Search found 58 matches

by shocker_0x15
Wed Feb 22, 2017 5:15 am
Forum: General Development
Topic: Multi-wavelength free path sampling using ratio tracking
Replies: 0
Views: 281

Multi-wavelength free path sampling using ratio tracking

Hi, I'm curious about whether using ratio tracking for estimating Monte Carlo constribution (f(x) / p(x), not transmittance) with delta tracking for heterogeneous media is unbiased. We can get a MC contribution of free path sampling by delta tracking for a wavelength used for the procedure. There is...
by shocker_0x15
Mon Jan 09, 2017 5:15 pm
Forum: General Development
Topic: Volumetric Pathtracing / Small UPBP
Replies: 4
Views: 8496

Re: Volumetric Pathtracing / Small UPBP

Sorry to be late. This procedure implicitly includes selection between the two terms with probability. select the case 1 with probability P_s select the case 2 with probability 1 - P_s P_s is a probability to perform evaluation on surface. case 1: immediately evaluate the attenuated radiance leaving...
by shocker_0x15
Thu Dec 15, 2016 1:55 am
Forum: General Development
Topic: Volumetric Pathtracing / Small UPBP
Replies: 4
Views: 8496

Re: Volumetric Pathtracing / Small UPBP

Hi, As you know, volume light transport equation consists of two terms where the one is attenuated light L_s leaving a surface and the other is "the integral of" light gain L_a due to in-scattering and emission. L_i = T * L_s + int T * L_a ds * L_a is volumetric emission and in-scattering ...
by shocker_0x15
Mon Dec 12, 2016 2:16 am
Forum: General Development
Topic: Multiple Textures CUDA/OpenCL
Replies: 8
Views: 8261

Re: Multiple Textures CUDA/OpenCL

Thank you ultimatemau.
It is exactly what I want to say.
by shocker_0x15
Thu Dec 08, 2016 1:44 am
Forum: General Development
Topic: Multiple Textures CUDA/OpenCL
Replies: 8
Views: 8261

Re: Multiple Textures CUDA/OpenCL

Hi, If we create a global illumination renderer like path tracing, using a dedicated texture type seems not plausible because we cannot know which texture is used and a lot of textures should be bound into kernel. In my OpenCL renderer, I used a single uchar* argument of a kernel as a pointer to tex...
by shocker_0x15
Fri Aug 12, 2016 7:54 am
Forum: General Development
Topic: Ideal Specular BTDF
Replies: 2
Views: 3235

Re: Ideal Specular BTDF

Thanks sriravic and sorry to be late :) I can understand why the ideal specular BRDF/BTDF should have the cosine dividing. BRDF has reciprocity, so it has the same value if it takes swapped directions: f_r(w_i, w_o) = f_r(w_o, w_i) It is easy to confirm the ideal specular BRDF obey this relation. BT...
by shocker_0x15
Tue May 24, 2016 5:34 am
Forum: General Development
Topic: Ideal Specular BTDF
Replies: 2
Views: 3235

Ideal Specular BTDF

Hi, I have had a question for a long time about ideal specular BTDF (BRDF). Ideal specular BRDF and BTDF are: ⋅ f_r(w_i, w_o) = F(theta_i) * delta(w_o - R(w_i, n)) / |cos(theta_i)| ⋅ f_t(w_i, w_o) = (eta_o / eta_i)^2 * (1 - F(theta_i)) * delta(w_o - T(w_i, n)) / |cos(theta_i)| wh...
by shocker_0x15
Tue May 24, 2016 5:04 am
Forum: General Development
Topic: A question about BSSRDF generalized to rough surface
Replies: 3
Views: 1134

Re: A question about BSSRDF generalized to rough surface

Thank you for your reply. And the diffuse Fresnel transmittance is no more than approximation to specular Fresnel transmittance from all directions. The original BSSRDF seems to use "directional" Fresnel transmittance not diffuse one. Is it natural that substituting the ideal specular BTDF...
by shocker_0x15
Sun May 01, 2016 10:57 am
Forum: General Development
Topic: A question about BSSRDF generalized to rough surface
Replies: 3
Views: 1134

Re: A question about BSSRDF generalized to rough surface

Conventions for symbols I used are convention.png I got the following if I substitute an ideal specular BTDF to the equation I posted. substitute_ideal_specular.png However this slightly differs from the original one. (The latter Fresnel term is the same to F(eta, wo), therefore the problem is the f...
by shocker_0x15
Sun May 01, 2016 10:53 am
Forum: General Development
Topic: A question about BSSRDF generalized to rough surface
Replies: 3
Views: 1134

A question about BSSRDF generalized to rough surface

Hi, Now I try to implement SSS feature in my renderer using BSSRDF. I have started with "A Practical Model for Subsurface Light Transport" and Donner's thesis "Towards Realistic Image Synthesis of Scattering Materials". They say that the diffuse component of BSSRDF for smooth sur...

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