Journal of Geo-information Science >
Three-dimensional Urban Gravity Center Calculation Method and Empirical Research: A Case Study of Nanjing
Received date: 2014-07-10
Request revised date: 2014-08-06
Online published: 2015-03-10
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The current studies on urban gravity center mainly focus on two-dimensional urban gravity center that based on the planar form. Now the trend of urban vertical expansion is more and more distinctive, it is necessary to research the calculation method and analyze the variation of three-dimensional urban gravity center. Based on the analysis of the calculation method of two-dimensional gravity center, this paper deduces a new method to calculate the three-dimensional urban gravity center. It takes three-dimensional urban space as a combination that is formed by multiple stacked layers of ‘sheet’, and uses the mathematical formula of this combination’s gravity center to calculate the three-dimensional urban gravity center. Taking Nanjing as an experimental area for validation, we calculate the two-dimensional and three-dimensional urban gravity centers respectively and contrasts their changing trails. The result shows that the method proposed in this paper is easy to obtain urban entity’s three-dimensional gravity center. Also, the position of the three-dimensional urban gravity center obtained in this way is correct. Through the analysis of the variation law of the two-dimensional and the three-dimensional urban gravity centers in Nanjing, the projections of the two gravity centers have similar changing characteristics and regularities, but a certain degree of deviation between the two trails. The direction of deviation evidently corresponds to the dense regions of high-rise buildings. Taking full account of the urban expansion in the vertical direction, the three-dimensional urban gravity center provides an effective way in reflecting the characteristics and regularities of urban spatial change.
Key words: urban space; three-dimensional gravity center; calculation method; Nanjing
QIAO Weifeng , LIU Yansui , WANG Yahua , XIANG Lingzhi . Three-dimensional Urban Gravity Center Calculation Method and Empirical Research: A Case Study of Nanjing[J]. Journal of Geo-information Science, 2015 , 17(3) : 268 -273 . DOI: 10.3724/SP.J.1047.2015.00268
Fig. 1 Flowchart of extraction technique of the three-dimensional urban gravity center图1 城市三维重心提取技术路线图 |
Fig. 2 The spatial gravity center of plane geographic object图2 平面地理对象的空间重心 |
Fig. 3 The schematic diagram of three-dimensional urban gravity center calculated from building height contours图3 建筑高度等值线城市三维重心计算原理示意图 |
Tab. 1 The shift direction and distance of the two-dimensional gravity center表1 二维平面重心转移方向与距离 |
年份 | 平面重心位置 | 移动距离(m) | 转移方向(°) | 扩张方向 |
---|---|---|---|---|
1980 | 鼓楼广场北侧 | |||
1990 | 火车站西侧 | 2751 | 73.04 | NE |
2000 | 北极阁公园北侧 | 2625 | 276.32 | SE |
2004 | 华山饭店西侧 | 1599 | 303.69 | SE |
2008 | 西安门 | 1291 | 281.86 | SE |
2012 | 新街口东侧 | 1564 | 186.10 | SW |
Fig. 4 The three-dimensional sketch of building height contours in Nanjing in 2012图4 2012年南京市建筑高度等值线三维示意图 |
Fig. 5 The change of three-dimensional center in Nanjing图5 南京市三维重心变化 |
Tab. 2 The shift direction and distance of three-dimensional gravity center表2 三维重心转移方向与距离 |
年份 | 三维重心在平面的投影位置 | 三维重心的高度(m) | 平面投影点转移距离(m) | 平面投影点转移方向(°) | 三维重心扩张方向 |
---|---|---|---|---|---|
2000 | 鼓楼广场东侧 | 2.40 | |||
2004 | 大行宫 | 2.47 | 2041 | 291.93 | SE |
2008 | 西安门南侧 | 2.45 | 863 | 303.06 | SE |
2012 | 新街口南侧 | 2.51 | 1637 | 182.97 | SW |
Fig. 6 Comparison between the two-dimensional and three-dimensional gravity centers in Nanjing图6 南京市的二、三维重心变化对比图 |
The authors have declared that no competing interests exist.
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