基于3DGIS的机动车尾气扩散模拟和体视化研究

Diffusion Simulation and Volume Visualization of Vehicle Exhaust Based on 3DGIS

在城市中,空气污染物的主要来源是机动车尾气,探求城市机动车尾气扩散规律并积极寻求改善措施已成为许多城市迫在眉睫的问题。目前对机动车尾气扩散模拟的研究较多,但对扩散过程建模和体视化分析的研究较少。为此,提出了一个基于3DGIS的机动车尾气扩散建模和可视化框架。首先,在3DGIS中完全整合CALINE4(California line source dispersion model-4)模型,用连续场模型表达动态扩散过程,在语义空间建立统一数据模型表示建筑、道路、树木以及动态扩散过程数据;其次,采用基于GPU(graphics processing unit)的直接体绘制方法对过程数据进行可视化分析,重点优化梯度计算、体纹理重采样和动态插值等关键算法,动态表达机动车尾气的扩散过程;最后,通过北京地区一条典型的道路机动车尾气扩散实验,检验了该方法的可靠性和高效性。

In cities,the main source of air pollutants is vehicle exhaust.It has become an urgent problem for many cities to explore the law of vehicle exhaust diffusion and actively seek for improvement measures.At present,there are many researches on the simulation of vehicle exhaust diffusion,but few on the modeling of diffusion process and volume visualization analysis.This paper integrates California line source dispersion model-4(CALINE4)model and 3 DGIS to solve the problem of urban vehicle exhaust diffusion simulation and dynamic visualization.Firstly,a street-scale framework of vehicle exhaust diffusion simulation and visualization is established,and a continuous concentration field is established to express the diffusion processing.A unified data model is used in the semantic space to integrate the data of buildings,roads,trees and dynamic diffusion process data.Secondly,a graphics processing unit-based direct volume rendering method is used to visualize the dynamic diffusion data,and this algorithm is improved in real-time gradient calculation,texture sampling and time-based interpolation.Finally,this paper analyzes the vehicle exhaust diffusion of a road in the central business district area of Beijing.The experimental results show that the coupling application of 3 DGIS and CALINE4 model can better reveal the spatial and temporal distribution characteristics of urban vehicle exhaust and concentration,which verifies the reliabless and efficiency of the proposed method.