## Search found 20 matches

Mon Jul 18, 2016 9:14 pm
Forum: General Development
Topic: Ideal Specular BTDF
Replies: 2
Views: 6847

### Re: Ideal Specular BTDF

Hello The BTDF can be derived as follows. For incoming light L_i that hits a specular material with BRDF (F), L_o is the exitant radiance L_o = F x L_i. Since in path tracing, we generally come from the outgoing direction and sample the incoming direction, for w_o, w_i is the mirror direction. The d...
Mon Feb 22, 2016 6:18 pm
Forum: General Development
Topic: Sweep of a solid angle
Replies: 2
Views: 3937

### Sweep of a solid angle

Hello All I'm stuck with a problem that basically boils down to analytically computing the total sweep of the solid angle subtended at a point. Assume that there is a quad that moves along a direction vector say u, and for each position on the direction u, I would like to compute the solid angle sub...
Mon Feb 23, 2015 10:20 am
Forum: Visuals, Tools, Demos & Sources
Topic: Glitch Pictures anyone?
Replies: 81
Views: 123612

### Re: Glitch Pictures anyone?

I really have no idea what is going on but this image kind of looks like disco lamps in full glow.
Tue Jan 20, 2015 2:33 pm
Forum: General Development
Topic: Pbrt 2: How does LookAt work?
Replies: 1
Views: 3435

### Re: Pbrt 2: How does LookAt work?

Hi

PerspectiveCamera constructor accepts a transform of the form camToWorld whereas the lookat computes worldToCam as the main transform. I guess you have to invert this transform and send it to PerspectiveCamera.
Fri Jan 02, 2015 6:18 am
Forum: General Development
Topic: Questions on BDPT and Sampling
Replies: 3
Views: 4033

### Re: Questions on BDPT and Sampling

Hello Sorry for the confusion. I think I messed up the description and the table. Let me make myself clear as to what my actual doubt is. In Veach's thesis, each pixel's sample contribution is given by sum of light carrying paths of increasing lengths from 1 - infinity. Each component in the sum is ...
Wed Dec 31, 2014 5:46 am
Forum: General Development
Topic: Questions on BDPT and Sampling
Replies: 3
Views: 4033

### Questions on BDPT and Sampling

Hello all I've got a question with regards to BDPT and sampling. In BDPT in order to efficiently generate paths, we do a correlated path sampling scheme by connecting all vertices of the camera path to all the vertices of the light path. Assume the length of eye path as N_E and the light path as N_L...
Tue Nov 25, 2014 6:32 pm
Forum: General Development
Topic: Question about Bottom-up traversal used in LBVH and TRBVH
Replies: 14
Views: 10067

### Re: Question about Bottom-up traversal used in LBVH and TRBV

Hi The hardware guarantees that increments will happen in atomic fashion as in serially and hence the return values would be unique (the function would not return till the increment happens). However I feel that the while loop condition is not a guarantee to prevent race condition as you will be hav...
Tue Nov 25, 2014 1:44 pm
Forum: General Development
Topic: Question about Bottom-up traversal used in LBVH and TRBVH
Replies: 14
Views: 10067

### Re: Question about Bottom-up traversal used in LBVH and TRBV

Hi Basically you'd be experiencing a race condition if you were to assume that results of A+B is computed by the time C gets to root node. Hypothetically such a situation is valid only when all threads execute in step which is never guaranteed at hardware level. You must use some synchronization pri...
Mon Nov 10, 2014 11:00 am
Forum: General Development
Topic: Forward and Backward Probabilities
Replies: 1
Views: 3023

### Forward and Backward Probabilities

Hello All I've been trying to understand light transport in Veach's path integral framework. With respect to computing the pdf of the random walk path, we normally do a multiplication of all the path vertices probabilities wrto area .ie. p(x0).p(x1)...p(x_k). But normally we go for an incremental co...
Mon Sep 29, 2014 3:37 am
Forum: General Development
Topic: questions about displacement, normal and bump
Replies: 4
Views: 4023

### Re: questions about displacement, normal and bump

imho bump mapping is the same as normal mapping. Wikipedia suggests that 'Normal mapping is the most common variation of bump mapping used' to quote.