ompf2.com

Huh, very interesting! So what seems to be happening is that with a -0 direction component, then that dimension's NextCrossingT ends up being negative infinity, and in turn in the ray stepping loop, that dimension is always chosen (wrongly), then it bogus-ly steps along that axis, which is hopeless,...

Sorry for not seeing this sooner! (Haven't been to ompf2 for a while.)

My understanding from the publisher is that it will be (finally) shipping on Nov 25. Sorry for the delay. Hope you enjoy it!

Regards,
Matt

I think I'll make this into one or more switches. Thanks for both your replies. I've experienced precision issues in the past with objects far from the origin, or very strange in scale. It will be good to have a way to test the difference in quality and speed. I think this is an interesting questio...

On page 214, I don't understand the sentence "When working with these error intervals, it’s important to remember that because (1 ± em) terms represent intervals, canceling them incorrect :" On page 219 "then it’s impossible to tell whether it is exactly zero or whether a small positive negative va...

I'm with Koiava on this. Generally I find it much easier to return both sample and pdf as a single entity. It just makes it clear that you need to take the pdf into account. The only exception is when we can sample something uniformly and the pdf is the same for all samples. In some of those cases ...

I took a quick run through the comments in the BDPT integrator but couldn't determine if you have implemented Georgiev's VCM or Hachisuka's near-equivalent. I'm under the impression that these are really important contributions. Are they included? Will they be? How about Markov Chain Monte Carlo? W...

FWIW the third edition of Physically Based Rendering has a new section on numerical robustness issues for ray tracing. There are (we think) some new contributions in it, so we've posted a PDF of that chapter in the hopes that people will take a look at it and see if there are any issues before the b...

In case anyone didn't see it on twitter or on the pbrt mailing lists, I've posted the pbrt-v3 source code: https://github.com/mmp/pbrt-v3. This is the source code that corresponds to the (coming out in Spring 2016) third edition of the book. There are many improvements and new features in this versi...

I've found a couple of ways to deal with this -- As described in the pbrt book, pbrt simply assumes that the ray just grazes the sphere if the intersection fails, and then projects the center of the sphere onto the ray ( code here ). mitsuba moves the origin of the ray closer to the sphere (in fact...