Unanswered Questions
483 questions with no upvoted or accepted answers
14
votes
0answers
520 views
What exact algorithm and parameters reproduce L-system plant growth figure in Algorithmic Beauty of Plants
I am interested in duplicating a figure (shown below, ch 1 fig 1.21) in the book Algorithmic Beauty of Plants. The book is available here
http://algorithmicbotany.org/papers/#abop
This image appears ...
11
votes
0answers
298 views
Why does increasing simplex noise dimension wash it out?
I just tried using this approach to create a tiling 2d simplex noise function with Gustavson's java implementation. The result tiled, but the texture seemed muddy / washed out.
I decided to compare ...
11
votes
0answers
399 views
Problem with definition of BSDF and radiance
When I was reading theory behind physical based rendering I noticed that definition of BSDF and radiance has some problems. For example BSDF of purely specular surfaces is zero almost everywhere and ...
10
votes
0answers
373 views
Using Monte carlo on Rayleigh scattering
Update
I am editing and posting this question in a different way; this time from the point of view of Nishita paper.
Sunlight gets scattered at P and attenuated before reaching Pv. Therefore ...
10
votes
0answers
445 views
How correct is rendering in XYZ / linear RGB space?
I have a spectral power distribution (SPD, 5 nm steps) for all light sources in the scene and SPDs for the reflectance of all surfaces under any light / viewer angle in question.
I'm going to ...
9
votes
1answer
323 views
The most performant way to organize vertex data on modern GPUs
Say I have a model made up of vertices, each with position, normal, tangent, and ...
9
votes
0answers
166 views
Help with start up bias in Metropolis Light Transport
I'm trying to implement metropolis light transport based on this paper, and I have the basic thing working. I run the algorithm multiple times with different starting points, add the results for each ...
9
votes
0answers
285 views
WebGL packing/unpacking functions that can roundtrip all typical 32-bit floats
I have a WebGL circuit simulator. One of the problems it has is that, due to using quite a lot of intermediate float textures as it simulates, it doesn't work on various mobile devices. They only ...
9
votes
0answers
218 views
Choosing width of data for signed distance field texture
A signed distance field texture is a technique where you store the distance from a pixel to the surface of a shape within the color information for that pixel, allowing almost vector graphics quality ...
9
votes
0answers
127 views
How to describe the bi-directional links for the Weiler-Atherton algorithm?
My postscript interpreter currently implements the Hodgeman-Sutherland clipping algorithm but this is limited to simpler shapes and doesn't have a provision for utilizing various winding-number rules. ...
8
votes
0answers
692 views
More accurate Fresnel approximation for a RGB-based Path Tracer
I'm writing a path tracer and, for the moment, spectra related data (spectral power distributions and spectral reflectance curves) are stored as RGB tuples. In the Cook-Torrance specular BRDF I am ...
8
votes
0answers
378 views
3D mesh segmentation simple algorithm
I am developing the algorithm reported in this article:
Least square conformal mapping.
Here is presented an algorithm to flat a 3d mesh on the parametric space, but i don't understand the ...
7
votes
0answers
181 views
Supersampling HDR
I'm encountering some issues supersampling in HDR for an SDR result and was curious what the usual method for doing this is. Notice how pixelated the edge of the white sphere is.
Here's how I render ...
7
votes
0answers
994 views
Bump mapping a ray-traced sphere
I'm attempting to apply a height map to a ray-traced sphere. The height map is stored as a texture. I have the intersection point on the sphere $p$, and I compute the normal vector at that point $N = ...
7
votes
0answers
321 views
Code runs differently on different hardware
I wrote a 2D fluid-solver in OpenGL (code here) some time back.
While it runs flawlessly on my onboard Intel GPU,
the simulation very quickly "blows-up" when same code is run using nvidia card :
...
