A New Data Model on Urban Pipeline GIS: Directed-Node Model

In this paper, the authors proposed a new data model named directed-node and gave its related definitions, types, classification, and how to create directions. Directed-node model simplified geographical network modeling from dualistic structure with edges and junctions to unitary structure just with nodes. It emphasized nodes were the core elements and not employed lines which were represented now by connections between directed-nodes. Only directed-nodes data need to be gathered and the connections between nodes can be generated automatically by pre-assigned arithmetic. Two tables were created to store respectively attribute and connections and three tables stored result paths. So it made directed-node model homogenous with database. Thereby, all maintenance and analysis on pipeline data became operation on database tables, which made full use of standard SQL. The customized trade rules also had been introduced to enable topological integrity, validity and rationality of connection between directed-nodes, which reduced errors, increase efficiency, made data processing and analysis more simple, intelligent and friendly. We argued that directed-node model should uplift pipeline GIS to a new height.