12
votes
Accepted
What explains the high specularity of metals?
Warning: I am not a physicist.
As Dan Hulme already explained, light can't travel through metals, so dealing with IOR is a lot more... complex. I will answer why that happens and how to calculate the ...
- 546
6
votes
What explains the high specularity of metals?
Look at the refractive index of several metals. They are all complex numbers and the math does work out when you put this into the fresnel equation: you get the expected high reflectivity at all ...
- 1,585
4
votes
Accepted
Do we have to adapt what we know from physics to forwards vs. backwards ray-tracing?
TLDR: As long as you write your algorithms correctly you are approximating the same integral regardless whether you trace forward or backward. It's just approximations of different reformulations of ...
- 2,561
3
votes
2D metaballs with marching squares and linear interpolation
as promised, here my answer to your question.
As I can't follow your code completely (I spend most of my time implementing my code :D ) I can only explain to you what the last step is.
So why do we ...
- 195
3
votes
Accepted
Why is the approximation valid, in the formula provided by Brian Karis?
"the information that $f(l_k,v)$ carries is low-frequency enough": As IneQuation explains, low-frequency was used to refer to the detail of the brdf function. I did actually mean that $f_r$ was low ...
- 588
3
votes
Understanding lighting for physically based rendering
Referring to the answer that lightxbulb already gave, you can find a very in-depth explanation of the physics of light and their simulation in the thesis of Eric Veach named "Robust Monte Carlo ...
- 131
3
votes
Understanding lighting for physically based rendering
Here you have a full repository with a lot of papers about light transport. There's also a folder named 'theory' where you can get both intro and advanced refs regard light physics. And much more. I'm ...
- 302
3
votes
Accepted
Rendering Hypercentric Perspective
You can approximate the view of a hypercentric camera with an ordinary 3D perspective camera if you are able to manipulate the projection matrix, and/or reverse the direction of the depth test.
In a ...
- 25.3k
2
votes
Blackbody curve to floating RGB
The Open Shading Language has a complete implementation which is based on this source code from Color Rendering of Spectra by John Walker, according to the comments. I can't vouch for its theoretical ...
- 1,585
2
votes
What explains the high specularity of metals?
The refractive index is related to the speed at which light travels through the medium, and only applies to materials which are at least partially transparent. Metals are electrically conductive, so ...
- 6,880
2
votes
Rendering Hypercentric Perspective
The answer is yes.
You need 2 things:
View space coordinates of the object
Projection function for the hypercentric perspective camera.
The second one can be found in here.
The overview of the model
...
- 446
1
vote
Can raytracing be used to determine a certain gas distribution in a real planet's atmosphere?
I think it is possible via differentiable rendering techniques, but you are going to need some data for it. Like when you have your model, for example, a spherical heterogeneous scattering medium ...
- 1,302
1
vote
Prove radiance contributions of deeper paths fade away
If you are asking whether:
$$
\int fr(...) cos\theta_1Le_1 > \int fr(...)cos\theta_1 fr(...)cos\theta_2 Le_2
$$
(simplified terms from the render equation you posted above), I don't think you ...
- 529
1
vote
Accepted
How to ensure that a randomly-generated velocity vector moves the camera forward within a valid arc?
Something like this should work:
...
- 2,232
1
vote
Accepted
Fastest Simulation Of Mass Spring Systems
Time integration with implicit Euler is unconditionally stable. This means you can choose arbitrary large time steps without worrying that your solution "explodes". In contrast to explicit ...
- 1,261
1
vote
Accepted
Physically Based Shading for Diffuse surfaces
So after reading up some more research papers and the concepts of most people working in this field here and there, I've reached an answer I'm satisfied with. If someone disagrees or thinks there is a ...
- 2,518
1
vote
Rendering Equation for photons carrying flux
It'd be hell a lot easier if this were on graphicsexchange, since I can't use latex here but anyways.
In the first pass of Photon Mapping you don't need to use the Flux form of rendering equation. ...
- 2,518
1
vote
Accepted
How to rotate a shape in another 3D software so that the rotation matches with the rotation in Blender?
I just had to make the following changes to [manually] change the coordinate system of FleX to the one that Blender uses:
...
- 241
1
vote
Why are BRDF and the lighting uncorrelated?
When rendering an image you are trying to find the outgoing light from a point into the camera $L(x \rightarrow \Theta$).
To do this you solve "The rendering equation", which means you integrate the ...
- 588
1
vote
Accepted
Spring damping in Energy Function
The damping force you mentioned $f=-k \frac{\dot{l} \cdot l}{|l|} \frac{l}{|l|}$ is a special case of $f=-k \dot{C} \frac{\partial C}{\partial \mathbf{x}}$.
Let
$$
\begin{align}
C(\mathbf{x}) &= \...
- 655
1
vote
Accepted
Hooke's Law vector form
If we sidestep your typo (the last term has one absolute too much), both formulations are correct. They just express different things. The $k$ in Hooke's law is for a particular spring. $k_s$ is the ...
- 8,457
1
vote
Accepted
Beginner CG Research Project
If you are going for physics. You can do physically based rendering. Physically Based Rendering(PBR for short) is a filed of computer graphics where we take consider of physics(energy conservation, ...
- 661
Only top scored, non community-wiki answers of a minimum length are eligible