This plugin implements stochastic progressive photon mapping by Hachisuka et al. . This algorithm is an extension of progressive photon mapping (ppm) that improves convergence when rendering scenes involving depth-of-field, motion blur, and glossy reflections.
Note that the implementation of sppm in Mitsuba ignores the sampler configuration—hence, the usual steps of choosing a sample generator and a desired number of samples per pixel are not necessary.
As with ppm, once started, the rendering process continues indefinitely until it is manually stopped.
• Due to the data dependencies of this algorithm, the parallelization is limited to to the local machine (i.e. cluster-wide renderings are not implemented)
• This integrator does not handle participating media
• This integrator does not currently work with subsurface scattering models.
- Max. path depth : integer
- Specifies the longest path depth in the generated output image (where -1 corresponds to ∞). A value of 1 will only render directly visible light sources. 2 will lead to singlebounce (direct-only) illumination, and so on. (Default: -1 -> 24 @ blender)
- Russian roulette starting depth : integer
- Specifies the minimum path depth, after which the implementation will start to use the “russian roulette” path termination criterion. (Default: 5 -> 10 @ blender)
- Work unit granularity : integer
- Granularity of photon tracing work units for the purpose of parallelization (in # of shot particles) (Default: 0, i.e. decide automatically)
- Photon Count : integer
- Number of photons to be shot per iteration (Default: 250000)
- Initial Radius : float
- Initial radius of gather points inworld space units. (Default: 0, i.e. decide automatically)
- Radius Alpha : float
- Radius reduction parameter alpha fromthe paper (Default: 0.7)
- maxPasses : integer (blender にはない？)
- Maximum number of passes to render (where -1 corresponds to rendering until stopped manually). (Default: -1)