The 2D installation shows the relationship between a surface geometry and an outer view perspective. It's a projection of three basic surfaces: the sphere, the 2-torus (planar) and the bi-torus with two holes (hyperbolic).

The visitor chooses between one of them to carry out the interaction. In the installation, a particle is drawn simultaneously in the chosen surface from the observer's viewpoint. In an interactive table, the visitor can move a control. If the control position is shifted off center, the particle moves in this 'direction' on the surface.

As a result, the program draws a geodesic curve segment. Thus, it's possible to draw curves on the chosen surface. After a time, the first part of the curve disappears, as if produced by a trail of a particle with low persistence.