Search found 83 matches

by MohamedSakr
Sat Nov 22, 2014 10:50 pm
Forum: General Development
Topic: understanding different biased algorithms
Replies: 1
Views: 2919

understanding different biased algorithms

this question is mainly posted to understand how the commercial biased render engines work, like vray, mental ray, .. so far the most common approaches are: irradiance map, light cache, photon mapping (+ final gathering) I understand how photon mapping works I understand a little about light cache "...
by MohamedSakr
Mon Nov 10, 2014 10:53 pm
Forum: General Development
Topic: Forward and Backward Probabilities
Replies: 1
Views: 2987

Re: Forward and Backward Probabilities

Moreover pbrt kind of renderers have a bsdf notation in which a pdf is computed as bsdf.pdf(wi, wo) ie. for a given pair of directions, what is the probability of sampling the directions. Would a method definition like bsdf.pdf(wo) make sense i.e just sampling one output direction without any consi...
by MohamedSakr
Wed Oct 29, 2014 5:50 am
Forum: General Development
Topic: Why does all the major renderer use path tracing?
Replies: 2
Views: 3892

Re: Why does all the major renderer use path tracing?

in my personal opinion, path tracing suits commercial rendering for 1 main reason, it is more controllable!!, it can work in very dense scenes "where photon mapping and final gather fails" like hair rendering VCM should give better results, more accurate light transport, but it has 2 main disadvanta...
by MohamedSakr
Sun Oct 19, 2014 10:09 pm
Forum: General Development
Topic: Path tracing accumulation artifacts
Replies: 13
Views: 10967

Re: Path tracing accumulation artifacts

a good RNG is C++ 11 mersenne twister , check https://github.com/SmallVCM/SmallVCM/bl ... rc/rng.hxx
by MohamedSakr
Sun Oct 19, 2014 8:57 pm
Forum: General Development
Topic: Path tracing accumulation artifacts
Replies: 13
Views: 10967

Re: Path tracing accumulation artifacts

hmm, for sure I can see where the errors in the image are, but I'm still concerned about the counter for some reason if the samples are independent, then adding every sample with a different random number seed will give you correct image "so averaging 30k different 1 spp images should be equal to a ...
by MohamedSakr
Sun Oct 19, 2014 8:17 pm
Forum: General Development
Topic: Path tracing accumulation artifacts
Replies: 13
Views: 10967

Re: Path tracing accumulation artifacts

well, test this, an output of 2k * 2k, with 1000 spp, if it generates artifacts then the problem is a false counter somewhere, the data is double or float for sure, but the sample "index" may be false
by MohamedSakr
Sun Oct 19, 2014 8:09 pm
Forum: General Development
Topic: Path tracing accumulation artifacts
Replies: 13
Views: 10967

Re: Path tracing accumulation artifacts

well, I doubt something, so check it first, assuming a counter of integer type which is limited to 2^31, and it loops over the whole image (512 * 512) which is (2^9 * 2^9) , then you will have 2^13 samples per pixel before the counter goes mad (which is 8192 spp) , check this, if it is not the probl...
by MohamedSakr
Sun Oct 19, 2014 7:50 pm
Forum: General Development
Topic: Path tracing accumulation artifacts
Replies: 13
Views: 10967

Re: Path tracing accumulation artifacts

what is the rendered image resolution X , Y
by MohamedSakr
Sun Oct 19, 2014 7:33 pm
Forum: General Development
Topic: question about camera sampling
Replies: 2
Views: 3346

Re: question about camera sampling

thanks a lot Dade :D
by MohamedSakr
Sun Oct 19, 2014 5:30 pm
Forum: General Development
Topic: question about camera sampling
Replies: 2
Views: 3346

question about camera sampling

the question is to extend PBRT I noticed that one of the best samplers is LD sampler, it converges at a very good rate, but it has one drawback!!, it needs a very straight forward algorithm like PT or BDPT, it is unusable with an algorithm like VCM "where the image needs to be integrated as a whole ...