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by ingenious
Fri Nov 11, 2016 11:03 pm
Forum: Links & Papers
Topic: Robust Light Transport Simulation via Metropolised Bidirectional Estimators
Replies: 5
Views: 8759

Re: Robust Light Transport Simulation via Metropolised Bidirectional Estimators

I think this is the answer. Given an endpoint on the eye subpath one can employ proper importance sampling on the light source for NEE (for example for spherical lights or environment map it is possible cull the part of the light source where the eye subpath can't see). It also reduces the correlat...
by ingenious
Wed Jun 15, 2016 12:08 pm
Forum: Visuals
Topic: GPU VCM
Replies: 30
Views: 22900

Re: GPU VCM

Thanks, very interesting!
by ingenious
Wed Jun 15, 2016 10:46 am
Forum: Visuals
Topic: GPU VCM
Replies: 30
Views: 22900

Re: GPU VCM

If I use a radius close to the projected pixel size the number of photons arriving per pixel is going to be low, right? That would probably lead to fireflies for quite a bit longer than the first 16-32 samples, which is the time frame I'm trying to optimize for. Indeed, this will inevitably increas...
by ingenious
Tue Jun 14, 2016 11:00 pm
Forum: Visuals
Topic: GPU VCM
Replies: 30
Views: 22900

Re: GPU VCM

Nice videos! I'd recommend using a smaller radius for vertex merging, something close to the projected pixel size, which would remove the nasty photon splotches. With VCM you can most often get away with using a small radius (unlike in PPM), because in the areas where merging is important the photon...
by ingenious
Thu May 05, 2016 11:41 pm
Forum: General Development
Topic: Regarding directional dipole
Replies: 4
Views: 4648

Re: Regarding directional dipole

If I remember correctly, the dirpole model includes single scattering, so in theory its result should be closer to the path traced reference. Can you actually please post that reference here for completeness?
by ingenious
Thu Mar 17, 2016 11:24 am
Forum: General Development
Topic: Energy conservation vs. energy normalization
Replies: 4
Views: 4952

Re: Energy conservation vs. energy normalization

shocker_0x15 , he does not have a problem with BRDF values going above one, and he actually computes a proper normalization factor by integrating the unnormalized BRDF. Indeed, in practice you will lose energy because when the reflected ray is not at normal direction, parts of the BRDF go below the...
by ingenious
Sun Sep 20, 2015 6:28 pm
Forum: My First...
Topic: BDPT implementation issues
Replies: 4
Views: 6555

Re: BDPT implementation issues

p1L = pdf of point on light source. Assuming the light source is a sphere with radius r and it radiates uniformly, this would be (1 / 4 * PI). Correct. Though keep in mind that the pdfs you need to evaluate do not necessarily directly correspond to the physical properties of the materials and light...
by ingenious
Mon Sep 14, 2015 10:47 am
Forum: My First...
Topic: BDPT implementation issues
Replies: 4
Views: 6555

Re: BDPT implementation issues

Watch out the notation -- P and p_i are different quantities (in upper and lower case respectively). P(y_i) denotes the probability of sampling vertex y_i w.r.t. surface area. Then, p_i is a quantity that Veach defines to "represent the probabilities for the first i vertices...", which are...
by ingenious
Wed Aug 26, 2015 2:26 pm
Forum: Links & Papers
Topic: Light path classification
Replies: 3
Views: 16894

Re: Light path classification

The only type of light paths that a forward path tracer cannot sample is E(D|G)*S+L, where L is a light source whose definition involves a delta distribution, either in the directional emission or the positional. Examples are point lights and directional lights. Such paths can be described using Vea...
by ingenious
Wed Jan 21, 2015 2:11 am
Forum: General Development
Topic: About the implementation of Joint Importance Sampling
Replies: 4
Views: 3369

Re: About the implementation of Joint Importance Sampling

shiqiu1105 wrote:I understand that BDPT is one of the estimators used in your latest UPBP, so is this joint sampling used in that framework as well?


The joint importance sampling techniques weren't actually used there (couldn't do it on time), but they can certainly be added to improve sampling.

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