Research On Key Technologies Of Visual Variable Analysis Of Urban Three-dimensional Models Based On Virtual Reality

With the improvement of the technology level of urban informatization,the concept of smart city construction emerges as the times require.Therefore,it is necessary to establish and improve the urban digital infrastructure,and as an important part of the digital infrastructure,the three-dimensional model of the city has a wide range of applications.Digital city is based on three-dimensional model of the city,building the upper application,displaying the data in the urban area.Thus,the visualization of three-dimensional model of the city is not only to complete the actual display of the model itself,but also to adopt special rendering methods according to the application requirements,shielding unnecessary details,highlighting key information,and realizing non-simulation visualization.In order to realize non-simulation visualization,the analysis of visual variables is indispensable.Visual variables,as the theoretical basis of symbolic design of twodimensional plane map,play a very important role in plane map symbols.However,because the three-dimensional model has higher elevation information,the visual variables in the two-dimensional plane map symbols cannot be fully applied to the three-dimensional model in GIS.Therefore,the study of the three-dimensional model visual variables plays a very important role and significance in the non-simulation visualization of urban models.Based on the traditional two-dimensional map symbols and combined with the existing three-dimensional model visual variable theory,the visual variables such as color,size,transparency,illumination and spatial posture are selected.An experimental platform is built with virtual reality and eye tracking technology.The selected visual variables are cross-validated and analyzed according to the results of the analysis through user cognitive experiments.A method of automatic mapping of visual variables in three-dimensional model is constructed by combining process determination method.The main research work of this subject is as follows:1.Based on the key technologies of virtual reality and eye tracking,the methods of data acquisition(user interaction data and user eye tracking data)and visualization in virtual reality environment are studied,and integrated into a framework of data acquisition and visualization suitable for virtual reality environment.2.From the perspective of theoretical validation,based on the existing theory of visual variables,combined with virtual reality experimental platform and user cognitive experimental methods,the visual variables such as color,size and spatial posture are preliminarily explored,and the applicability of visual variables of two-dimensional map symbols in three-dimensional model is analyzed.3.According to the preliminary validation experiments of visual variables and the knowledge of color mapping theory,this paper extensively studies the visual variables such as color,transparency and illumination.According to user cognitive experiments,the general process of visual variable mapping is summarized,and constructing a visual variable mapping model for three-dimensional models.