The Research Of Entity Oriented 3D Spatial Data Model And Its Application

This thesis aims to study the construction and application of spatial entity data model in 3D GIS.The 3D spatial data model is the foundation of and the key to the development and application of 3DGIS.In the fields of 3D spatial data model,it is critical to illustrate geospatial environment accurately and completely.Currently,most of data models mainly focus on investigating geometric features of spatial entities.Since spatial attributes and spatial relations are indispensable part of 3D spatial analyses and applications,it is necessary to enhance the expression of entities' attributes and relations.Since spatial attributes and spatial relations are indispensable part of 3D spatial analyses and applications,it is necessary to enhance the expression of entities' attributes and relations.The entity oriented 3D model is an important way of expressing 3D spatial data model.It is capable of recording logical relationships between entities(e.g.spatial and semantic relations)and demonstrating geometric features of spatial entities.This research designed an entity oriented 3D spatial data model on the basis of existing data models,proposed a method of organizing data models derived from R-tree space index,constructed database of,and discussed quick scheduling mechanisms of entity models.In the end,the newly designed entity oriented 3D spatial data model was applied to urban space with high density to derive establishment and architecture of urban spatial entity models for designing the database of urban entity 3D models efficiently.The main contents of the research are listed below.(1)Investigated and summarized the advantages and disadvantages of existing 3D spatial data models.It was found that current data models intend to the expression of geometric features of geographical spatial entities,but they are insufficient in illustrating attributes and relationships of entities.On the other hand,entity oriented data models are capable of storing and characterizing attributes and relationships of entities while expressing geometric features.To sum up,it is practical and convenient to take entity objects as the core and to encapsulate all the features of entities in objects for facilitating spatial analyses and applications.(2)Research reviews on theories and technologies of the construction of 3D entity models,the techniques of entity oriented 3D modeling,and the visualization methods of 3D entity models.These theories and techniques are important foundation of building 3D entity models.(3)Designed an entity oriented 3D spatial data model,and defined entity models conceptually in a detailed way.The organizational structure of entity models were designed based on the entity oriented 3D spatial data model.Entity models contained four parts: spatial attributes,non-spatial attributes,spatial relationships and spatial methods.In addition,the thesis investigated the organization and management of entity models after the data structure of entity models was derived,including LOD model,spatial R-tree index,and the construction of spatial entity model database.In the end,quick scheduling mechanism of 3D entity models was studied to schedule entity models effectively.(4)Applied the 3D entity model to complex urban space with high density and investigated the data characteristics of urban space geographic entities.After that,the construction and organizational methods of urban entity models were investigated by hierarchical and partitional methods.The thesis also constructed database of 3D urban spatial models and designed and applied the visualization of 3D urban spatial entity model.The realization of the system is significant and reasonable to the application of 3D models and the application of 3D GIS in urban space.