Integrating spectral and non-spectral data to improve urban settlement mapping in a large Latin-American city     

Feilin Lai 《地理信息系统科学与遥感》2020,57(6):830-844

ABSTRACT

Information on urban settlements is crucial for sustainability planning and management. While remote sensing has been used to derive such information, its applicability can be compromised due to the complexity in the urban environment. In this study, we developed a remote sensing method to map land cover types in a large Latin-American city, which is well known for its mushrooming unplanned and informal settlements. After carefully considering the landscape complexity there, we designed a data fusion method combining multispectral imagery and non-spectral data for urban and land mapping. Specifically, we acquired a cloud-free Landsat-8 image and two non-spectral datasets, i.e., digital elevation models and road networks. Then, we implemented a set of experiments with different inputs to evaluate their merits in thematic mapping through a supervised protocol. We found that the map generated with the multispectral data alone had an overall accuracy of 73.3% but combining multispectral imagery and non-spectral data yielded a land cover map with 90.7% overall accuracy. Interestingly, the thermal infrared information helped substantially improve both the overall and categorical accuracies, particularly for the two urban classes. The two types of non-spectral data were critical in resolving several spectrally confused categories, thus considerably increasing the mapping accuracy. However, the panchromatic band with higher spatial resolution and its derived textural measurement only generated a marginal accuracy improvement. The novelties of our work are with the successful separation between the two major types of urban settlements in a complex environment using a carefully designed data fusion approach and the insight into the relative merits of the thermal infrared information and non-spectral data in helping resolve the issue of class ambiguity. These findings should be valuable in deriving accurate urban settlement information which can further advance the research on socio-ecological dynamics and urban sustainability.  相似文献   

A Holistic Approach to Upwelling and Downwelling along the South-West Coast of India     

Phiros Shah  R. Sajeev  K. J. Thara  Grinson George  Muhammad Shafeeque  S. Akash 《Marine Geodesy》2019,42(1):64-84

An attempt has been made to develop a holistic understanding of upwelling and downwelling along the south-west coast of India. The main objective was to elucidate the roles of different forcings involved in the vertical motion along this coast. The south-west coast of India was characterized by upwelling during the south-west monsoon (May to September) and by downwelling during the north-east monsoon and winter (November to February). The average vertical velocity calculated along the south-west coast from the vertical shift of the 26?°C isotherm is 0.57?m/day during upwelling and 0.698?m/day during downwelling. It was concluded that upwelling along the south-west coast of India is driven by offshore Ekman transport due to the alongshore wind, Ekman pumping, horizontal divergence of currents and by the propagation of coastally trapped waves. Whereas downwelling along the coast is driven only by convergence of currents and the propagation of coastally trapped Kelvin waves. Along the west coast of India, the downwelling-favorable Kelvin waves come from the equator and upwelling-favorable waves come from the Gulf of Mannar region.  相似文献   

2017年西藏米林6.9级地震前的热红外异常分析          下载免费PDF全文

张丽峰  王培玲  张朋涛  孙玺皓 《地震工程学报》2020,42(2):360-367

以小波变换和功率谱估计为研究方法,使用中国静止气象卫星热红外亮温数据,研究了2017年11月18日西藏米林MS6.9地震前的热辐射情况。结果发现震前4个月出现热红外异常,其后续演化方向与相关区域的断裂走向非常一致。在8月10日左右异常面积达最大,相对功率谱大于6倍的面积约为20万km^2,9月20日左右消失。分析相同频率2016年同期数据,结果显示在震中周围并未出现显著异常。时序曲线分析表明在8月12日相对功率谱达到峰值,为平均值的20倍,98天后米林地震发生;从7月4日到9月7日,地震当年相对功率谱偏离背景值和标准差,持续时间为65天。西藏地区的强震热红外异常表现出与地热资源分布较为一致的特征及特征周期相对较长的特点,为判定西藏地区的震情积累了一些经验。  相似文献   

FY-3D/MERSI-II全球火点监测产品及其应用   总被引：1，自引：0，他引：1  

郑伟  陈洁  闫华  刘诚  唐世浩 《遥感学报》2020,24(5):521-530

FY-3D/MERSI-II全球火点监测产品主要包括全球范围内的火点位置、亚像元火点面积和火点强度等信息,可用于实时监测全球范围的森林草原火灾、秸秆焚烧等生物质燃烧状况。火点判识算法主要根据中红外通道对高温热源的敏感特性,即含有火点的中红外通道像元辐亮度和亮温较远红外通道的辐亮度和亮温偏高,同时较周边非火点的中红外像元偏高,建立合适的阈值可探测含有火点的像元。亚像元火点面积估算主要使用中红外单通道估算,根据亚像元火点面积估算结果对火点强度进行分级,不同的级别表示不同程度的火点辐射强度。基于全球火点自动判识结果,每日生成0.01°分辨率的卫星遥感日全球火点产品,每月生产0.25°×0.25°格点的全球月火点密度图。在利用FY-3D/MERSI-II火点产品开展的全球火点监测应用中,对多起全球重大野火事件进行了监测,为防灾减灾、全球气候变化研究、生态环境保护等方面提供卫星遥感信息支持。  相似文献   

基于热红外图像的海面油膜面积的测算方法     

王利锋  辛丽平  于波  鞠莲  魏来  胡湛波 《海洋通报》2020,39(6):750-760

针对现有油膜检测技术难以准确测算油膜面积且检测精度受天气条件影响大的问题，本文提出了一种基于热红外图像的海面油膜面积测算方法。采用波段为 8耀14 滋m 的红外热像仪获取海面油膜的热红外图像，对采集的油膜图像进行预处 理 （灰度化、中值滤波和锐化）；基于图像灰度分布特征分割油膜区域 （感兴趣区域，ROI），采用形态学操作对 ROI 进行填充、腐蚀与膨胀，并对 ROI 进行数学表征；通过像素面积法计算 ROI 实际物理面积。实验结果表明：在不同的外界天气环境下 （如海浪、海风、海雾、不同光照等环境），该方法对不同黏度的石油样品在海面形成的油膜均有良好的检测精度， ROI 面积计算平均误差为 3.77%。  相似文献   

红外卫星云图和相关向量机的有眼热带气旋客观定强模型   总被引：1，自引：1，他引：0  

戴李杰  张长江  薛利成  马雷鸣  鲁小琴 《遥感学报》2018,22(4):581-590

热带气旋TC(Tropical Cyclone)是全球影响最严重的自然灾害之一。TC强度和路径的准确预报,对于减轻其带来的灾害影响至关重要。本文基于静止红外卫星云图和相关向量机RVM(Relevance Vector Machine)构建有眼TC客观定强模型。首先,利用高斯平滑对红外卫星云图进行去噪;然后,利用基于测地活动轮廓GAC(Geodesic Active Contour)模型的偏微分方程PDE(Partial Differential Equation)法对有眼TC的眼壁进行分割,提取眼壁的亮温梯度信息,计算眼壁亮温梯度的最大值及梯度数据不同概率时的均值,从而构造与TC强度密切相关的特征因子;最后,利用RVM构建单特征因子、多特征因子与近地面最大中心风速的客观定强模型,研究不同特征维度对TC客观定强误差的影响。实验结果表明,在单特征因子的模型定强中,95%概率眼壁亮温梯度均值的定强误差最小,相比利用单特征因子所构建的定强模型,多特征因子的模型定强误差更小,即多特征因子中包含更多与TC强度相关的特征信息。在多特征因子的模型定强中,二特征因子优于三特征因子模型,说明应当合理选择特征因子维数,并非越多越好。本文所用RVM模型具有良好的高维非线性处理能力,能对TC强度进行有效估计。  相似文献   

An Operational Precipitable Water Vapor Retrieval Algorithm for Fengyun-2F/VISSR Using a Modified Three-Band Physical Split-Window Method     

Juyang HU  Shihao TANG  Hailei LIU  Min MIN 《Journal of Meteorological Research》2019,(2):276-288

The Visible and Infrared Spin-Scan Radiometer(VISSR) onboard the Fengyun-2(FY-2) satellite can provide valuable thermal infrared observations to help create a precipitable water vapor(PWV) product with high spatial and temporal resolutions. The current FY-2/VISSR PWV product in operation is produced by using a traditional two-band physical split-window(PSW) method, which produces low quality results under dry atmospheric conditions. Based on the sensitivity characteristics of FY-2 F/VISSR water vapor channel and two split-window channels to atmospheric water vapor, this study developed a new, robust operational PWV retrieval algorithm for FY-2 F to improve the operational precision of the current PWV product. The algorithm uses a modified three-band PSW method, which adds a scale for the water vapor channel in the improved three-band PSW method. Integrated PWV products from the radiosonde data in 2016 are used here to validate the precision of the PWV retrieved by the modified three-band and traditional two-band PSW methods. The mean bias, root mean square error(RMSE), and correlation coefficient of the PWV retrieved by the modified three-band PSW method are 0.28 mm, 4.53 mm, and 0.969, respectively. The accuracy is much better than the PWV retrieved by the two-band method, whose mean bias, RMSE, and correlation coefficient are 12.67 mm, 29.35 mm, and 0.23. Especially, in mid-or high-latitude regions, the RMSE of the PWV is improved from 10 to 2 mm by changing the inversion in the two-band method to the modified three-band PSW method. Furthermore, the modified three-band PSW results show a better consistency with the radiosonde PWV at any zonal belt and season than the two-band PSW results. This new algorithm could significantly improve the quality of the current FY-2 F/VISSR PWV product, especially at sites where the actual PWV are lower than 15 mm.  相似文献   

基于短波红外技术的蚀变矿物特征及勘查模型——以斯弄多银铅锌矿床为例   总被引：4，自引：1，他引：3  

郭娜  刘栋  唐菊兴  郑龙  黄一入  史维鑫  伏媛  唐楠  王成 《矿床地质》2018,37(3):556-570

印度-亚洲大陆的碰撞成就了青藏高原的冈底斯成矿带,位于该成矿带的斯弄多银铅锌矿床赋存于林子宗群火山岩中,经过勘查确认该矿床属于低硫化浅成低温热液型矿床。通过对5个钻孔进行短波红外测量,发现钻孔中的蚀变矿物主要有绢(白)云母、钠云母(富Na云母)、伊利石和蒙脱石,并在垂向形成绢(白)云母→绢(白)云母+钠云母+蒙脱石+伊利石→绢(白)云母+伊利石→绢(白)云母的组合特征。通过总结归纳蚀变矿物分布、分带特征并与地质编录相结合,构建了基于短波红外技术的斯弄多找矿勘查模型。笔者在数据分析与模型构建中发现:(1)伊利石-蒙脱石混合矿物组成是寻找深部及外围矿体的重要线索;(2)绢(白)云母属于成矿前期的蚀变,与矿体之间的关系不明显;(3)矿床深部表现为两种不同的化学反应:SW方向深部反映了绢云母被交代形成伊利石的过程;NE方向深部表现为绢(白)云母二八面体结构的变化;(4)未被剥蚀的青磐岩化带是寻找浅成低温热液型金矿的主要依据。  相似文献   

以门源M6.9地震为契机的祁连带中东段地震热红外异常区域特征研究          下载免费PDF全文

张丽峰  张璇  郭瑛霞  胡维云  孙玺皓 《地震工程学报》2022,44(2):398-407,424

以中国静止气象卫星亮温资料为数据基础,使用小波变换和功率谱估计法研究2022年1月8日门源M6.9地震前的热辐射异常,并对祁连带中东段以往震例的热辐射异常作回溯性研究。门源6.9级地震的热辐射异常发展过程可分为3个阶段：初始演化阶段、增强持续阶段、减弱消失阶段。面积最大时强辐射区的面积约为8万km~2,地震发生在其西北部。相对功率谱峰值为平均值的17倍,地震发生在峰值后82天。大面积、高强度的热辐射状态持续时间长是此次异常的显著特点。祁连带中东段的几次地震前均出现过热辐射异常,其特征可为该区震情判定不断积累经验,以期形成可作为判定指标的区域震例库。  相似文献   

赣东北地区矽卡岩典型矿物形成与演化的光谱证据:以朱溪钨多金属矿为例SCIEI北大核心CSCD     

郭娜  王先广  胡正华  刘新星  龙沱江  袁珊  连敦梅  魏德贤 《岩石学报》2022,38(4):1219-1236

朱溪是近年来在江西塔前-赋春成矿带发现的一个世界级超大型钨铜矿床。本文采用短波红外+热红外光谱技术对矿区13个钻孔进行了光谱测量,结合岩石-矿物地球化学分析,探讨了朱溪矿床矽卡岩中典型蚀变矿物的形成与演化过程,厘定了矽卡岩形成不同阶段矿物组合的光谱特征,构建了朱溪矿床的短波红外+热红外光谱勘查模型。研究发现:(1)区内不同矿物组合形成了明显的蚀变分带,由内向外依次为绢云母(富Si)+长石(岩体顶层蚀变,多期流体叠加综合作用)→外矽卡岩:钙铝榴石+透辉石+(绢云母)→透辉石+蛇纹石+绿泥(帘)石+滑石→绢云母(富Al)+绿泥(帘)石(基底不整合面蚀变);(2)Al-OH波长的移动可指示成矿流体压力、温度及pH值的变化;(3)研究区透辉石的形成、演化与矿体之间关系密切,虽然富矿体赋存于矽卡岩形成早期的透辉石-石榴子石蚀变带,但大量矿体则赋存于矽卡岩退蚀变阶段的蛇纹石-绿泥石蚀变带;(4)矿体的形成与流体的混合作用关系极大,伊利石光谱吸收特征能够指示外部冷水(大气降水或地下水)的灌入轨迹。  相似文献