基于QuickBird的城市建筑景观格局梯度分析

A gradient analysis of urban architecture landscape pattern based on QuickBird imagery

研究城市建筑景观的梯度变化特征,对城市规划与管理的合理调整有着重要的意义。应用QuickBird影像,基于Barista软件提取了建筑物三维信息,采用建筑平均高度、建筑密度、容积率、建筑高度标准差、建筑体形系数等指标,结合梯度分析法研究了铁西区建筑景观格局的梯度变化。结果表明:从1997到2008年,低层与多层建筑是主要的建筑景观组分,平房与低层建筑占地面积比重显著下降,多层、中高层与高层建筑比重上升。建筑平均高度、容积率与建筑高度标准差逐年上升,建筑密度、建筑体形系数与景观形状指数下降。建筑向垂直方向扩展,建筑能耗降低,形状更加规则。建筑景观的梯度变化与距市中心距离的远近没有关系,与区域功能相关,商业区建筑平均高度与容积率最高,政府所在地范围内建筑密度最大。

The gradient analysis is useful in proposing reasonable adjustments for urban planning and management of urban architecture landscape. It was mainly studied that the whole and gradient variation characteristic of architecture landscape in a three-dimensional space in the Tiexi District, Shenyang, China, during the urban renewal process in this paper. In this research, the three-dimensional information of buildings was extracted from aerial photos （1997） and QuickBird imageries （2002, 2005 and 2008） based on ArcGIS and Barista software separately, and the height accuracy of building extraction was 2.66m. All buildings were divided into six types according to the height （H）： Bungalow （H≤ 4m）, Low-rise building （4m〈H≤10m）, Muti-story building （ 10m〈H≤ 19m）, Mid-tall story building （ 19m〈H≤30m）, High-rise building （30m〈H≤100m） and Super-high building （H〉 100m）. Seven indexes （average building height, landscape height standard deviation, floor area ratio, building shape coefficient, building coverage ratio, patch density and landscape index shape） were used to study the variation in architecture landscape pattern in the Tiexi District. To detect the gradient variation in architecture landscape pattern in a three-dimensional space, we conducted a northeast-southwest transect cutting across the study area from the center to outskirt of the city. The transect had three adjacent rows each composed of twenty-four 300x300m blocks. The orientation of the transect was chosen to include the first ring road area, government building area, second ring road area, commercial district, public garden and third ring road area. The four indexes （average building height, floor area ratio, building coverage ratio and building shape coefficient） were computed along a 7.2km long and 0.9km wide transect with 3 ×3 （ i. e. , 900×900m） and 1×1 （ i. e. , 300×300m） overlapping moving window, separately. The results showed that low-rise and multi-story buildings were the dominant architecture landscape types from 1997 to 2008. The area ratio of bungalow and low-rise building declined, whereas, multi-story, mid-tall story and high-rise building increased. The value of average building height, floor area ratio and building height standard deviation was increasing year by year, as building coverage ratio, building shape coefficient and building shape index was decreasing. Buildings were growing in the vertical direction. The energy consumption of buildings was decreased and the building shape became more regular. The gradient change of architecture landscape was not related to the distance to the urban center, but to the regional function. Commercial district has the highest average building height and floor area ratio. The government building area has the highest building coverage ratio. The size of the moving window didn＇t have influence on the variation characteristic in architecture landscape pattern along the transect. For the four indexes in the gradient analysis, both size of the moving window with a fairly similar trend, but the small size presented big fluctuation. The implementation of urban renewal policies and transformation of regional function were the main factors for variation in architecture landscape pattern in Tiexi District from 1997 to 2008.