Path Tracing is best used for realistic results. The render times are higher than Direct Lighting but the results can be photorealistic. It can have some difficulties with small light sources and proper caustics.
Maximum Depth (maxdepth)
The maximum number of times a ray can bounce/reflect/refract in a surface. Higher amounts mean also higher render time but more realistic results. For outdoor renders a good setting is around 4 maxdepth. For lighting interior with natural light (the sun and the sky) you will need higher settings such as 8 or higher. While high values are possible, in reality rays will not usually go beyond 16 ray depth.
Russian Roulette Probability (rrprob)
The RRprob is the probability of terminating the path randomly during raytracing. This value should be left as the default. A value of zero allows OctaneRender™ to determine the value.
Ray Epsilon (rayepsilon)
The ray epsilon is the distance to offset new rays so they don’t intersect with the originating geometry. This value should be left as the default.
Maximum Samples (maxsamples)
This 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.
Filter Size (filtersize)
This sets the pixel size for filter for the render. This can improve aliasing artifacts in the render. If the filter is set too high, the image can become blurry.
Alpha ChannelA greyscale image used to determine which areas of a texture map are opaque and which areas are transparent. (alphachannel)
This option removes the background and renders it as transparant (zero alpha). This can be useful if the user wants to composite the render over another image and does not want the background to be present.
Keep Environment (keep_environment)
This option is used in conjuction with the Alpha Channel setting. It allows the background to be rendered with zero alpha but is still visible in the final render. This allows even further flexiblity in compositing images.
Alpha Shadows (alphashadows)
If alpha maps are used in the scene, this setting controls whether the shadows will calculated from the mesh geometry or from the alpha map.