地球信息科学学报 ›› 2012, Vol. 14 ›› Issue (1): 94-100.doi: 10.3724/SP.J.1047.2012.00094

• 地理信息系统技术应用 • 上一篇    下一篇

基于数字高程模型的城市地表开阔度研究——以南京老城区为例

贺文慧, 杨昕*, 汤国安, 周毅   

  1. 南京师范大学虚拟地理环境教育部重点实验, 南京 210046
  • 收稿日期:2011-07-13 修回日期:2011-12-09 出版日期:2012-02-25 发布日期:2012-02-24
  • 通讯作者: 杨昕(1976-),女,博士,副教授,主要从事数字地形分析和空间分析。E-mail:xxinyang@163.com. E-mail:xxinyang@163.com.
  • 作者简介:贺文慧(1988-),女,硕士研究生,主要从事城市数字高程模型及地形分析。E-mail:waixinmaozi@163.com
  • 基金资助:

    教育部高等学校博士点基金(20093207120008),国家自然科学基金项目(40901185),江苏省高校优势学科建设工程资助项目。

Research on Sky View Factor in Urban Area Based on Urban Digital Elevation Model:A Case Study of Nanjing Old City

HE Wenhui, YANG Xin*, TANG Guoan, ZHOU Yi   

  1. Key laboratory of Virtual Geographic Environment, Ministry of Education, Nanjing Normal University, Nanjing 210046, China
  • Received:2011-07-13 Revised:2011-12-09 Online:2012-02-25 Published:2012-02-24

摘要: 城市地表开阔度是对地表形态开阔程度的定量描述,间接反映了通风、日照等城市物理性能。本文基于城市数字高程模型,以自然地形较为起伏的丘陵城市——南京为例,采用以光线追踪算法为核心的栅格计算模型,对南京老城区的地表开阔度进行了计算,并以典型样区分析和街区统计为方法,综合分析了建筑与自然地形对城市地表开阔度的影响,结果表明:南京老城区公共绿地、广场以及文物古迹用地的地表开阔度相对较高,均大于0.8,社区中心和居住用地的地表开阔度相对较低,均小于0.6,突出特点是居住用地地表开阔度小于金融商业用地。地表开阔度相对较低的街区主要临近主干道,形成较为明显的西北——东南方向分布的条带状特征,整体呈现出中心条带低四周高的宏观特征。

关键词: 城市数字高程模型, 地表开阔度, 光线追踪算法, 南京市老城区

Abstract: The sky view factor (SVF) has been commonly used to describe the shadow impaction of visualization or sunshine from neighborhood buildings or terrains in urban area. It reflects the influences of urban geometry on the microclimate in an urban area. Firstly, we provided a comprehensive review of SVF analysis both in natural terrain and urban area studies. Then we presented a simulation approach based on shadow casting algorithm to calculate continuous SVF values. And, using raster-based data model we analysed the effect of sun shadow shading by neighbor buildings, simulated solar radiation for many times by continuing translation of the solar altitude and azimuth and calculated whether cells were in shadow. The ratio of simulation times and the times of a cell in shadow is considered as an approximate value of SVF. An ArcGIS-embedded computer program is developed and a SVF map for entire area is generated by using high resolution urban digital elevation model of Nanjing old city. Some areas representing different land use types in Nanjing old city are selected for analysis of the small-scale spatial variation of the SVF. The result illustrates that SVF decreases as building height raises or building quantity increases. Mean, maximum, minimum and standard deviation of SVF for each land use category within Nanjing old city are calculated and they are significantly different in different areas. The mean SVF values occurring in parks, open space and areas of historical and cultural value are higher than those of other land use types, which are more than 0.8. The mean SVF values occurring in community centers and residential areas are lower than those of other land use types, which are lower than 0.6. One of the most noticeable results is the unexpectedly higher mean SVF value in commercial areas than that in residential area in Nanjing old city. Meanwhile, spatial distribution pattern of SVF is derived by regarding block as a basic statistical unit. The mean values in the city centre are high while that in urban fringe are usually low. The blocks with high values line up in a northwest to southeast alignment, which may have an effect on urban microclimate.

Key words: urban digital elevation model, sky-view factor, ray-tracing algorithm, Nanjing old city