水面菲涅尔反射对~761 nm叶绿素荧光估算的影响     

温颜沙  邓建明  毛志华  石静  周杨  鲁婷  陆应诚 《遥感学报》2018,22(3):424-431

叶绿素荧光是光合作用的有效探针,可用于海洋浮游植物的监测与定量评估。太阳诱导叶绿素荧光覆盖可见光—近红外650—800 nm,在～685 nm与～740 nm表现出两个形态不同的荧光峰特征。基于～685 nm荧光峰的叶绿素浓度反演算法较为成熟,但在高悬浮物和高叶绿素浓度的水体中,算法的有效性不足。基于叶绿素荧光在氧气吸收谱段(O2-A)的填充作用,水体遥感反射率光谱～761 nm峰值中包含有太阳诱导叶绿素荧光信号,能用于水体叶绿素浓度的估算,但该反射峰形态特征还取决于传感器的光谱分辨率。本研究基于不同光谱分辨率的大气吸收谱线特征,模拟了水体遥感反射率光谱(750—775 nm)上太阳诱导叶绿素荧光的信号响应特征;分析了利用遥感反射率(～761 nm)计算叶绿素荧光的原理,阐明了不同光谱分辨率条件下水体叶绿素荧光信号在反射光谱上的形态变化规律。采用水面以上测量法获取的离水光谱辐亮度,包含了水面的菲涅尔反射信号,由于真实的菲涅尔系数难以准确测量,这给基于～761 nm处遥感反射率峰值的荧光信号估算带来不确定性影响。研究表明,假定菲涅尔系数为0时,虽然～761 nm叶绿素荧光信号与其浓度具有较好的线性统计关系,但却带来较大的不确定性;这种不确定的影响,在低浓度叶绿素水体中表现明显,在高浓度叶绿素水体中,影响相对较小;准确估算菲涅尔系数,有助于减少这种不确定性影响。对基于遥感反射率～761 nm叶绿素荧光信号的深入探讨,将能推动未来水体叶绿素荧光的识别与利用。  相似文献   

高光谱遥感影像混合像元分解研究进展   总被引：6，自引：1，他引：5  

蓝金辉  邹金霖  郝彦爽  曾溢良  张玉珍  董铭巍 《遥感学报》2018,22(1):13-27

受高光谱成像仪低空间分辨率及复杂地物的影响,高光谱遥感图像存在大量混合像元。为提高地表分类精度以及满足亚像元级目标探测的需求,混合像元分解技术一直是高光谱遥感研究热点之一。本文主要对高光谱混合像元分解技术中的核心问题:端元数目估计、端元提取算法、丰度估计算法进行综述,系统地分析了各种典型算法的原理及优缺点,进一步阐述研究过程中建立高精度遥感混合反演模型与遥感产品业务化中的混合像元分解技术难题,同时针对今后混合像元分解技术发展方向,指出在继续引入新型算法理论方法基础上,结合用户应用需求,推进高光谱混合像元分解算法业务化应用,为高光谱遥感工程化应用提供支持。  相似文献   

Mapping fractional landscape soils and vegetation components from Hyperion satellite imagery using an unsupervised machine-learning workflow     

Michael J. Friedel  Massimo Buscema  Luiz Eduardo Vicente  Fabio Iwashita  Andréa Koga-Vicente 《International Journal of Digital Earth》2018,11(7):670-690

An unsupervised machine-learning workflow is proposed for estimating fractional landscape soils and vegetation components from remotely sensed hyperspectral imagery. The workflow is applied to EO-1 Hyperion satellite imagery collected near Ibirací, Minas Gerais, Brazil. The proposed workflow includes subset feature selection, learning, and estimation algorithms. Network training with landscape feature class realizations provide a hypersurface from which to estimate mixtures of soil (e.g. 0.5 exceedance for pixels: 75% clay-rich Nitisols, 15% iron-rich Latosols, and 1% quartz-rich Arenosols) and vegetation (e.g. 0.5 exceedance for pixels: 4% Aspen-like trees, 7% Blackberry-like trees, 0% live grass, and 2% dead grass). The process correctly maps forests and iron-rich Latosols as being coincident with existing drainages, and correctly classifies the clay-rich Nitisols and grasses on the intervening hills. These classifications are independently corroborated visually (Google Earth) and quantitatively (random soil samples and crossplots of field spectra). Some mapping challenges are the underestimation of forest fractions and overestimation of soil fractions where steep valley shadows exist, and the under representation of classified grass in some dry areas of the Hyperion image. These preliminary results provide impetus for future hyperspectral studies involving airborne and satellite sensors with higher signal-to-noise and smaller footprints.  相似文献   

Assessing soil salinity using WorldView-2 multispectral images in Timpaki,Crete, Greece   总被引：2，自引：0，他引：2  

D. D. Alexakis  I. N. Daliakopoulos  I. S. Panagea  I. K. Tsanis 《国际地球制图》2018,33(4):321-338

Salinization is one of the major soil degradation threats occurring worldwide. This study evaluates the feasibility of operational surface soil salinity mapping based on state-of-the-art Earth Observation (EO) products captured by sensors on-board WorldView-2 (WV2) and Landsat 8 satellites. The proposed methods are tested in Timpaki, south-central Crete,Greece, where brackish water irrigation puts soil health at risk of soil salinization. In all cases, EO products are calibrated against soil samples collected from bare soil locations. Results indicate a moderate correlation of observed EC_e values with the investigated remote sensing parameters. Regarding sensitivity to saline soil, the yellow band displays higher values. Comparison between methods used in the literature shows that those developed specifically for soil salinity, and especially index S5, perform better. The proposed ‘detection index’ and 3D PCA transformation methodology perform reasonably well in detecting areas with high EC_e values and provide a simple and effective operational alternative for saline topsoil detection and mapping.  相似文献   

Fuel type mapping using object-based image analysis of DMC and Landsat-8 OLI imagery     

A. Stefanidou  E. Dragozi  D. Stavrakoudis  I. Z. Gitas 《国际地球制图》2018,33(10):1064-1083

Efficient forest fire management requires precise and up-to-date knowledge regarding the composition and spatial distribution of forest fuels at various spatial and temporal scales. Fuel-type maps are essential for effective fire prevention strategies planning, as well as the alleviation of the environmental impacts of potential wildfire events. The aim of this study was to assess and compare the potential of Disaster Monitoring Constellation and Landsat-8 OLI satellite images (Operational Land Imager), combined with Object-Based Image Analysis (GEOBIA), in operational mapping of the Mediterranean fuel types at a regional scale. The results showcase that although the images of both sensors can be used with GEOBIA analysis for the generation of accurate fuel-type maps, only the OLI images can be considered as applicable for regional mapping of the Mediterranean fuel types on an operational basis.  相似文献   

Quantifying land use/land cover spatio-temporal landscape pattern dynamics from Hyperion using SVMs classifier and FRAGSTATS®     

Salim Lamine  Sudhir Kumar Singh  Szilárd Szabó  Nour El Islam Bachari  Prashant K. Srivastava 《国际地球制图》2018,33(8):862-878

This study aims to quantify the landscape spatio-temporal dynamics including Land Use/Land Cover (LULC) changes occurred in a typical Mediterranean ecosystem of high ecological and cultural significance in central Greece covering a period of 9 years (2001–2009). Herein, we examined the synergistic operation among Hyperion hyperspectral satellite imagery with Support Vector Machines, the FRAGSTATS^® landscape spatial analysis programme and Principal Component Analysis (PCA) for this purpose. The change analysis showed that notable changes reported in the experimental region during the studied period, particularly for certain LULC classes. The analysis of accuracy indices suggested that all the three classification techniques are performing satisfactorily with overall accuracy of 86.62, 91.67 and 89.26% in years 2001, 2004 and 2009, respectively. Results evidenced the requirement for taking measures to conserve this forest-dominated natural ecosystem from human-induced pressures and/or natural hazards occurred in the area. To our knowledge, this is the first study of its kind, demonstrating the Hyperion capability in quantifying LULC changes with landscape metrics using FRAGSTATS^® programme and PCA for understanding the land surface fragmentation characteristics and their changes. The suggested approach is robust and flexible enough to be expanded further to other regions. Findings of this research can be of special importance in the context of the launch of spaceborne hyperspectral sensors that are already planned to be placed in orbit as the NASA’s HyspIRI sensor and EnMAP.  相似文献   

Remote sensing for wetland classification: a comprehensive review     

Sahel Mahdavi  Bahram Salehi  Jean Granger  Meisam Amani  Brian Brisco  Weimin Huang 《地理信息系统科学与遥感》2018,55(5):623-658

  相似文献   

Region of interest extraction via common salient feature analysis and feedback reinforcement strategy for remote sensing images     

Libao Zhang  Qiaoyue Sun  Jue Zhang 《地理信息系统科学与遥感》2018,55(5):745-762

Saliency detection is an effective approach to extract regions of interest (ROIs) for remote sensing images. However, existing saliency detection models mainly focus on ROI extraction from a single image and usually are not able to produce satisfactory results because of complex background interference in remote sensing images. The employment of mutual information in a set of remote sensing images can provide an effective solution to this issue. In this paper, we propose a novel saliency detection model for multiple remote sensing images to simultaneously extract ROIs and identify images without ROIs. First, common salient feature analysis based on synthesized feature clustering and global contrast is implemented to exploit global correspondence in the synthesis feature domain, thereby highlighting preliminary ROIs against background interference and assigning lower saliency values to images without ROIs. Then, we design an exclusion criterion based on saliency value judgment to remove images without ROIs, and the remaining saliency maps are refined by an enhancement strategy. Finally, the enhanced maps serve as a feedback to yield a homogenous synthesized feature space in which integral ROIs with subtle borders are extracted by the reused cluster-based saliency calculation. Experiments reveal that our model outperforms seven state-of-the-art models by achieving the best ROC curve (AUC = 0.945) and maximal F-measure at 0.729.  相似文献   

Examining human heat stress with remote sensing technology     

Yang Song 《地理信息系统科学与遥感》2018,55(1):19-37

Heat stress as an environmental hazard which can seriously affect productivity, health, or even survival of individuals has long been studied. Despite the endeavors that have been made to address the issue quantitatively with various heat stress indices, they are often measured at scatter sites. This research devotes to revealing human heat stress within continuous space with remote sensing technology. The study began with the retrieval of dry-bulb temperature from land surface temperature (LST) with empirical models. As wet-bulb temperature was calculated from dry-bulb temperature and relative humidity, discomfort index (DI) as an indicator of heat stress was revealed for the study area at 1 km spatial resolution for three summer days. Results indicated that DI can be derived within continuous space with remotely sensed data, and its spatial distribution can be dramatically affected by relative humidity. Further comparison between DI and LST indicated that LST as a widely utilized indicator of surface thermal condition fails to address human heat stress as environmental factors such as relative humidity are not taken into account.  相似文献   

基于卫星遥感的洞庭湖水体面积变化及与水文的相关性          下载免费PDF全文

黄菊梅  韩沁哲  姚晟  蒋帅  黄海波 《中低纬山地气象》2022,46(1):27-31

该文利用2006-2020年洞庭湖水体遥感面积及水文资料,对洞庭湖水体面积变化特征及其与水文的相关性进行了探讨。结果表明洞庭湖水体面积离散程度较高且变幅大。岳阳市、益阳市、常德市水体面积分别占洞庭湖水体面积的68.62%、25.77%、5.61%。其中位于岳阳市的岳阳县、湘阴县、位于益阳市的沅江市水体面积分别占洞庭湖水体面积的34.89%、17.35%、23.52%。占比越大的县市水体面积与洞庭湖水体面积相关性越大。洞庭湖水体面积与城陵矶水位的相关性高于常德、益阳水位。2010-2020年洞庭湖水体年最大面积显著增大。洞庭湖水体面积与城陵矶水位4阶多项式曲线拟合相关性最优。此外,不同的卫星/仪器、算法、分辨率以及天气条件对洞庭湖水体面积会产生一定的影响,洞庭湖区强降水对洞庭湖水体面积影响较大。  相似文献