diff options
| author | Lukas Stockner <lukas.stockner@freenet.de> | 2016-10-30 00:47:30 +0300 |
|---|---|---|
| committer | Lukas Stockner <lukas.stockner@freenet.de> | 2016-10-30 13:31:28 +0300 |
| commit | 26bf230920cb9ca0aa9626430169967f9e120482 (patch) | |
| tree | 266e7e0939a6471db8af7086635cc4e914c85b06 /intern/cycles/kernel/kernel_emission.h | |
| parent | ce785868a56a1446750f5af1779f7623ca462ec2 (diff) | |
Cycles: Add optional probabilistic termination of light samples based on their expected contribution
In scenes with many lights, some of them might have a very small contribution to some pixels, but the shadow rays are traced anyways.
To avoid that, this patch adds probabilistic termination to light samples - if the contribution before checking for shadowing is below a user-defined threshold, the sample will be discarded with probability (1 - (contribution / threshold)) and otherwise kept, but weighted more to remain unbiased.
This is the same approach that's also used in path termination based on length.
Note that the rendering remains unbiased with this option, it just adds a bit of noise - but if the setting is used moderately, the speedup gained easily outweighs the additional noise.
Reviewers: #cycles
Subscribers: sergey, brecht
Differential Revision: https://developer.blender.org/D2217
Diffstat (limited to 'intern/cycles/kernel/kernel_emission.h')
| -rw-r--r-- | intern/cycles/kernel/kernel_emission.h | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/intern/cycles/kernel/kernel_emission.h b/intern/cycles/kernel/kernel_emission.h index 9e4a631b998..8c7c651a053 100644 --- a/intern/cycles/kernel/kernel_emission.h +++ b/intern/cycles/kernel/kernel_emission.h @@ -94,7 +94,8 @@ ccl_device_noinline bool direct_emission(KernelGlobals *kg, ccl_addr_space PathState *state, Ray *ray, BsdfEval *eval, - bool *is_lamp) + bool *is_lamp, + float rand_terminate) { if(ls->pdf == 0.0f) return false; @@ -134,7 +135,7 @@ ccl_device_noinline bool direct_emission(KernelGlobals *kg, shader_bsdf_eval(kg, sd, ls->D, eval, ls->pdf, ls->shader & SHADER_USE_MIS); #endif - bsdf_eval_mul(eval, light_eval/ls->pdf); + bsdf_eval_mul3(eval, light_eval/ls->pdf); #ifdef __PASSES__ /* use visibility flag to skip lights */ @@ -155,6 +156,16 @@ ccl_device_noinline bool direct_emission(KernelGlobals *kg, if(bsdf_eval_is_zero(eval)) return false; + if(kernel_data.integrator.light_inv_rr_threshold > 0.0f) { + float probability = max3(bsdf_eval_sum(eval)) * kernel_data.integrator.light_inv_rr_threshold; + if(probability < 1.0f) { + if(rand_terminate >= probability) { + return false; + } + bsdf_eval_mul(eval, 1.0f / probability); + } + } + if(ls->shader & SHADER_CAST_SHADOW) { /* setup ray */ bool transmit = (dot(ccl_fetch(sd, Ng), ls->D) < 0.0f); |