[Radiance-general] PMAP simulation

[Jan Wienold]

Hi Anthony,

first of all, I think it's a good idea to read the documentation (which 
is part of the distribution) to have an idea what pmap does. Within that 
documentation all parameters are explained.

The quick instruction is:

0. You can use the standard radiance description (except user defined 
BRDFs). ->rad and oct

1. To distribute photon and store them in files (global and caustic 
photons separately)
e.g.
~/bin/radiance/pmap/mkpmap  -apg f81_z.gp 700000 -apc f81_z.cp 700000 
test.oct
700000 is the number of the photos emitted, gp : global photons, cp 
caustic photons

2. Count the photons, make a density estimate  and generate a picture 
with the modified rpict:

~/bin/radiance/pmap/rpict -apg f81_z.gp 500 -apc f81_z.cp 500  -ab 1 -x 
1200 -y 1200 -vf test.vf -o test.pic  test.oct

Similar to the existing rpict, with additional options to read in the 
photon files. You can use most of the rpict options of the 
standard-rpict. Of course, the ambient options don't make really sense 
since the ambient calculation is replaced by the forward raytracer.
In many cases, the use of the photon port mechanism is extremely useful. 
With photon ports you can define materials, through which the light 
enters the scene. A typical example is an office scene, which is lit by 
the sky. Using this, you can avoid huge effort, since the photons are 
distributed mostly in "relevant" directions. In your case it could make 
sense to define the entering cross section as "photon port". You can use 
e.g. glass material with refraction index 1 (==air!!) without disturbing 
the simulation.

Good luck!

Jan


Anthony J. Farrell wrote:

>Hi Folks,
>
>I have successfully modelled a 'lightpipe' on the Desktop radiance software
>2.0 but the results are pretty dull since it is just a backward ray tracer.
>
>Can anyone tell me how I may model this on the photon mapping version. I
>have successfully installed pmap version onto my linux. Do I simply copy all
>the windows generated files (*.rad; *.oct; *.rif; etc.) to linux environment
>and run the pmap software...what is the run command line if I want to simply
>revisual the exact same illuminance simulation that I had done with the
>Desktop version?
>
>Much appreciate any contributions.
>
>Thanks.
>
>Anthony
>
>
>  
>