In some implementations, a method performed by data processing apparatuses includes receiving map data that identifies a layout of physical objects within a physical area, identifying contiguous groups of the physical objects as composite objects, selecting bounding algorithms to use for generating graphical shapes for the composite objects, generating graphical shapes by applying the selected bounding algorithms to the composite objects, and testing the graphical shapes against one or more criteria. For candidate graphical shapes that fail a test, a new bounding algorithm can be selected and the generating and the testing can be repeated using the new bounding algorithm. A simplified graphical map can be output that represents the physical objects within the physical area using the graphical shapes.