Indoor Three-dimensional Model Data Organization For Location Based Services

With the continuous construction and development of digital cities,complex buildings represented by large commercial centers,underground parking lots,apartments,office buildings,residences,and large-scale indoor public places have increased rapidly in cities.Meanwhile,people have the demand for LBS gradually shifts from outdoor to indoor,and the indoor space model is the basis of indoor location services.A reasonable and effective expression and organization of indoor three-dimensional model data can effectively improve the capabilities of indoor LBS.The existing indoor three-dimensional model focuses on the geometrical expression of the indoor space and is oriented towards the application of visualization.It lacks the effective expression of the model's own rich semantics and spatial associations,and it is difficult to satisfy the needs of indoor space location services such as thematic queries,analysis,and path planning.Aiming at the rich semantics and spatial geometrical characteristics of 3D models of complex building interiors,we need to study a method of expressing and organizing indoor 3D models oriented to indoor LBS.The main research content of this article includes:(1)An indoor space location model based on the IndoorGML standard is proposed.From the perspective of application requirements of indoor location services that meet human cognition,through the analysis of the geometric,topological and semantic features of large-scale and complex buildings,and aiming at the inadequacies of the representation of the LBS in IndoorGML,an indoor space location model(ISLM)containing the geometry,topology,and semantic location information is constructed.(2)An indoor level of detail model for LBS is studied.By analyzing the service application requirements of different locations of 3D models,and referring to the representation of CityGML multiple level of detail model in the urban space domain,the ISLM is divided into multiple levels of detail,and the indoor LOD of BuildingBlock,BuildingFrame,Storey,and Room are proposed.Based on GML and IndoorGML specifications and creation rules,we designed and formulated an XML schema for indoor LOD model.(3)A method for organizing indoor 3D model data that takes into account the semantic and topology is proposed.Based on the ISLM and the its expression of LOD,the spatial elements of the indoor 3D model were divided according to semantic spaces,and based on the analysis of the relationship among the component objects and space objects that were divided,an indoor 3D model data organization method that takes into account the semantic and topology is proposed to provide support for spatial LBS such as 3D indoor location query,analysis,and path planning.(4)This paper experimented and analysiz the indoor 3D model expression and organization method proposed in this paper.Taking the innovation center of the University of Electronic Science and Technology as the experimental object,based on the indoor space location model proposed in this paper and its expression of LOD,the application of indoor path planning in LBS validates the effectiveness of the proposed method for the representation and organization of indoor 3D models.