Understanding a natural scene on the basis of external sensors is a task yet to be solved by computer algorithms. Solving it for non-microworlds requires an appropriate formalism for representing and reasoning with sensor data and domain knowledge. This contribution investigates the suitability of the family of Description Logics (DL) for this task. DL are an offspring of First Order Logic, inheriting its well-defined, declarative semantics while offering improved computational tractability and object-oriented knowledge engineering. The first part of this contribution elaborates on...