Search found 138 matches

by shiqiu1105
Fri Jan 25, 2013 7:30 pm
Forum: General Development
Topic: Question about BDPT with pinhole camera model.
Replies: 16
Views: 10386

Question about BDPT with pinhole camera model.

Hi all,

I want to know is it possible to implement BDPT without explicitly modeling a intersectable camera len in the scene? Since it's nasty and carries little contribution.

How do I adjust the MIS weight of the first camera node then?

Or is it impossible to be implemented this way?
by shiqiu1105
Fri Jan 25, 2013 7:27 pm
Forum: General Development
Topic: General questions about GPU ray tracing.
Replies: 5
Views: 4496

General questions about GPU ray tracing.

I have been trying to implement a GPU ray tracer for a while, but always had a few confusions in mind. From my own study, it looks to me that the most straight forward to support global illumination on the GPU is to use Path Tracing, in a progressive way, if possible. However, I don't know how to ge...
by shiqiu1105
Wed Dec 12, 2012 4:36 am
Forum: General Development
Topic: Questions about Multiple Importance Sampling in BDPT
Replies: 1
Views: 2631

Questions about Multiple Importance Sampling in BDPT

I have been trying to add Multiple Importance Sampling to weigh the paths in my bidirectional path tracer for 12 months and failed. This is the post I posted 4 months ago. And the problem is still there... http://ompf2.com/viewtopic.php?f=3&t=512 Until recently I found where I did wrong, but still d...
by shiqiu1105
Wed Dec 12, 2012 3:57 am
Forum: General Development
Topic: Questions about developing GPU Ray tracer.
Replies: 1
Views: 2307

Questions about developing GPU Ray tracer.

Hi all, I have experience with making CPU ray tracer. And right now I am planning to write a GPU ray tracer that is interactive. But I have a lot of questions, some of them are very basic. 1. Where should the primitives be stored, I am using CUDA, so should they be placed in global memory? constant ...
by shiqiu1105
Thu Jul 19, 2012 3:47 pm
Forum: General Development
Topic: Discussion on GPU ray tracing
Replies: 3
Views: 3631

Discussion on GPU ray tracing

HI folks, I am trying to write a basic ray tracer with CUDA. What I have implemented now is simply 1 sample per pixel, and each sample is assigned to a cuda thread. And each thread traces it's own ray. I am writing to ask more advanced and efficient ways of doing this. For example, what's the best t...
by shiqiu1105
Mon Jul 09, 2012 12:06 pm
Forum: General Development
Topic: Tedious bugs in my bidirectional path tracer.
Replies: 10
Views: 10683

Re: Tedious bugs in my bidirectional path tracer.

Are you absolutely, 100 percent sure that the paths in both images have maximum length of 5 and that you don't miss some possible paths? When connecting eye and light sub-paths, you need to watch out for the length of the resulting full path! And image without MIS can be slightly darker, but *only*...
by shiqiu1105
Mon Jul 09, 2012 2:14 am
Forum: General Development
Topic: Tedious bugs in my bidirectional path tracer.
Replies: 10
Views: 10683

Re: Tedious bugs in my bidirectional path tracer.

Are you absolutely, 100 percent sure that the paths in both images have maximum length of 5 and that you don't miss some possible paths? When connecting eye and light sub-paths, you need to watch out for the length of the resulting full path! And image without MIS can be slightly darker, but *only*...
by shiqiu1105
Sun Jul 08, 2012 3:21 pm
Forum: General Development
Topic: Discussion about photon mapping.
Replies: 5
Views: 4331

Re: Discussion about photon mapping.

A regular diffuse area light will have a uniform distribution. However, due to the projected solid angle calculation, there is a cosine term, which means that you'll converge faster if you draw samples on a cosine distribution. Okay, I guess I will modify that. I wonder why pbrt doesn't do this tho...
by shiqiu1105
Sun Jul 08, 2012 6:35 am
Forum: General Development
Topic: Discussion about photon mapping.
Replies: 5
Views: 4331

Re: Discussion about photon mapping.

Whether you are better off shooting photons based on uniform or diffuse depends on your emission distribution. Choose what is right for your light sources. I don't know about PBRT's implementation, as I haven't read that chapter, but when I implemented photon mapping a (long) while back, I used Jen...
by shiqiu1105
Sun Jul 08, 2012 6:30 am
Forum: General Development
Topic: Tedious bugs in my bidirectional path tracer.
Replies: 10
Views: 10683

Re: Tedious bugs in my bidirectional path tracer.

How do you know if two images have the same overall brightness? I am now trying the unform-weighted bidir path tracing, and I am posting the result. The bidirectional version has A LOT fireflies, and seems to be a little brighter, which I am not sure is caused by the uniform weights or bugs... Do y...