This integrator implements a direct illumination technique that makes use of multiple importance sampling: for each pixel sample, the integrator generates a user-specifiable number of BSDF and emitter samples and combines them using the power heuristic. Usually, the BSDF sampling technique works very well on glossy objects but does badly everywhere else (Figure 33a), while the opposite is true for the emitter sampling technique (Figure 33b). By combining these approaches, one can obtain a rendering technique that works well in both cases (Figure 33c).
The number of samples spent on either technique is configurable, hence it is also possible to turn this plugin into an emitter sampling-only or BSDF sampling-only integrator.
For best results, combine the direct illumination integrator with the low-discrepancy sample generator (ldsampler). Generally, the number of pixel samples of the sample generator can be kept relatively low (e.g. sampleCount=4), whereas the shadingSamples parameter of this integrator should be increased until the variance in the output renderings is acceptable.
• This integrator does not handle participating media or indirect illumination.
- Emitter Samples : integer
- Optional more fine-grained parameter: specifies the number of samples that should be generated using the direct illumination strategies implemented by the scene’s emitters (Default: set to the value of shadingSamples)
- BSDF Samples : integer
- Optional more fine-grained parameter: specifies the number of samples that should be generated using the BSDF sampling strategies implemented by the scene’s surfaces (Default: set to the value of shadingSamples)
- Strict Normals : boolean
- Be strict about potential inconsistencies involving shading normals? See page 154 for details. (Default: no, i.e. false)
- Hide Emitters : boolean
- Hide directly visible emitters? See page 149 for details. (Default: no, i.e. false)