37
votes
Accepted
Why does monte carlo ray tracing perform better than distributed ray tracing?
The term "distributed ray tracing" was originally coined by Robert Cook in this 1984 paper. His observation was that in order to perform anti-aliasing in a ray-tracer, the renderer needs to perform ...
- 2,595
20
votes
Accepted
Why is it twice as expensive to make a noise function that can be tiled?
It's unfortunate that people commonly recommend this. Blending between two (or four, etc.) translated copies of a noise function in that way is a pretty bad idea. Not only is it expensive, it doesn't ...
- 24.7k
16
votes
How is anisotropic filtering typically implemented in modern GPUs?
The texture filtering hardware takes several samples of the various mipmap levels (the maximum amount of samples is indicated by the anisotropic filtering level, though the exact amount of samples ...
- 1,130
16
votes
Accepted
Visualizing the Lane-Riesenfeld Algorithm
The Lane-Riesenfeld algorithm subdivides the control polygon of a B-spline to create a new control polygon with the same limit spline. It's made up of two steps: first, duplicating all of the control ...
- 881
15
votes
Algorithm to find the center of a Bezier curve
Bézier curves are mathematical entities and have no clearly defined center. One can in fact define many different things as the center of the Bézier curve. I have tried to depict some of the possible ...
- 8,367
13
votes
Accepted
Shading: Phong vs Gouraud vs Flat
Flat shading is the simplest shading model. Each rendered polygon has a single normal vector; shading for the entire polygon is constant across the surface of the polygon. With a small polygon count,...
- 1,592
13
votes
Changing image so it would look like through colorful glasses
(XYZ) can be the RGB colour you want to tint your scene by. For the above scene it can be a red colour (1.0, 0.0, 0.0) or something similar with a strong red component.
Bear in mind that since you ...
11
votes
Accepted
Detect in-focus regions of an image
it is quite easy to measure the local max frequency in an image (at least as a low resolution mask, with some regularization).
Several papers of the MIT graphics group have been around detecting and ...
- 1,266
11
votes
How can I concentrate points in areas of higher curvature?
The idea I would try to apply would be the following: I make the example for the curve, but it should be straightforward for the application for the surface.
Let's say we have a curve $\gamma$ ...
- 526
11
votes
Accepted
How to modify Perlin (not simplex) noise to create continental like terrain generation
Perlin noise is just a base block, not very interesting by itself. You don't need to modify it, but to combine and filter it in interesting ways. Look at how to make fractal Brownian motion (fBm) with ...
- 4,380
10
votes
Accepted
Seamless Textures
For these types of algorithms, you usually have to rely on multiple forms of texture synthesis. That doesn't mean you have to generate the whole texture from scratch. For example, you could regenerate ...
- 1,353
9
votes
Accepted
Modelling Young's double slit experiment
It is in fact possible to augment a ray tracer to make it capable of simulating wave effects. The paper Rendering Wave Effects with Augmented Light Field
describes one way to do it. In summary, they ...
- 2,595
9
votes
Is there some kind of Bresenham algorithm or equivalent for scanline rendering a rotated ellipse?
The classic book Computer Graphics: Principles and Practice (second edition) by Foley, van Dam, et al. describes such an algorithm in section 19.2.
The explanation in the book seems to come from an ...
- 724
9
votes
How is anisotropic filtering typically implemented in modern GPUs?
The API requirements can be found in any of the specs or extensions. Here is one: https://www.opengl.org/registry/specs/EXT/texture_filter_anisotropic.txt
All GPU vendors likely deviate from the spec ...
- 2,194
9
votes
Accepted
What algorithm is used in the animation of the uTorrent 's "About window"?
As you discovered and mentioned in your self-answer, the pattern in the background appears to be a sum of sinusoidal gradients.
However, the example linked to in your answer is more complicated than ...
9
votes
Why are oct trees so much more common than hash tables?
Lots of things here.
"When reading papers". What papers? If the topic of the paper is about something other than the spatial partitioning structure, it could be fair to use whatever knowing that the ...
- 91
8
votes
Accepted
Understanding Jump Flooding Algorithm (JFA) for Voronoi Diagrams
I think that there is a bit of confusion in terminology. My understanding is that only the initially colored points, before step 1, are called seeds.
Maybe this helps clarify the algorithm as well. ...
- 306
8
votes
Accepted
How do people come up with subdivision schemes?
The subdivision schemes are not arbitrary. Catmull-Clark, arguably the most used subdivision scheme, generalizes bicubic B-splines to meshes of arbitrary topology.
Most, other subdivision schemes ...
- 1,089
7
votes
Accepted
scan line algorithm is too slow?
One red flag is the use of new several times within the loop. Memory allocation doesn't belong in a rasterizer! :) Certainly you should not need to allocate a ...
- 24.7k
7
votes
Algorithms to Remove High Frequency Noise from Path Tracing
There are, and I am looking forward to seeing the specifics of other answers, but one way to deal with this is to not have the noise (or as much noise) in the source data to begin with.
The noise is ...
- 7,721
7
votes
Accepted
How does the Painter's Algorithm handle transparency?
The common way to render transparent polygons in a rasterizer is by use of Alpha Blending, which basically combines the colour of the supposedly transparent pixel with the colour of the background at ...
- 1,626
7
votes
Accepted
What algorithm is used in this animation from Tatami Galaxy?
It looks like a voronoi diagram with a non-Euclidean distance metric. Probably not Manhattan L1 but something close related, but maybe Mahalanobis with some kind of restriction on seed point ...
- 301
6
votes
Perturbed image texture implementation from renderman language
As you've surmised, the transform() function transforms points from one co-ordinate space to another. (There are also ...
- 6,680
6
votes
Accepted
Optimal memory access when using lookup tables on GPU?
The best place to put a look up table for a GPU compute shader depends on the size of the lookup table, and the frequency/coherency of access. In your case (you mentioned 4kb), shared local memory ...
- 593
6
votes
Strategy for connecting 2 points without intersecting previously drawn segments of curves
The general problem is called graph drawing and is not an easy problem.
The graphs that can be drawn on the plane without crossings are called planar, but not all graphs are planar: the typical graphs ...
- 724
6
votes
How to implement a realtime 2D light renderer with fog/colored light on the GPU?
If your wall geometry is vector graphics you can simply extrude the segment away from the light position. This means 2 triangles per draw call, all the extrusion offsets can can be handled in the ...
- 8,367
6
votes
Accepted
Changing image so it would look like through colorful glasses
Extending Kostas Anagnostou's answer, a commonly used formula for desaturation is
float value = 0.3 * InputR + 0.59 * InputG + 0.11 * InputB;
This accomodates ...
- 2,293
6
votes
Why does monte carlo ray tracing perform better than distributed ray tracing?
In Distributed ray tracing, You stochastically sample many rays in directions which may or may not be preferred by the BRDF. Whereas, in Monte Carlo ray tracing or simply path tracing, you sample only ...
- 181
6
votes
Accepted
How should I fill a shape consisting of Bezier curves and straight lines?
If you are in a hurry to get your renderer working and you already have the filled polygonal routine functioning correctly, can I suggest an alternative, possibly easier approach? Though I'm not ...
- 4,151
Only top scored, non community-wiki answers of a minimum length are eligible