The Fiat Lux installation consists of two linked spaces, one for performance and one for projection.

Between these two spaces are a video camera capturing the performance, a computer running custom-written software and a projector which displays the output.

Performers draw in the space using purpose-built light pens and the program (written in Processing, an open-source language developed at MIT Media Labs) evaluates the amount of brightness in the live video-stream and outputs both the raw stream and a special layer where light above a certain brightness threshold is retained.

Thus both the continuous movement of the performers and their resulting (static) drawing are recombined and both participants and viewers can see the result of their actions in real time in the projected video.

It is also possible for still images to be captured from the projected output without breaking the flow of the performance.