A Usability Evaluation of Web Map Zoom and Pan Functions

Due to limitations on screen size and resolution, the usability of web maps relies heavily on their interface design. The main goal of this research is to find better interface designs for web maps and to facilitate their usage by the public. The research consists of two stages of investigation: (a) a survey on the operation interfaces of popular web maps; and (b) a usability evaluation of simulated interfaces by measuring task performance and conducting subjective evaluations. Since the most common operation functions of web maps are zoom and pan, these two functions were selected as the main factors to be tested by simulations. The zoom function consists of two modes: original-center zoom and re-center zoom; the pan function also consists of two modes: grouped pan buttons and distributed pan buttons. The results show that: (a) for zoom operations, an original center zoom design is more efficient than a re-center zoom design; (b) an original-center zoom design is preferred to a re-center zoom design in matching with the meaning of the zoom icons; and (c) a re-center zoom design is preferred to an original-center zoom design in the compatibility of movement directions between the map and user's mental cognition.