Theory And Technology On Geospatial Data Symbolization

After the building of series scale geospatial databases having finished, using geospatial data into map production has become one of the main tasks in the field of digital mapping. But there existing partial incompatibilities between geospatial data and map data, there are also many special cases, and it still couldn?t automatically generate map data through geospatial data symbolization. Based on the reference and analysis of present researches, relevant literatures and information on geospatial data symbolization, the dissertation researched the theory and technology on geospatial data symbolization, mainly including the following contents:(1)The dissertation discusses the main reasons why it is difficult to transform geospatial data to map data, analyzes and summarizes the present researches in several aspects of geospatial data symbolization such as realization mode, the data model, mapping rules, mapping template and so on. It is expounded that how to carry out theory and technology research on geospatial data symbolization from the aspects of research target, content and program.(2)The dissertation analyzes the difference between the geospatial data and map data and their relationship with the map symbols, discusses the process of geospatial data symbolization, designs the algebraic structure of geographic features, map features and map symbols, and establishes a conceptual model of the conversion from geospatial data to map data, and from a algebra point of view the present dissertation announce geospatial data symbolization mechanism of geospatial data.(3) Directed at the map data display deficiencies of the existing map data model, a new feature association-oriented map data model is designed which could express the relationship between geospatial data and map data in the feature level, this solves the contradiction between the map feature universalize expression and the specified expression. This dissertation improves the traditional map symbol model, including improving the line symbol model at the point symbol configuration and area symbol model at the type of filled point symbol. This dissertation combines the annotations and graphics together, and puts forward a combined annotation model. The expressiveness of map symbol is enhanced.(4)According to the characteristics of cartographic knowledge and experience, this dissertation applies production representation into mapping rule formal expression, and sets up a single feature characteristics oriented mapping rule representation, as well as a analytical and operation mechanism, this model could achieve mapping rule representation that oriented feature geometry and attributes characteristics. Based on the visual space topology model, a method of constructing visual space topological relationship between symbolized features is proposed. Combining with Euclidean spatial topological relations, this dissertation expands production structure and puts forward a spatial topological relationship oriented mapping rule representation that realizes the formal expression of rules of graphics collision processing.(5)Based on analyzing the characteristics and deficiencies of the existing cartographic template and according to the whole process of geospatial data symbolization, a classification is made of mapping rules, and the symbolization process decomposes into different kinds of mapping rules, which helping to design the structure of mapping templates throughout all aspects of symbolization. Through recording the user?s mapping operations, this dissertation composes the mapping rules of all aspects of symbolization into rule set with different functions and constructs mapping templates.(6)Geospatial data symbolization tests are carried out. A map symbol library based on the map symbol model is constructed which has already been designed. At the same time, rules of symbolization control, graphics collision processing, special graphic effects processing and map decoration are constructed. Recording all kinds of rules in the type of mapping template achieves the rule and template based spatial data symbolization technology.