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1500 questions
3
votes
1 answer
Sampling the light vs. sampling the BRDF: difference in intensity
(possible duplicate)
I'm trying to implement multiple importance sampling, as described in the PBRT book (no bouncing yet, I want to make MIS work first).
What my problem is, that while the BRDF sampling looks okay, the light sampling is much dimmer…
Asylum
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3
votes
1 answer
Ray vs AABB algorithm that also gives which side was hit?
There are plenty of well-known algorithms for determining if a ray hit an Axis-Aligned Bounding Box (AABB), like Andrew Woo's covered in a response here.
Using exit = origin + (dir * tMax) will give you the exact position of exit using distance…
Tyler Shellberg
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- 10
3
votes
1 answer
Intrepret path/light tracing by rewriting light transport equation
Given the rendering equation:
$$
L_o(x, \theta_o) = L_e(x, \theta_o) + \int_{\Omega} \! f(x,\theta_i,\theta_o) L_i(x,\theta_i) \cos(\theta_i, \theta_o) \, \mathrm{d} \theta_i.
$$
Rewriting it using linear operator $F$, as:
$$
L_o = L_e + F \circ…
WDC
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3
votes
1 answer
What is a "light source" in global illumination?
In the context of global illumination and the scattering equation, do we need to understand "light sources" as surfaces with a "purely emissive" material on which no scattering is present?
In contrast, any surface in the scene geometry could be…
0xbadf00d
- 203
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- 7
3
votes
1 answer
How can I raycast with chunks?
I am attempting to implement chunks/octrees to speed up my render times. However, sometimes the walls show horizontal or vertical lines (rays hitting the inside of voxels?) or some blocks disappear altogether, although sometimes everything renders…
Russell356
- 31
- 3
3
votes
1 answer
Implementing the example of Walter et al. (2007) paper
As the title suggests I'm trying to implement the last images of the "Microfacet Models for Refraction through Rough Surfaces" Paper by Walter et al. in OpenGL
I "think" (I had to put that into quotation marks) I know how the microfacet model should…
Clutterhead
- 41
- 3
3
votes
0 answers
How to calculate subsurface scattering weights for fast skin shading
This question is in reference to the method described in ShaderX7 section 2.4 "Fast Skin Shading" by Hable et. al. The part I do not understand is how they derived the weights for the individual samples. They describe the process only very briefly…
elramino
- 31
- 3
3
votes
1 answer
Can D3D12 resource barriers be used to synchronize between the compute and 3D engine?
What is the best way to synchronize resource access between the (async) compute engine and the 3d engine (aka. direct engine) in D3D 12?
I found this paragraph about multi-engine synchronization on MSDN but it's not very detailed.
You can certainly…
George
- 61
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3
votes
1 answer
Is there a way to perform calculations of Mandelbrot set using only integer numbers?
I would like to create program in JavaScript (JS) which draws Mandelbrot set with arbitrary precision (zoom). In JS there is build in integer type BigInt which support simple operations like +,*,/,power on arbitrary precision integer numbers. JS not…
Kamil Kiełczewski
- 155
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- 6
3
votes
0 answers
Projective Texture / Shadow Mapping -- Why is the perspective division performed in the fragment shader?
I've just worked my way through this OpenGL shadow mapping tutorial.
While I understand the basic algorithm, one thing puzzles me:
During the 2nd render pass all vertices are transformed into the clip space of the light source. This is done by…
rapunzel
- 31
- 1
3
votes
3 answers
Latency difference between texture copy on GPU vs CPU?
Does anyone happen to know the latency difference between copying a texture on cpu (using, say, memcpy) compared to gpu (using, say, CopyResource)? I would do a perf test myself, but I'm not actually sure how to do the trace for the CopyResource. A…
Kerastan
- 31
- 2
3
votes
0 answers
Irradiance field approximation with black probes
I'm posting here after some time searching the Internet and reading presentations and papers, to find out the best options to solve the problem I have.
I'm implementing irradiance field with spherical harmonics for diffuse global illumination. As…
Alex
- 31
- 2
3
votes
1 answer
What are the type constants that the documentation for glGetProgramResourceiv() refers to?
Quoting the Khronos OpenGL documentation pages for the glGetProgramResourceiv() function:
For the property GL_TYPE, a single integer identifying the type of an
active variable is written to params. The integer returned is one of
the values…
BadZen
- 143
- 5
3
votes
1 answer
Douglas-Peuker and equal distances
I have a polyline and I want to simplify it with Douglas-Peucker. It's an easy algorithm, but what if there are points with the same distance. What point should I select? Is there a reasonable solution?
rr84
- 105
- 4
3
votes
1 answer
Non least squares formulation to fit catmull rom spline
I have a set of unordered points that I'm getting from an image attached. I'd like to simply fit a parametrized curve such as a catmull-rom curve to with n control points (n = 4 to 10, and can be assumed to be known).
I've explored ways of doing…
dev_nut
- 143
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