Drawing the Gaps: Graphical Methods for Representing Geospatial and Temporal Uncertainty with Cultural Artifacts

Abstract

Modern visualization tools can present geographic information system (GIS) data as a 3D rendering, facilitating a user's understanding of the geospatial relationships between terrain and cultural features. While this capability has been present for some time in professional GIS systems such as Arcinfo, it is now also available in commodity programs such as Google Earth. As is the case with most large knowledge bases, source data in GIS systems is often incomplete, contradictory, or otherwise uncertain. This paper describes an approach to indicating uncertainty in the location and lifespan of cultural features in GIS visualizations. Such indications of uncertainty are important even when source data comes from ostensibly reliable sources. They become nearly essential with communitysupplied source data such as Google Earth's 3D Warehouse. Representing uncertain data in the same context with accurate data requires contrasting between the two as well as keeping the representation as perceptually facile as possible. We start by organizing uncertainty into a small set of broad categories that are useful to distinguish between in many GIS visualization applications. We then argue that the 3D display in GIS system should use specific graphical styles to depict different types of data uncertainty.