Installation
I did the entire assignment remotely on myth.stanford.edu. Everything went smoothly.
Experimentation
Setting the picture to 200x200 and the sample per pixel to 2, on myth it's pretty fast. Also I wrote a script
!/bin/sh
pbrt lighting.pbrt
exrtotiff lighting.exr lighting.tif
gnome-open lighting.tif
to make it even faster.
To seperate effects of the 4 light sources, I used different color for each light source.