基于街景影像的城市道路空间舒适度研究

Approach to Quantify Spatial Comfort of Urban Roads based on Street View Images

城市道路空间舒适度是综合刻画城市道路环境的量化指标之一,可为城市道路规划建设、城市交通优化、城市环境评估等提供参考。本文以街景影像为基础数据,从空间视角阐述了城市道路空间舒适度内涵,构建了城市道路空间舒适度量化指标,建立了以语义分割和等距采样为基础的城市道路空间舒适度测度方法和空间插值方法,最后以南京市局部城区为样区进行了实验,并分析了城市道路空间舒适度特征。实验结果表明:(1)语义分割中主要要素的分割精度满足要求,分割总体精度为84.92%,Kappa系数为80.06%;(2)综合考虑数据处理时间和舒适度量化表达程度,200 m采样间距可以综合描述研究区道路空间舒适度状态;(3)本文提出的双向约束插值方法可消除突变点、梯形插值形态、花斑状纹理等异常插值现象,同时可有效保持道路空间舒适度方向特征;(4)本文提出的测度方法可以有效度量城市道路空间舒适度,测度等级精度达80%;(5)城市道路空间舒适度等级与道路等级整体上呈现正相关关系,且舒适度在实验区呈现南高北低、建邺区较高、鼓楼及历史老城区低的空间分布状态。

Urban road spatial comfort is an useful indicator to comprehensively quantify urban road environment, which plays an important role in urban-related researches such as construction planning,environment assessment, and traffic optimization. Based on the data of street view images, firstly, the concept of urban road spatial comfort is defined from the perspective of space vision. To represent the concept accurately,five quantitative indexes including road unobstructed degree, road spaciousness, greening degree of vegetation,proportion of sky view, and space openness, and a model to quantify urban road spatial comfort are constructed.Secondly, the urban road spatial comfort measurement method is established. To establish the model, an approach that comprehensively combines the semantic segmentation of street view images, weight assignment based on entropy weight, and analytic hierarchy process and dual-constrained interpolation is designed. Finally,we take the local urban area of Nanjing as the experimental area to assess the performance of the proposed approach. The results show that(1) The segmentation accuracy of the main elements meets the requirements,with an overall segmentation accuracy of 84.92% and a Kappa coefficient of 80.06%;(2) The 200-m sampling distance can comprehensively reflect the road spatial comfort degree in the study area considering the processing time and the quantitative expression;(3) The dual-constrained interpolation method proposed in this paper can eliminate the abnormal interpolation phenomena such as abrupt point, trapezoid shape, and disordered texture,and effectively maintain the directional characteristics of road spatial comfort;(4) The method proposed in this paper can effectively measure the urban road spatial comfort with an accuracy above 80%;(5) There is a positive correlation between the spatial comfort degree and the road grade, that is to say, the higher the road grade, the higher proportion of high-degree spatial comfort in roads. The spatial comfort of urban roads in the experimental area is higher in the south and lower in the north and is higher in Jianye district and lower in Gulou and historical old urban area.