Evaluation on the two filling functions for the recovery of forest information in mountainous shadows on Landsat ETM + Image

In general,topographic shadow may reduce performance of forest mapping over mountainous regions in remotely sensed images.In this paper,information in shadow was synthesized by using two filling techniques,namely,roifill and imfill,in order to improve the accuracy of forest mapping over mountainous regions.These two methods were applied to Landsat Enhanced Thematic Mapper (ETM +) multispectral image from Dong Yang County,Zhejiang Province,China.The performance of these methods was compared with two conventi...     

基于ETM+的植被覆盖信息提取及其动态变化分析——以广州市为例

以2000年和2005年ETM+影像为数据源,在水体掩膜和端元光谱优选对比基础上,利用线性光谱模型提取了广州市植被覆盖信息,并对植被覆盖信息的时空动态变化进行了定量分析,结果表明:应用线性光谱模型之前对所占面积不大的水体进行处理是非常必要的,选取植被、硬化地面、土壤三端元法比包含阴影的四端元法更有利于线性光谱分离,而且能达到很高的精度;此外,通过对植被覆盖信息空间结构和景观格局的研究,显示:2000-2005虽然广州市绿化取得了初步成效,但总体植被覆盖状况呈下滑趋势,植被景观破碎程度增加,各植被景观形状趋于复杂化,城市化的发展加之人类活动的干扰,低植被覆盖区不断扩大,而中、高植被覆盖区正处于不断退化时期。     

基于多源遥感数据的水体信息提取研究

卫星遥感技术已被广泛应用到水体信息提取中,但目前基于遥感技术的水体信息提取多采用单一的遥感数据源,而没有充分利用多源数据的信息复合优势,因此,提取结果经常受天气气候或空间分辨率限制。本文研究了不同尺度、不同平台的多种遥感数据源的水体信息提取方法。首先,基于波谱间关系决策树分类算法对Landsat ETM+图像进行水体提取,利用其分辨率优势较准确地提取出水体范围;其次,在Radarsat SAR图像上利用阈值法粗提取水体信息后,结合DEM剔除阴影得到水体信息;最后,利用灾前Landsat ETM+图像水体信息提取结果和灾中Radarsat SAR图像水体信息提取结果,进行差值处理,得到洪水淹没范围。研究结果可以为洪水灾害监测与评估提供信息依据。     

Comparison between four methods for data fusion of ETM+ multispectral and pan images

Four data fusion methods, principle component transform (PCT), brovey transform (BT), smoothing filter-based intensity modulation (SFIM), and hue, saturation, intensity (HSI), are used to merge Landsat—7 ETM+ multispectral bands with ETM+ panchromatic band. Each of them improves the spatial resolution effectively but distorts the original spectral signatures to some extent. SFIM model can produce optimal fusion data with respect to preservation of spectral integrity. However, it results the most blurred and noisy image if the coregistration between the multispectral and pan images is not accurate enough. The spectral integrity for all methods is preserved better if the original multispectral images are within the spectral range of ETM+ pan image.     

Retrieval of suspended sediment concentrations in large turbid rivers using Landsat ETM+: an example from the Yangtze River,China

Suspended sediment concentration (SSC) is a critical parameter in the study of river sediment transport and water quality variation, but traditional measurement methods are costly and time‐consuming. This paper is focused on presenting a methodology that may be useful in estimating SSC which is of key importance in process geomorphology and hydrology. In previous studies, remote sensing has been applied to estimate the SSC of sea waters as well as low turbid inland waters like lakes, reservoirs and short river reaches visible within a single Landsat satellite image coverage. Rivers, especially highly turbid large rivers, have largely been ignored. The dataset used in this paper includes measured SSC and multi‐temporal Landsat ETM+ images covering most part of the Yangtze River. Using an effective easy‐to‐use atmospheric correction method that does not require in situ atmospheric conditions, retrieved water reflectance of Band 4 was found to be a good SSC indicator within the large SSC range 22–2610 mg l^–1. The newly developed regression relation between SSC and water reflectance of Band 4 appears to be able to provide a relatively accurate SSC estimate directly from Landsat ETM+ images for the Yangtze River from the upper, the middle to the lower reaches. With the relation it is possible to estimate or map out SSC dynamics of large rivers which lack SSC data due to constraints of conventional measurements. Copyright © 2009 John Wiley & Sons, Ltd.     

基于规则的多种类型海岸线TM/ETM+影像智能检测方法

A coastline is defined as the average spring tide line. Different types of seacoast, such as sandy, silty, and bio- logical coast, have different indicators of interpretation. It is very difficult to develop a universal method for interpreting all shorelines. Therefore, the sandy, the silty, and the biological coast are regarded as research objects, and with data mining technolog,found the rules of interpretation of those three types of coastlines. Then, an intelligent coastline interpretation method based on rules was proposed. Firstly, the rules for ex- tracting the waterline in Landsat TM/ETM＋ （Thematic Mapper/Enhanced Thematic Mapper Plus） imagery were discovered. Then, through analyzing the features of sandy, silty and biological coast, the indicators of interpreting different types of shoreline were determined. According to the indicators, the waterline could be corrected to the real coastline. In order to verify the validity of the proposed algorithms, three Landsat TM/ETM＋ imageries were selected for case studies. The experimental results showed that the proposed methods could interpret the coastlines of sandy; silty, and biological coasts with high precision and without human intervention, which exceeded three pixels.     

基于决策树的Landsat TM/ETM+图像中太湖蓝藻水华信息提取

以9期Landsat TM/ETM+影像为数据源,基于K-T变换和归一化植被指数(NDVI),建立了湖泊蓝藻水华信息提取的决策树模型.基于大气顶面反射率图像,选用2005年10月17日太湖图像进行了对比验证,表明决策树模型比单波段阈值法、多波段阈值法(RVI、DVI、NDVI)能够更有效地提取蓝藻水华信息,区分陆生植被、水生植物和水华,省去了水体掩膜的过程.使用太湖2002年10月25日和2011年7月22日图像、巢湖2005年8月12日的图像,验证决策树模型方法和工作流程的有效性.使用多期TM图像确定了阈值的取值范围,其中,亮度、绿度、NDVI的下限值依次为0.191、-0.007、-0.054,湿度下限范围为0.07~0.15;亮度阈值上限范围为0.3~0.7、绿度为0.2~0.5、湿度为0.1~0.3,这些结果可作为湖泊蓝藻水华遥感监测的参考.     

基于ETM+影像的福州市部分城区的地表温度反演与分析

以福州市部分地区为研究对象,采用Landsat ETM+第6波段的单窗算法,进行地表温度反演得出地表温度分布图,分析了研究区总体温度分布的特点、研究了三种下垫面类型的温度分布差异及与NDVI的关系、同时对生活建筑区分别取样进行了对比分析。结果表明:研究区中心热岛效应显著;研究区不同的土地覆盖类型地表温度有显著差异,从高到低为,生活建筑区自然表面水体;地表温度与归一化植被指数(NDVI)有良好的负相关关系;相同土地覆盖类型开发程度不同,温度也存在差异,此差异小于不同土地覆盖类型之间的温度差。     

地形效应校正的遥感地热异常提取

在山地复杂地形条件下,利用热红外遥感获得的地表温度分布显著受到地形的影响,真实的地热异常信息往往难以识别,热红外遥感应用于山区地热勘探受到极大限制。以广东龙川地热勘查区为研究区,初步探讨了山地环境中如何抑制地形效应,以有效提取地热异常。首先,基于Landsat ETM+遥感数据反演地表温度,分析坡向和坡度两个地形因子与地表温度的关系;然后,在此基础上,将研究区的地表温度按坡向分成3个子区(阳坡、过渡坡和阴坡),根据阳坡地表温度与坡向的线性拟合关系将其校正到水平坡度上;最后,结合地质构造分布和地表覆被情况,在3个子区识别了4处地热异常,并与已知地热点进行比较验证。结果表明:坡向分区和阳坡坡度校正能够有效抑制地形效应,提高遥感地热异常识别精度,为山区地热资源的预测评价提供新思路。     

西藏沙莫棍巴地区资源潜力遥感综合预测研究

文章以西藏自治区沙莫棍巴地区为研究区,针对高寒山区的自然地理条件,利用ETM＋多光谱遥感数据,在充分分析遥感影像特征的基础上,参考已有的区域地质矿产资料,对研究区的地层、岩体、含矿层位、控矿构造和蚀变带（体）进行了遥感地质解译,以及资源潜力综合预测研究,提出了7处找矿预测区,为该区尽快开展地质矿产勘查工作,提高找矿效率,提供了科学依据和目标地。