Unanswered Questions
833 questions with no upvoted or accepted answers
15
votes
0answers
716 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 ...
13
votes
0answers
552 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 ...
12
votes
0answers
933 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
722 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 ...
10
votes
0answers
294 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
242 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
449 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
151 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
449 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
223 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
2k 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
574 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
157 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
486 views
How to account for self intersection with large ray tracing scenes?
I'm working on a hybrid real time ray tracing project and trying to tackle the problem of self-intersection with larger scenes due to loss of float accuracy. The logic I'm trying to use is based on ...
