| People spend about 90% of their time indoors,and the demand for indoor navigation and location services tends to be personalized and precise.The indoor space model is the foundation of indoor navigation and location services.The effective organization and expression of geometric,semantic,and topological data directly affects the level of navigation and location services.Therefore,for the various requirements of indoor navigation,an indoor space model with accurate geometric expression,rich semantic information,and complete description of spatial topological relationships is required.In the current research,the indoor space model oriented to indoor navigation has insufficient combination of semantics,geometry and topology.At the same time,the expression and description of the spatial topological relationship between indoor objects in buildings is incomplete.In the extraction of indoor spatial topological relations,many scholars use BIM and City GML models as the main data sources,but the data is not easy to obtain,the timeliness is poor,and the extracted indoor spatial topological relations are not comprehensive.The point cloud has gradually become a data source for indoor model construction and indoor navigation in recent years due to its fast acquisition speed,high accuracy,and the ability to reflect the real information on the surface of an object.This paper presents a data organization model for indoor navigation,which takes the indoor space topological relations of buildings as the research object,and presents a set of methods to extract the indoor space topological relations using point cloud as the data source.This study can provide model data support for indoor navigation location service,indoor emergency response and indoor scene display.The main research work and results of this paper are as follows:(1)A data organization model of architectural indoor spatial topological relations oriented to indoor navigation is proposed.The model is based on the geometric model expression of City GML,and uses the ADE application extension technology to extend the expression of semantic objects,semantic attribute information and topological relations.On the basis of summarizing the spatial objects and component objects in the building,the indoor objects that are not fully expressed in the City GML standard model are supplemented.The model designs a data organization module for the topological relationship of indoor space,and uses nodes and relationship edges to explicitly express the three basic relationships among indoor objects("space-space","space-component","component-component").As the basis of topological expression,the aggregation,connectivity,and adjacent relationships are stored in the corresponding spatial object attributes in a hierarchical manner,which improves the efficiency of spatial query.The model integrates semantic,geometric,and topological information,fully describes and expresses the spatial topological relationship between indoor objects,and can provide model data support for indoor navigation location services,indoor emergency and other fields.(2)Propose a method to extract the topological relationship of the indoor space of the building with the point cloud as the data source.The method takes the point cloud indoor space as the entry point,and decomposes it in the order of "building-floor-room-component" from top to bottom.In the room division,the idea of exploring the door in the point cloud and combining the image method is adopted,and the upper plane of the door frame of the room is selected in the point cloud data to determine the position of the door to avoid excessive segmentation.In the extraction of the indoor spatial topological relationship,the connection,adjacency and aggregation relationship between the rooms of a single floor are extracted based on the room division diagram of the floor;under the room constraint,the relationship between the aggregation relationship within the room and the wall components is extracted.The adjacent relationship between the floors;the connection relationship between the floors is obtained according to the vertical passage between the floors.Directly using indoor point clouds as the data source not only avoids the problem of model timeliness due to its faster update speed,but also the extraction results can provide data support for BIM model construction.The method fully considers the connection,neighboring,and aggregation relationships among indoor objects involved in indoor navigation and spatial query,and the extraction results can provide services for indoor navigation and spatial query.(3)Design experiments for analysis and verification.The experiment uses C++ as the main development language,and uses the indoor point cloud data of the first and second floors of Building F,College Building,Daxing Campus,Beijing University of Architecture and Architecture as experimental objects.In the experiment part,the indoor point cloud data of the first and second floors are divided into space and the spatial topological relationship is extracted,and the adjacent relationship between the result of space division and the inner wall of the room is used as a reference to construct the standard City GML indoor 3D of the first and second floors model.Based on the research results of the BISTRM model of architectural indoor spatial topological relationship,XML language is used to generate the Schema description file of the model.Finally,using the description file of the model as a reference,the spatial topological relationship extraction results are combined with the standard City GML indoor threedimensional model to construct an indoor three-dimensional model of the building with spatial topological relationship.The model not only describes the detailed indoor environment,but also accurately expresses the spatial topological relationship between indoor objects in the building,which proves the effectiveness of the data organization model and the topological relationship extraction method. |
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