| 引用本文: | 张毅,陈成忠,吴桂平,范兴旺,潘鑫,刘元波.遥感影像空间分辨率变化对湖泊水体提取精度的影响.湖泊科学,2015,27(2):335-342. DOI:10.18307/2015.0219 |
| ZHANG Yi,CHEN Chengzhong,WU Guiping,FAN Xingwang,PAN Xin,LIU Yuanbo.Effects of spatial scale on water surface delineation with satellite images. J. Lake Sci.2015,27(2):335-342. DOI:10.18307/2015.0219 |
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| 摘要: |
| 湖泊面积是表征湖泊水情变化的重要指示因子,如何从不同空间分辨率遥感数据中获取客观准确的水面信息,是当前遥感应用研究中的难点问题.本文以鄱阳湖为例,通过选用丰水期和枯水期代表性Landsat ETM+遥感影像,采用最邻近法(NN)和像元聚合法(PA)两种重采样方法,分别获取分辨率逐渐降低的不同分辨率的影像数据,结合归一化差异水指数法研究水域面积随遥感影像分辨率降低的变化趋势及其误差变化特征,同时深入分析不同影响因素对水体提取精度的差异.研究结果表明:(1) 空间分辨率是影响鄱阳湖水体提取精度的重要因素之一,随着遥感影像空间分辨率的降低,提取水域面积的精度相对30m分辨率时呈逐渐降低的趋势,但整体精度较高,最低精度在67.64%以上;(2) NN重采样方法对遥感影像波段亮度值的均值影响不大,但PA重采样后影像的均值和标准差随分辨率逐渐降低且变化更有规律;(3) 水体阈值在PA重采样后变化较大,NN重采样后变化较小,因而采用30m分辨率时获取的阈值提取PA重采样后鄱阳湖水体误差较大,提取NN重采样后的湖泊水体误差较小.本研究结果对于全球变化影响下湖泊水体信息遥感精确提取具有重要的参考价值. |
| 关键词: 遥感 分辨率 阈值 重采样 NDWI 鄱阳湖 |
| DOI：10.18307/2015.0219 |
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| 基金项目:中国科学院南京地理与湖泊研究所"一三五"战略发展规划项目(NIGLAS2012135001)、国家重点基础研究发展计划"973"项目(2012CB417003)和中国科学院择优支持项目联合资助. |
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| Effects of spatial scale on water surface delineation with satellite images |
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ZHANG Yi1,2, CHEN Chengzhong1, WU Guiping2, FAN Xingwang2, PAN Xin2, LIU Yuanbo2
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1.College of Urban and Environmental Sciences, Hubei Normal University, Huangshi 435002, P. R. China;2.Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, P. R. China
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| Abstract: |
| Lake area is an important indicator for lake-related research.Accurate extraction of water surface from remote sensing images with various spatial resolutions still remains unsettled.To investigate the effects of spatial resolution on lake surface monitoring, two Landsat ETM+(Enhanced Thematic Mapper Plus) images were acquired with one at high water level and the other at low water level.These images were resampled to lower resolutions using Nearest Neighboring(NN) and Pixel Aggregation(PA) methods, and extracted for water surface area using NDWI(Normalized Difference Water Index) thresholding method.Variation trend and error distribution of water surface area with spatial resolution were thoroughly investigated.In addition, the influence of different factors on water surface extraction was discussed.The main conclusions are as follows:(1) the accuracy decreases gradually at lower spatial resolution relative to 30m resolution.However, the overall accuracy is higher with a minimum of 67.64%;(2) NN has minor impact on DN values, whereas PA reduces mean digital number values and standard values.The reduction is gradual and smoother than NN;and(3) the threshold varies for PA and remains stable for NN.Thus, use of threshold determined on 30m image should introduce larger errors for PA-resampled images than NN-resampled images.This study provides invaluable guidance for water surface mapping using remote sensing methods under global changes. |
| Key words: Remote sensing spatial resolution threshold resampling NDWI Lake Poyang |
