GIS data model is the basis of GIS data expression, organization, collection, analysis and transmission, and it is always the frontier and hotspot of GIS research.However, the existing GIS data model focuses on the expression of space or geometry, and the expression of time often adopts the discrete way, which leads to the imperfect expression of space, weak expression of time, insufficient expression of semantic and physical attribute and lack of expression of space-time relation.As an algebraic method to describe geometric problems, geometric algebra has the characteristics of unification of geometry and algebra, unification of time and space, multidimensional unification and unification of space-time expression and computation, and it is an effective mathematic tool to help GIS data model break through the above obstacles. Read More