User interfaces to three-dimensional environments are becoming more and more popular. Today this trend is fuelled through the introduction of social communication via virtual worlds, console and computer games, as well as 3D televisions.
We present a synopsis of the relevant abilities and restrictions introduced by both input and output technologies, as well as an overview of related human capabilities and limitations, including perceptual and cognitive issues. Partially based on this, we present a set of guidelines for 3D user interfaces. These guidelines are intended for developers of interactive 3D systems, such as computer and console games, 3D modeling packages, augmented reality systems, computer aided design systems, and virtual environments. The guidelines promote techniques, such as using appropriate constraints, that have been shown to work well in these types of environments.