Search found 9 matches

by mattpharr
Tue Nov 22, 2016 1:37 am
Forum: General Development
Topic: pbrt-v2 grid code traversal problem
Replies: 2
Views: 11801

Re: pbrt-v2 grid code traversal problem

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,...
by mattpharr
Tue Nov 22, 2016 1:17 am
Forum: Links & Papers
Topic: Physically Based Rendering 3E
Replies: 2
Views: 16744

Re: Physically Based Rendering 3E

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
by mattpharr
Fri Oct 16, 2015 4:00 pm
Forum: General Development
Topic: Float versus double
Replies: 12
Views: 12028

Re: Float versus double

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...
by mattpharr
Thu Jul 16, 2015 12:13 am
Forum: General Development
Topic: pbrt-v3 source code now available
Replies: 23
Views: 19600

Re: pbrt-v3 source code now available

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 posit...
by mattpharr
Thu Jul 16, 2015 12:12 am
Forum: General Development
Topic: pbrt-v3 source code now available
Replies: 23
Views: 19600

Re: pbrt-v3 source code now available

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 ...
by mattpharr
Thu Jul 16, 2015 12:09 am
Forum: General Development
Topic: pbrt-v3 source code now available
Replies: 23
Views: 19600

Re: pbrt-v3 source code now available

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...
by mattpharr
Tue Jun 30, 2015 5:15 am
Forum: Links & Papers
Topic: Looking for robust ray offsets
Replies: 2
Views: 5594

Re: Looking for robust ray offsets

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...
by mattpharr
Tue Jun 30, 2015 5:13 am
Forum: General Development
Topic: pbrt-v3 source code now available
Replies: 23
Views: 19600

pbrt-v3 source code now available

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...
by mattpharr
Tue Jun 30, 2015 5:11 am
Forum: General Development
Topic: A better way to sample a sphere (w.r.t. solid angle)
Replies: 16
Views: 17206

Re: A better way to sample a sphere (w.r.t. solid angle)

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...

Go to advanced search