2. Lightweight of spatial surveying and mapping data The essence of BIM design based on spatial mapping is the integration of multi-source data in BIM design software. There are many types of spatial surveying data, various storage formats and huge amount of data. If directly integrated into BIM design software, huge amount of data will reduce the efficiency of data management and transmission, which is not convenient for designers to manage and use. Therefore, the lightweight of spatial mapping data is an urgent problem to be solved. High density point cloud data can be obtained in various ways, which is the basis of grid construction, while scene model adds corresponding texture information on the basis of grid. Therefore, this paper chooses high density point cloud data and scene model data as the research object of lightweight processing.