Research On Automatic Generation Of 3D Indoor Map Based On Building Information Modeling

As the rapid development of smart city and digital construction industry,indoor maps have lay the foundation for most of the indoor location-based services,such as urban smart service,unmanned driving,fire rescue and evacuation,intelligent storage.Indoor maps also play a crucial roles in intelligent operation for robots and unmanned aerial vehicles.BIM is an important technology in the digitalization of the construction industry.The BIM model contains building data at various stages in the life-cycle of a building,and it is a high-quality data for the automated extraction of indoor maps.A complete 3D indoor map consists of the floor-level indoor maps and the cross-floor indoor paths.Current floor-level indoor maps are mainly either grid-based maps or topological maps,and the cross-floor path generation schemes are not adaptive to building elements with irregular three-dimensional shapes.To address the issues that adopting grid-based map or topological map separately during the floor-level indoor map construction cannot provide accurate and efficient indoor location-based services,and current cross-floor path generation schemes are not adaptive to building elements with irregular 3D shapes,this paper proposes a novel automatic generation scheme of the 3D indoor map using BIM data.The main research work is as follows:(1)Propose an automatic generation solution for the floor-level indoor map that integrates grid features and topological features from BIM data.By studying the existing indoor map extraction methods,this paper finds that most of the current floor-level indoor map extraction methods use either grid-based map or topological map,which lead to accuracy and efficiency problems in the application of floor-level indoor maps.To address this issue,this paper proposes an automatic generation solution for the floor-level indoor map that integrates grid features and topological features.Firstly,the floor-level grid-based map is generated using the BIM data by extracting and mapping geometric and semantic data into planar grids;Secondly,the grid thinning algorithm is used to thin the floor-level grid-based map,and the topological map is built based on the thinned floor-level grid-based map;Finally,the grid-based map and the topological map are linked and stored to form a hybrid floor-level indoor map.Because the topological map in the floor-level hybrid indoor map is generated from the grid-based map directly,there is an inherent connection between the grid-based map and the topological map,which ensures that the hybrid floor-level indoor map has both grid and topological features.During the experiment,the proposed method is applied to construct a complete floor-level indoor map in three different types of single-floor BIM models,and path planning experiments are conducted in the generated floor-level indoor map.The experimental results show that the floor-level hybrid indoor map constructed using the proposed solution integrates the advantages of grid-based map and topological map,and combines the accuracy of the grid-based map and the efficiency of topological map in the path planning applications(2)Propose an automatic construction method for cross-floor indoor paths that is adaptive to building elements with any geometric shape.Most existing cross-floor indoor path extraction methods can only construct complete and reasonable cross-floor paths from building elements with regular geometric shapes.A few study has studied the path extraction from irregular cross-floor building elements,but rely on a lot of manual work.To address the problem that the current cross-floor indoor path construction method is not universally applicable,this paper proposes an automatic cross-floor indoor path generation method for building elements with arbitrary geometry shape,and gives the corresponding algorithm.The algorithm first projects the 3D cross-floor building elements into a 2D plane(X-Z plane).Then a boundary extraction algorithm is investigated to extract the boundary from the X-Z projection image of the cross-floor building elements.Further,a X-Z topological path is generated from the extracted boundary image.Finally,the generated X-Z topological path is interoperated with the BIM components to generate a complete and reasonable cross-floor topological path.In order to verify the effectiveness of the proposed cross-floor indoor path construction method initially,eight types of typical cross-floor building elements are selected for verification experiments in this paper.The experimental results show that the proposed cross-floor indoor path construction method can automatically construct complete and reasonable cross-floor paths from cross-floor members with any geometric shape.(3)Method realization and actual case analysis of the proposed BIM-oriented 3D indoor map automatic construction algorithm.Based on the research of the automatic construction solution of 3D indoor map from BIM model,this paper designs and develops the BIM-based3 D indoor map automatic generation system based on B/S architecture,and elaborates the framework and function design in detail.This system takes the IFC format file of the BIM model as the data source,analyzes and transforms the BIM data,supports the automatic construction of 3D indoor road networks,and then,combines Web GL-oriented 3D graphics engine technology to realize BIM visualization of 3D indoor map.On this basis,this paper chooses a research building in Beijing as the experimental building and adopts the proposed3 D indoor map automatic construction method.Through the process of BIM modeling,BIM data upload and analysis,3D indoor map extraction and visualization,the 3D indoor map automatic construction and map visualization in the experimental building BIM model are realized.This paper integrates grid features and topological features in the process of generating floor-level indoor maps,which greatly improves the accuracy and efficiency of indoor map in the application of location-based services,and proposes a cross-floor path construction method for building elements with any shape to improve the applicability of indoor map generation methods for different shaped cross-floor building elements.This paper is significant to improve the automation level of 3D indoor map generation process,and provide technical support for the intelligent development of 3D indoor map in the fields of city intelligent services,robotics and indoor pathfinding.