Questions tagged [sampling]
The sampling tag has no usage guidance.
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Lots of bad samples (below the hemisphere) when sampling the GGX VNDF
I've noticed that my implementation of GGX VNDF sampling produces quite a lot of bad samples (below the hemisphere). When such a sample occurs, I terminate the ray, leading to an immediate black pixel....
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Distance sampling with unbiased transmittance estimators
I'm currently trying some things with transmittance estimators in PBRT and I have implemented the following paper: Unbiased Ray-Marching Transmittance Estimator. This method assumes that two points $x$...
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Measure (or Jacobian) conversion for direction sampling
If in the path tracing use case, I have some sampling strategies to sample a scattering direction in a 2D space ($\theta, \phi$). Of course, I need to convert it to a 3D direction vector (with length ...
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Covering texture surface with ellipses
I am looking for an algorithm (also ideas on possible directions are appreciated) which is able to compute the distribution of ellipses on a 2D surface in order to reach a good degree of covering.
I ...
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Evaluating the Rendering Equation by hand (simple case)
I'm trying to make intuitive sense of the rendering equation and so I'm trying to work out a trivial example by hand, though ultimately I'm just trying to understand how monte carlo importance ...
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How does a path tracer capture light falloff if it deals exclusively with radiance?
My understanding is that path tracers deal with radiance because radiance is constant along a ray. You simply go through and evaluate the light transport equation:
$$
L_o(p, \omega_o) = L_e(p,\...
- 229
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How can I understand the logic of Fast Point Feature Histograms (FPFH) descriptor?
I have been using FPFH features quite a lot in global registration and key-point extraction a lot, I also looked pcl page that tries to explain what it is, but fails to give detail to reader in my ...
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Conditionally sample from texture in shader
I'm building a little 2D graphics library in Rust/WGPU as a means to learn graphics programming. I want to draw an outline around a shape and specify the outline's color. All of my shapes have a ...
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Questions about equi-angular sampling
Equiangular sampling is a sampling method for point (sphere) emitter in scattering medium. While it claims to be very efficient when dealing with point (sphere) emitter in scattering medium (see this ...
- 1,112
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White spots when rendering diffuse material with environment light
I am trying to implement a simple shader. A round ball object is rendered with uniform albedo and I noticed some strange white spots on the outputs.
I perform importance sampling with 512 light ...
- 121
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Confusion about the bias during Monte Carlo integration
I recently stumbled into this question:
Say, for example, we are doing mean-free-path sampling (distance sampling) in a scattering medium and to keep it simple, let's only consider the single ...
- 1,112
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What is the "kernel" in learnopengl SSAO tutorial?
I am currently reading the SSAO tutorial on learnopengl.
In it, there is a "kernel" that has the dimension of 64 and contains ...
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How to properly use scattering coefficient during volumetric path tracing?
The increased radiance during sampling is known by:
$$
L_s = L_e + \sigma_s \int p(w, w')f_p(w, w')dw'
$$
The latter part, which accounts for in-scattering radiance bears a $\sigma_s$ in it.
The ...
- 1,112
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One-sample model Multiple Importance Sampling with balance heuristic
Recently I feel a bit confused about one-sample model MIS. One sample model MIS can be found here in Veach 1997. 9.2.4 The one-sample model, and this one-sample model is widely used in the opensource ...
- 1,112
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Question regarding texture mapping sampling
I am new to computer graphics and have taken up a course in my university on computer graphics. Need help regarding a question as I could not find any relevant resource on the internet so hoping the ...
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