The Direct Light Kernel is generally used for faster preview rendering. Direct Lighting is not unbiased and will not yield photo-realistic results. However, because of its speed, it can be the ideal choice for rendering animations or stills depending on the demands of the project. Figure 1 shows the Direct Lighting settings in the OctaneRender settings tab.
Figure 1: The Direct Lighting settings in the OctaneRender tab.
Direct Lighting Kernel Parameters
Sets the maximum number of samples per pixel before the rendering process stops. The higher the number of samples per pixel, the cleaner the render. There is no rule as to how many samples per pixel are required for a good render. It is subjective and may vary depending on the content and complexity of the scene being rendered.
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 can become blurry.
Is 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. Lower values are more accurate, but can cause artifacts on large or distant objects. Ray Epsilon is similar to raytracing bias in other rendering engines. Adjust Ray Epsilon to reduce artifacts in large scale scenes.
This option removes background images or colors created by the SunSky environment node from the rendered image while not affecting any lighting cast by the environment. This can be useful if the user wants to composite the render over another image and does not want the background to be present. Note that objects appearing in the RGB channels will have a bleeding edge which may appear as noise artifacts however these edges are not included in the alpha channel itself.
Allows any object with transparency (specular materials, materials with opacity settings and alpha channels) to cast a shadow accordingly instead of behaving as a solid object.
Controls the number of time a ray can be refracted before dying. Higher numbers mean higher render times but more color bleeding and more details in transparent materials. Low numbers can introduce artifacts or turn some refractions into pure black.
Controls the number of times a ray can be reflected before dying. Higher numbers mean higher render times. Low numbers under “4″ can introduce artifacts or turn some reflections into pure black.
Is the distance of the ambient occlusion shadowing spread in units. This setting should be adjusted in order to achieve realistic results depending on the scale of the objects in the scene. For example a small value is more appropriate for small objects such as toys and larger values for an object such as a house.
There are three possible settings:
Only direct lighting from area lights is included. Indirectly lit areas of the scene will receive no contribution and will be black.
- Ambient Occlusion
Standard ambient occlusion based on shadowing in recessed areas
Produces a higher quality render than Ambient Occlusion but with less overhead than rendering with Path tracing or PMC. It is similar to “brute force” rendering found in other rendering engines. It will not render caustics or other ray traced effects but can be high enough quality for production rendering depending on the scene.
Sets the maximum number of diffuse reflections when GI Mode is set to Diffuse.
Path Termination Power
High values increase render speed but may cause higher noise in dark areas.
Increasing this value will increase the render speed but may introduce low-frequency noise or blotches. Eliminating the blotchy appearance may require minimum of a few hundred or even a few thousand samples per pixel to go away depending on the contents of the scene
Keeps noise patterns static between rendered frames in a sequence when enabled
Controls how many samples are calculated in parallel. Smaller values require less memory to store the samples state but may cause the render to be a bit slower. High values require more memory but can reduce render time. The change in performance depends on the scene and the GPU architecture.
Max Tile Samples
Controls the number of samples per pixel that Octane will render before storing the result in the render buffer. A higher number means that results arrive less often in the film buffer.
Minimize Net Traffic
Distributes only the same tile to the net render slaves until the max samples/pixel has been reached for that tile and only then will the next tile is distributed to slaves when enabled. Work done by local GPUs is not affected by this option. This way a slave can merge all its results into the same cached tile until the master switches to a different tile.
is an option to enable rendering of deep pixel images used for deep image compositing. This is covered in the Deep Image Rendering section of this guide.
Maximum Depth Samples
Is used when deep image rendering is enabled. This sets the maximum number of depth samples per pixel. This is covered in the Deep Image Rendering section of this guide.
Is used when deep image rendering is enabled. The depth samples whose relative depth difference falls below this tolerance value are merged together. This is covered in the Deep Image Rendering section of this guide.
Is used in conjunction with the Alpha Channel setting. It allows the background to be visible in the rendered image while at the same time, keeping the alpha channel.