Search found 138 matches

by shiqiu1105
Sat Jul 07, 2012 4:55 pm
Forum: General Development
Topic: About low-discrepancy sequence and image filters in ray trac
Replies: 6
Views: 4597

Re: About low-discrepancy sequence and image filters in ray

Hi, First you can use your 0-2 sequence for a lot of 'sampling' purposes... for sampling BRDF, RR, light, pixels etc... Now, if you sample your pixel, 0-2 sequence allow you to have a good distribution of the samples over one pixel. It is important to have "in average" the right color of the pixel....
by shiqiu1105
Sat Jul 07, 2012 4:53 pm
Forum: General Development
Topic: Tedious bugs in my bidirectional path tracer.
Replies: 10
Views: 10678

Re: Tedious bugs in my bidirectional path tracer.

If you're trying to do multiple importance sampling with balance/power heuristic weighting, then your weights are definitely wrong. Try first with uniform weights to see whether the path contributions are computed correctly. That is, set the weight for each path to 1 / number_of_possible_ways_to_ge...
by shiqiu1105
Thu Jul 05, 2012 8:37 am
Forum: General Development
Topic: About low-discrepancy sequence and image filters in ray trac
Replies: 6
Views: 4597

About low-discrepancy sequence and image filters in ray trac

Hi guys, I have been reading pbrt and writing my own ray tracer. But I have bumped into a question though. In pbrt, it implements a low-discrepancy sampler which use the 0-2 sequence to generate high quality samples. It also states that when low-discrepancy pattern is used, the best image result com...
by shiqiu1105
Thu Jul 05, 2012 5:04 am
Forum: General Development
Topic: Tedious bugs in my bidirectional path tracer.
Replies: 10
Views: 10678

Tedious bugs in my bidirectional path tracer.

Hi guys, I have been trying to create my bidirectional path tracer for a long while. But there were always bugs which I was having a hard time debugging! The result image is down below. My bidir path tracer generates noiser images than my path tracer when the same amount of samples are used :( Bidir...
by shiqiu1105
Thu Jul 05, 2012 4:56 am
Forum: General Development
Topic: Discussion about photon mapping.
Replies: 5
Views: 4328

Discussion about photon mapping.

Lately I have been trying to add photon mapper to my own ray tracer. I have been taking pbrt and Jensen's book <Realistic Image Synthesis using Photon Mapping> as my primary references. In the progress of reading, I have generated a few questions. 1. I have noticed that pbrt's PM implementation diff...
by shiqiu1105
Fri Jun 08, 2012 5:34 am
Forum: General Development
Topic: Why I cannot get the specular reflection right with mesh?
Replies: 7
Views: 6924

Re: Why I cannot get the specular reflection right with mesh

I still don't know what's the cause.
However, when I use path tracing with over 1000 spp, the result seems right. @_@
glossy.jpg
glossy.jpg (89.22 KiB) Viewed 6814 times
by shiqiu1105
Thu Jun 07, 2012 5:39 pm
Forum: General Development
Topic: Why I cannot get the specular reflection right with mesh?
Replies: 7
Views: 6924

Re: Why I cannot get the specular reflection right with mesh

Thanks guys, for your kind help! I have found the problem, well, to some extent. I miscalculated the surface tangent vectors, which lead to false transformation to BRDF space, where I perform vector reflection and refraction. I now seem to get the correct reflection, as here glas2.jpg But as to the ...
by shiqiu1105
Wed Jun 06, 2012 5:18 pm
Forum: General Development
Topic: Why I cannot get the specular reflection right with mesh?
Replies: 7
Views: 6924

Why I cannot get the specular reflection right with mesh?

Hi all, I am having troubling rendering correct specular reflection and refraction with triangle meshes. I can render the correct reflection and refraction with other implicit surface like spheres though. The reflected color would appear as if they are not continuous surfaces, but rather seperated t...