Li Hao, Yao Weiqi, Zhang Mengru, Yang Xiaoyue, Wang Qian
School of Geography and Environment, Liaocheng University, Liaocheng, 252059, China.
Liaocheng Innovative High Resolution Data Technology Co., Liaocheng, 252059, China.
Sci Rep. 2025 Jan 2;15(1):202. doi: 10.1038/s41598-024-81566-w.
Keyhole imagery documented global surface from 1960 to 1980s and has contributed to earth surface change research, while evaluation of its' coverage spatial heterogeneity is rare. In this work the boundary vectors with attributes of all freely Keyhole images within China were obtained from USGS website to automatically investigate the spatial coverage characteristics using the ArcPy library in Python. Images were categorized into meter-level (C1), five-meter-level (C2), and ten-meter-level (C3). The resolution and spatial coverage distribution of Keyhole imagery at national and provincial levels were investigated using geostatistical and statistical methods. Combining coverage area of free imagery and the costs of non-free imagery, the cost of Keyhole datasets construction was calculated. The results indicated: (1) the coverage of C1, C2, and C3 across China was 58%, 95%, and 76%, respectively. The average number of coverages were 4.9, 4.5, and 3.6 times, respectively, with variation coefficients of 0.7, 1.3, and 1.3. All of C1, C2, and C3 imageries exhibited significant global and local spatial clustering characteristics. (3) The acquisition costs for datasets with triple coverage of C1, C2, and C3 imagery in China were 103, 103, and 23 thousand dollars, respectively. We demonstrated how the large data amount Keyhole imagery that could not analyzed manually were automatically reorganized using the metadata, to facilitate the spatial distribution and cost estimation analysis.
锁眼卫星图像记录了20世纪60年代到80年代的全球地表情况，为地球表面变化研究做出了贡献，然而对其覆盖范围空间异质性的评估却很少见。在这项工作中，从美国地质调查局网站获取了中国境内所有免费锁眼卫星图像的带有属性的边界矢量，使用Python中的ArcPy库自动研究其空间覆盖特征。图像被分为米级（C1）、五米级（C2）和十米级（C3）。运用地统计学和统计学方法研究了锁眼卫星图像在国家和省级层面的分辨率及空间覆盖分布情况。结合免费图像的覆盖面积和非免费图像的成本，计算了锁眼数据集构建的成本。结果表明：（1）C1、C2和C3在中国的覆盖范围分别为58%、95%和76%。平均覆盖次数分别为4.9次、4.5次和3.6次，变异系数分别为0.7、1.3和1.3。C1、C2和C3图像均呈现出显著的全球和局部空间聚类特征。（3）在中国，C1、C2和C3图像三重覆盖的数据集获取成本分别为10.3万美元、10.3万美元和2.3万美元。我们展示了如何利用元数据自动重组无法手动分析的大量锁眼卫星图像数据，以促进空间分布和成本估算分析。
