The Macula is "a project dealing with the relationship between image, sound and audience." Their goal is to satisfy "audiovisual nihilism" (according to Google Translate). Which could mean, I suppose, to maximize the meaning and purpose between audiovisual and audience interaction.
The Prague Astronomical Clock is "composed of three main components: the astronomical dial, representing the position of the Sun and Moon in the sky and displaying various astronomical details; "The Walk of the Apostles", a clockwork hourly show of figures of the Apostles and other moving sculptures; and a calendar dial with medallions representing the months." The clocks interwoven dials represent:
Video projector mapping works like this: "A number of computer controlled video projector effects are used to project an image on to a desired surface. The projection surface is then mapped into the computer. We can then define various points from the surface and store these into the computer, giving us a selection of ‘maps’. These maps can then be layered with video content, still images, live video feeds, logos, branding etc, to create an ‘interactive’ surface."
Video mapping is a relatively new artform derived from VJing, the realtime manipulation of visual elements (just like DJing is like manipulation of audio elements). Where traditional VJing was stuck in 2-dimensions, video mapping aims to maximize all the dimensions within a space.