We present a set of maximum entropy reconstructions of the starspot distribution on the surface of the rapidly rotating KO dwarf AB Doradus. The images were obtained from three independent data sets secured on three consecutive nights of observation at the Anglo-Australian Telescope in 1992 January. We discuss the effects of several potential types of systematic error in Doppler imaging, and methods of eliminating them. Independent reconstructions are presented in the three photo spheric lines: Ca I 643.9 nm, Fe I 666.3 nm and Ca I 671.8 nm. All the images indicate a bimodal latitude distribution of spot area coverage, with a broad low-latitude band and a circumpolar `crown'. The gross azimuthal structures in the polar crown and the low-latitude band show no evidence of longitude shifts over the duration of the observing run. On the time-scale of a single stellar rotation the star's surface layers thus appear to be in a state of nearly solid-body rotation. Key words: techniques: image processing - stars: activity - stars: atmospheres - stars: individual: AB Dor - stars: magnetic fields - stars: rotation.