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About the implementation of Joint Importance Sampling

Posted: Tue Jan 20, 2015 10:09 pm
by shiqiu1105
Recently I am very interesting in this Joint Importance Sampling: http://www.ci.i.u-tokyo.ac.jp/~hachisuka/jis.pdf

It seems to reduce the variance of volume rendering a lot.
But it looks quite complicated to implement, especially when considering the tabulation in anisotropic phase function.
So is this implemented anywhere, so I could use as reference?

Thanks,

Re: About the implementation of Joint Importance Sampling

Posted: Wed Jan 21, 2015 1:03 am
by ingenious
Unfortunately, there is no public implementation available, due to potential legal problems (the work was done at Disney Research). However, implementing the analytical importance sampling routines is actually quite easy. For this what you really need are the boxed equations in section 5. The tabulated importance sampling routines are a little more involved, but the analytical ones will get you a long way.

Re: About the implementation of Joint Importance Sampling

Posted: Wed Jan 21, 2015 1:12 am
by shiqiu1105
ingenious wrote:Unfortunately, there is no public implementation available, due to potential legal problems (the work was done at Disney Research). However, implementing the analytical importance sampling routines is actually quite easy. For this what you really need are the boxed equations in section 5. The tabulated importance sampling routines are a little more involved, but the analytical ones will get you a long way.
Thank you for the hint ingenious! I will look into it.
One more quick question, 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?

Re: About the implementation of Joint Importance Sampling

Posted: Wed Jan 21, 2015 2:11 am
by ingenious
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.

Re: About the implementation of Joint Importance Sampling

Posted: Thu Jan 22, 2015 1:31 am
by shiqiu1105
ingenious wrote:
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.
Thanks for the info.
Okay I will try to implement the analytic sampling first to do monte carlo subsurface scattering, hopefully post some results.

Been reading about dipole diffuse approximation and just couldn't understand it :(