Fig 1.
Case study area: China’s administrative boundaries at different levels.
Fig 2.
Flowchart of the proposed urban extents extraction model.
Fig 3.
Urban extents of cities in China extracted in this study.
(a) the Beijing-Tianjin-Tangshan district, (b) the Pearl River Delta, (c) the Yangtze River Delta, (d) Urumqi in the Xinjiang Uygur Autonomous Region, (e) Zhengzhou in Henan Province.
Table 1.
Accuracy assessment of urban extents in 2000 extracted at county scale.
Table 2.
Accuracy assessment of the extracted urban extents at the county, municipal, and provincial scales in 2000.
Fig 4.
Trend of the urban area series in China.
Fig 5.
Offset in the extracted urban extents of Beijing in 2008 and 2009.
(a) The result for 2008 is superimposed on the result for 2009; (b) The result for 2009 is superimposed on the result for 2008.
Fig 6.
(a) The difference is not more than 1; (b) The difference is not more than 3; (c) The difference is not more than 5; (d) The difference is not more than 7.
Table 3.
Accuracy assessment of the extracted urban extents using different P values in 2000.
Fig 7.
Trend of the urban area series in China.
(A) The urban area using the raw NTL dataset and the proposed temporal and spatial normalization; (B) The urban area using the intercalibrated NTL dataset and the proposed temporal and spatial normalization.
Table 4.
Accuracy assessment of the extracted urban extent at the county in 2000 using different datasets.
Fig 8.
Spatial distribution of analysis on the urban sprawl pattern in China.
Fig 9.
Analysis of urban sprawl in Beijing.
(a) The urban extents in Beijing; (b) Curves displaying the area and ratio of urban sprawl in Beijing; (c) Curves displaying the rate and acceleration of urban sprawl in Beijing.
Fig 10.
Analysis of urban sprawl in Guangzhou.
(a) The urban extents in Guangzhou; (b) Curves displaying the area and ratio of urban sprawl in Guangzhou, (c) Curves displaying the rate and acceleration of urban sprawl in Guangzhou.