Search found 138 matches

by shiqiu1105
Thu Jul 31, 2014 4:47 am
Forum: General Development
Topic: Total SAH of a BVH
Replies: 11
Views: 11624

Re: Total SAH of a BVH

After a bit of tests the graphicsMan's formulation seems the most coherent with experimental results (i.e. an accelerator structure with better total SAH leads to better performances): // The cost of a node is equal to the probability to hit a child multiplied for the cost of the child SAH(node) = ...
by shiqiu1105
Mon Apr 28, 2014 11:15 pm
Forum: General Development
Topic: Smooth Shading with bidirectional path tracing?
Replies: 7
Views: 8532

Re: Smooth Shading with bidirectional path tracing?

Additionally, Veach says when tracing importance from the light source, local bsdf sampling should happen based on the cosine term of the geometry normal.
I took a quick glance at the mitsuba source code, and it looks to me that it's always sampling based on shading normal too.
by shiqiu1105
Mon Apr 28, 2014 9:57 pm
Forum: General Development
Topic: Smooth Shading with bidirectional path tracing?
Replies: 7
Views: 8532

Re: Smooth Shading with bidirectional path tracing?

I found it. It's in section 5.3. I haven't read the details, if anybody knows what's happening please explain it here too so that we can all learn. I will read it first. What a great thesis, always can learn new things from it. No wonder he won the Oscar... The problem is presented in section 3.7.5...
by shiqiu1105
Tue Apr 22, 2014 11:24 pm
Forum: General Development
Topic: Smooth Shading with bidirectional path tracing?
Replies: 7
Views: 8532

Re: Smooth Shading with bidirectional path tracing?

I found it. It's in section 5.3.
I haven't read the details, if anybody knows what's happening please explain it here too so that we can all learn.

I will read it first.

What a great thesis, always can learn new things from it. No wonder he won the Oscar...
by shiqiu1105
Tue Apr 22, 2014 11:07 pm
Forum: General Development
Topic: Smooth Shading with bidirectional path tracing?
Replies: 7
Views: 8532

Re: Smooth Shading with bidirectional path tracing?

beason wrote:Veach's thesis discusses issues with bidirectional methods and smoothed normals, have you seen that...?
Actually I haven't. Would you mind telling me which chapter in which he talks about that?
by shiqiu1105
Tue Apr 22, 2014 9:07 pm
Forum: General Development
Topic: Smooth Shading with bidirectional path tracing?
Replies: 7
Views: 8532

Smooth Shading with bidirectional path tracing?

Hi folks, I am having trouble producing smooth shading with bidirectional path tracing(BDPT). I am using per vertex normal, and smooth shading can be achieved with path tracing or direct lighting. However, BDPT always results in faceted looking results such as the one below. Notice that even the cau...
by shiqiu1105
Sun Jan 26, 2014 7:28 am
Forum: General Development
Topic: Spatial date structure, kdtree or hash grid.
Replies: 0
Views: 2751

Spatial date structure, kdtree or hash grid.

Hi,

I have noticed that the original photon mapping algorithm uses a kdtree for storing all the photons, where as more recent implementation such as PPM or VCM uses a regular hash grid.

Is there a particular reason except for the ease of implementation? Any comparison?

Thanks.
by shiqiu1105
Thu Jan 16, 2014 3:09 am
Forum: General Development
Topic: Anybody tried implementing Disney's Principled BRDF?
Replies: 11
Views: 12485

Re: Anybody tried implementing Disney's Principled BRDF?

You could select 50/50 between the coating or the base BRDF for reflection using a Russian Roulette. Or you could use a Russian Roulette on the coating microfacet Fresnel reflectance. Both are good. Personally, I select based on the coating Fresnel reflectance. Just wanna make sure, I was asking ab...
by shiqiu1105
Wed Jan 15, 2014 8:49 am
Forum: General Development
Topic: Anybody tried implementing Disney's Principled BRDF?
Replies: 11
Views: 12485

Re: Anybody tried implementing Disney's Principled BRDF?

I read more on this topic and played around with BRDF Explorer, and I think I have a better understanding now. I do have another question. Since the BRDF is the sum of a diffuse component and a specular component modeled by microfacet, when we sample scattering event at the surface, which component ...
by shiqiu1105
Wed Jan 15, 2014 5:11 am
Forum: General Development
Topic: Anybody tried implementing Disney's Principled BRDF?
Replies: 11
Views: 12485

Re: Anybody tried implementing Disney's Principled BRDF?

Also, I read one of your previous post asking about the implementation of the walter 07 rough refraction brdf. And I found their is a reference implementation in the BRDF explorer. I will post it here as well, hope that helps :) analytic # Walter07, w/ GGX # variables go here... # only floats suppor...