Validity and feasibility of a satellite imagery-based method for rapid estimation of displaced populations.
Validity and feasibility of a satellite imagery-based method for rapid estimation of displaced populations.
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DOI：
10.1186/1476-072x-12-4
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发表时间：
2013-01-23
影响因子：
4.9
通讯作者：
Grundy C
中科院分区：
文献类型：
--
作者：
Checchi F;Stewart BT;Palmer JJ;Grundy C
估计被迫流离失所人口的规模对于记录他们的困境并为他们的援助分配足够的资源至关重要，但由于方法上的挑战和交通不便，往往无法做到这一点，特别是在流离失所的严重阶段。在这项研究中，我们探索了使用超高分辨率卫星图像来远程估计被迫流离失所人口的潜在用途。我们的方法包括乘以（i）卫星图像上假设的住宅结构的手动计数和（ii）从公开报告中获得的每个结构的平均人数（结构占用率）的估计值。我们计算了孟加拉国、乍得、刚果民主共和国、埃塞俄比亚、海地、肯尼亚和莫桑比克 11 个地点（六个难民营、三个境内流离失所者营地和两个居民和流离失所者混合的城市社区）的人口估计数，范围从 1,969 人到 90,547 人，并将这些数据与人口普查或其他可靠方法得出的“黄金标准”参考人口数据进行比较。独立分析师的结构计数相当一致。每个地点提供 1 到 11 份占用报告，其中大多数报告的是每个家庭而不是每个建筑物的人数。基于图像的方法相对于参考人口数字的精度在四个地点低于 10%，在三个地点低于 10-30%，但严重高估了居住数据不可信的埃塞俄比亚营地和住宅布局密集且复杂的海地两个震后地点的人口。对于每个站点，估算在 2-5 个工作日内完成。在具有明显可区分的个体结构的环境中，基于图像的远程方法对于快速估计的目的具有合理的准确性，并且实施起来简单且快速，并且在当前的应用中可能会表现得更好。然而，在具有相互连接的建筑物或庇护所、复杂的屋顶图案和多层建筑的环境中，它可能具有难以克服的局限性。根据这些结果，我们讨论了该方法开发的可能途径。
Estimating the size of forcibly displaced populations is key to documenting their plight and allocating sufficient resources to their assistance, but is often not done, particularly during the acute phase of displacement, due to methodological challenges and inaccessibility. In this study, we explored the potential use of very high resolution satellite imagery to remotely estimate forcibly displaced populations. Our method consisted of multiplying (i) manual counts of assumed residential structures on a satellite image and (ii) estimates of the mean number of people per structure (structure occupancy) obtained from publicly available reports. We computed population estimates for 11 sites in Bangladesh, Chad, Democratic Republic of Congo, Ethiopia, Haiti, Kenya and Mozambique (six refugee camps, three internally displaced persons’ camps and two urban neighbourhoods with a mixture of residents and displaced) ranging in population from 1,969 to 90,547, and compared these to “gold standard” reference population figures from census or other robust methods. Structure counts by independent analysts were reasonably consistent. Between one and 11 occupancy reports were available per site and most of these reported people per household rather than per structure. The imagery-based method had a precision relative to reference population figures of <10% in four sites and 10–30% in three sites, but severely over-estimated the population in an Ethiopian camp with implausible occupancy data and two post-earthquake Haiti sites featuring dense and complex residential layout. For each site, estimates were produced in 2–5 working person-days. In settings with clearly distinguishable individual structures, the remote, imagery-based method had reasonable accuracy for the purposes of rapid estimation, was simple and quick to implement, and would likely perform better in more current application. However, it may have insurmountable limitations in settings featuring connected buildings or shelters, a complex pattern of roofs and multi-level buildings. Based on these results, we discuss possible ways forward for the method’s development.