[Radiance-general] radiance graph

[Jelle Feringa / EZCT Architecture & Design Research]

Hi,

Currently I'm trying to construct a light-graph of a given scene by
raytracing Radiance samples using rtrace, and dumping these to a polyline
instead of pixels. I think such a graph could give a lot of insight apart
from an image as well. Also I like the idea of being able to construct
geometry instead of generating yet another pixel. I already have sooo many
of these. 

Thing is that my experiment has only been semi successful, and I'd like to
hear what you think of it: I've made it available on my server:
www.ezct.net/radiance

The technique I used is simple, I have been using the following commandline:

ximage trace.pic | rtrace -ab 1 -ds 0.2 -dr 6  -dt 1 -otodp -h -x 1 -i
ok.oct  > raytrace_sample.dmp

The coordinates in raytrace_sample.dmp are converted to .dxf geometry.
To give you some insight, I've merged it with the original scene:
radiance_graph_01_in_context.dxf

The problem so far is that 'graph' implies clarity, and as you'll see, my
experiments so far are rather noisy. Getting lots of rays isn't the point,
getting the ones that matter is another! The other thing is that I do not
know how I could generate such a point dump from a whole image instead of
sampling a single pixel, as I'm doing now. I've done some experiments
sampling many points, but that's not the way to do it. How could I have
rtrace trace all pixels in a given picture?

To make the graph more clear, it would be interesting to color them for
instance accordingly to how often a ray bounced. What would be a good way
for scripting rtrace such that I'll be able to do so?

Another thing would be that the graph would be most coherent when a ray is
traced from camera all the way to the source. Would my best option be to
render with just a sun and to forget about the sky? I've tried a couple of
option but it seems difficult to have many rays reach a light source.

Love to hear what you think of it.

Cheers, 

Jelle.