Unanswered Questions
794 questions with no upvoted or accepted answers
14
votes
0answers
686 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 ...
12
votes
0answers
728 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 ...
12
votes
0answers
529 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 ...
11
votes
0answers
690 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
0answers
230 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
416 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
283 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
148 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
2k views
Diffuse BRDF component of the Disney BRDF
In the SIGGRAPH course:
BURLEY B.: Physically Based Shading at Disney, SIGGRAPH 2012 Course: Practical Physically Based Shading in Film and Game Production, 2012.
it is mentioned that some BRDF ...
8
votes
0answers
436 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
1k 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
536 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 :
...
6
votes
0answers
149 views
Noise shaping for dithering with gamma?
The context of this question is correct dithering of color with gamma correction. In dithering we add (shaped) noise $n$ to a signal $s \in [0, 1]$ based on a random variable $r \in [0, 1]$
$$s' = s +...
6
votes
0answers
216 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 ...
6
votes
0answers
398 views
Avoiding Mach band effect when using multiple lights
I wrote a simple Phong shader with two directional lights for a project, and noticed an unpleasant artifact in the lighting. Where both lights are illuminating the same region, dark bands appear at ...
