Non-photorealistic Rendering on Mobile Devices and its Usability Concerns

The increasing amount of geographic data in urban environments and the technological advances in the domain of mobile devices have stimulated cartographers to give a try with the 3D visualisation of urban information on small mobile displays. The paper is focused on one of the fundamental research questions: How can we design a mobile 3D virtual urban environment that allows its users a cognitive adequate information processing? The prevailing photorealistic visualisation techniques reveal some drawbacks with regard to mobile usage context. We believe that the non-photorealistic rendering (NPR) approach with its capability to unite the advantages of photorealistic presentation style and abstract 2D maps can better satisfy the design constraints for mobile applications. Starting from an outline of the development trends of virtual urban environments, we give an overview of 3D NPR techniques along with their potential of 3D information communication to mobile users. Based on a general analysis of usability issues, we propose “cognitive adequacy” as the usability measure for NPR approach. A set of applicable graphic variables and design options are presented as our first results. In the further stages of our work, two extensive virtual urban environments with NPR approach will be implemented in accordance with the OGC format CityGML and undergo usability tests.