There are two ways of using show laser light systems: Aerial or beam show applications and graphics/surface projections. At aerial or beam shows, the spectators face the laser projector or at least spectate the laser beams from the side. The laser beams do not necessarily end on a certain surface.
Graphics projections use a surface to visualize graphics, texts etc. that are drawn by the laser. It is always necessary to have a surface where the graphics, texts, etc. are visualized on. As laser light is never ending (only getting dimmed), there is no way to do any projection without having a proper surface to project on. However, it is possible to use special projection surfaces that are not solid or have other features that help in creating 3D-like laser show projections.