A technical challenge : Other tools

On the computer, they use a tool called “mapping video” that allows image projections on a volume in 2D or 3D (it depends on what you want). The image is created on the computer and then, thanks to the laser recording, it is thrown on the monument.

Others, more traditional may be used, for example “gobos”, a word created from the English expression “Goes Before Optics”. It consists in cutting with laser a design on a metallic plate. This one will be placed on a spotlight guided by a technician.
The following video is an extract from the "son et lumiere" in Laon, in 2013 : we can easily see that there is a "gobo" in front of the spotlight, the design is a gargoyle, moving on the cathedral.

Mapping video may be used in combination with videos: Doing that will allow in the show elements form the real life (men, animals etc…), changed, modified before on computer and included in the show.

Once they did the work in the workshop and on the computer, spotlights must be placed in front of the monument and sometimes directly on it (to increase the effects). To do that they need to think about the length and width of the place in front of the monument in order to put the spotlight on the right position.

As an example, floodlighting is a show during about 20 or 30 minutes, thrown once or twice a night and two days a week. But, for only a few minutes, the work is enormous.