

• Photon Gather Samples: Determines the maximum amount of photon gather samples per pixel between photon tracing passes. This is similar to the Max. Tile Samples, but it also affects the quality of the caustics rendered. Higher values give more samples per second at the expense of caustic quality.

• Exploration Strength: The higher this value, the more the photon sampling is influenced by which photons are actually gathered.

• Keep Environment: Used in conjunction with the Alpha Channel setting. It makes the background visible in the rendered image while also keeping the Alpha Channel.

• Light IDs: Light linking provides a way to include and exclude illumination contributions of light sources on objects in a scene. The light IDs are set in Emitter nodes under the Emission rollout for the Diffuse Material, and this light ID corresponds to the Light IDs found here in the KernelSettings. Octane has eight Light IDs, and you can also choose whether to enable the sun and environment separately.

• Light ID Linking Invert: Inverts the light linking inputs from Light IDs.

• Path Term(ination) Power: Tweaks samples-per-second vs. convergence (how fast noise vanishes). Increasing this value causes the kernels to keep paths shorter and spend less time on dark areas, which means they stay noisy longer, but it also increases samples-per-second. Reducing this value causes kernels to trace longer paths on average and spend more time on dark areas. In short, high values increase the render speed, but they may lead to higher noise in dark areas.

• Coherent Ratio: Increasing this value increases the render speed, but it also introduces low-frequency noise or blotches. Eliminating the blotchy appearance requires a few hundred or a few thousand samples per pixel to go away, depending on the contents of the scene.

Node Outputs

• Octane Photon Tracing Kernel: The output of the node can be plugged into the Kernel input of the Octane Render target in the Render Target Node Editor.

Attributes

• Max Samples

• Diffuse Depth

• Specular Depth

• Scatter Depth

• Maximal Overlapping Volumes

• Ray Epsilon

• Filter Size

• Alpha Shadows

• Caustic Blur: Reduces noise in caustic light patterns. High values result is softness in the caustic patterns.

• GI Clamp: Clamps the contribution for each path to the specified value. By reducing the GI Clamp value, you reduce the amount of fireflies caused by sparse but very strong contributing paths. Reducing this value reduces noise by removing energy.

• Nested Dilectrics: If disabled, the surface IORs are not tracked and surface priorities are ignored.

• Irradiance Mode: This renders the first surface as a white Diffuse material. Irradiance Mode works similar to Clay Mode, but it applies to just the first bounce. It disables the Bump channel and makes samples that are blocked by backfaces transparent.

• Max Subdivision Level: The maximum subdivision level that should be applied on the geometry in the scene. Setting to 0 disables subdivision.