On the Concept and Integration of Geologic Time in Planetary Mapping

Abstract

Planetary image data and maps form one of the most accessible scientific products for establishing cross-communication between planetary research disciplines and the general public. In particular geologic maps comprise a wealth of thematic information and form an accessible and esthetic medium for both, laypersons as well as scientist. Geologic maps form a substantial part of the planetary map data record that is publicly available. If such maps have been designed carefully they condense 2.5 + t dimensions (coll. 4D) into a two-dimensional map domain by connecting thematic attributes with geometry and time and by allowing (a) to completely reconstruct the subsurface extent as well as attitudes of mapped units by means of geometry, and (b) to establish a sequence of time units by relating legend items with geometric reconstructions. Despite the well-considered design of such maps, their higher non-geometric dimensionality and compression to two dimensions cause severe limitations in querying mixed non-spatial and spatial relationships, e.g., time, even in digital systems. This, however, is required for geological mapping in order to establish cross-relationships across regions on a local and even planetary scale. We here present a data framework which allows storing, managing and querying 2.5D + t information used in planetary geologic mapping. The focus is put on the general abstract ontological as well as the logical relationship concept which is designed to be employed in state-of-the art geographic information systems (GIS) commonly used for planetary geologic mapping.