In the face of complicated, diversified three-dimensional world, the existing 3D GIS data models suffer from certain issues such as data incompatibility, insufficiency in data representation and representation types, ...In the face of complicated, diversified three-dimensional world, the existing 3D GIS data models suffer from certain issues such as data incompatibility, insufficiency in data representation and representation types, among others. It is often hard to meet the requirements of multiple application purposes(users) related to GIS spatial data management and data query and analysis, especially in the case of massive spatial objects. In this study, according to the habits of human thinking and recognition, discrete expressions(such as discrete curved surface(DCS), and discrete body(DB)) were integrated and two novel representation types(including function structure and mapping structure) were put forward. A flexible and extensible ubiquitous knowledgeable data representation model(UKRM) was then constructed, in which structurally heterogeneous multiple expressions(including boundary representation(B-rep), constructive solid geometry(CSG), functional/parameter representation, etc.) were normalized. GIS's ability in representing the massive, complicated and diversified 3D world was thus greatly enhanced. In addition, data reuse was realized, and the bridge linking static GIS to dynamic GIS was built up. Primary experimental results illustrated that UKRM was overwhelmingly superior to the current data models(e.g. IFC, City GML) in describing both regular and irregular spatial objects.展开更多
For storing and modeling three-dimensional(3D)topographic objects(e.g.buildings,roads,dykes,and the terrain),tetrahedralizations have been proposed as an alternative to boundary representations.While in theory they ha...For storing and modeling three-dimensional(3D)topographic objects(e.g.buildings,roads,dykes,and the terrain),tetrahedralizations have been proposed as an alternative to boundary representations.While in theory they have several advantages,current implementations are either not space efficient or do not store topological relationships(which makes spatial analysis and updating slow,or require the use of an expensive 3D spatial index).We discuss in this paper an alternative data structure for storing tetrahedralizations in a database management system(DBMS).It is based on the idea of storing only the vertices and stars of edges;triangles and tetrahedra are represented implicitly.It has been used previously in main memory,but not in a DBMS.We describe how to modify it to obtain an efficient implementation in a DBMS,and we describe how it can be used for modeling 3D topography.As we demonstrate with different real-world examples,the structure is compacter than known alternatives,it permits us to store attributes for any primitives,and has the added benefit of being topological,which permits us to query it efficiently.The structure can be easily implemented in most DBMS(we describe our implementation in PostgreSQL),and we present some of the engineering choices we made for the implementation.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41271196)the Key Project of the 12th Five-year Plan,Chinese Academy of Sciences(Grant No.KZZD-EW-07-02-003)
文摘In the face of complicated, diversified three-dimensional world, the existing 3D GIS data models suffer from certain issues such as data incompatibility, insufficiency in data representation and representation types, among others. It is often hard to meet the requirements of multiple application purposes(users) related to GIS spatial data management and data query and analysis, especially in the case of massive spatial objects. In this study, according to the habits of human thinking and recognition, discrete expressions(such as discrete curved surface(DCS), and discrete body(DB)) were integrated and two novel representation types(including function structure and mapping structure) were put forward. A flexible and extensible ubiquitous knowledgeable data representation model(UKRM) was then constructed, in which structurally heterogeneous multiple expressions(including boundary representation(B-rep), constructive solid geometry(CSG), functional/parameter representation, etc.) were normalized. GIS's ability in representing the massive, complicated and diversified 3D world was thus greatly enhanced. In addition, data reuse was realized, and the bridge linking static GIS to dynamic GIS was built up. Primary experimental results illustrated that UKRM was overwhelmingly superior to the current data models(e.g. IFC, City GML) in describing both regular and irregular spatial objects.
基金This research is supported by the Dutch Technology Foundation STW,which is part of the Netherlands Organization for Scientific Research(NWO),and which is partly funded by the Ministry of Economic Affairs(project codes:11300 and 11185).
文摘For storing and modeling three-dimensional(3D)topographic objects(e.g.buildings,roads,dykes,and the terrain),tetrahedralizations have been proposed as an alternative to boundary representations.While in theory they have several advantages,current implementations are either not space efficient or do not store topological relationships(which makes spatial analysis and updating slow,or require the use of an expensive 3D spatial index).We discuss in this paper an alternative data structure for storing tetrahedralizations in a database management system(DBMS).It is based on the idea of storing only the vertices and stars of edges;triangles and tetrahedra are represented implicitly.It has been used previously in main memory,but not in a DBMS.We describe how to modify it to obtain an efficient implementation in a DBMS,and we describe how it can be used for modeling 3D topography.As we demonstrate with different real-world examples,the structure is compacter than known alternatives,it permits us to store attributes for any primitives,and has the added benefit of being topological,which permits us to query it efficiently.The structure can be easily implemented in most DBMS(we describe our implementation in PostgreSQL),and we present some of the engineering choices we made for the implementation.
