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1.
Change detection is a standard tool to extract and analyze the earth's surface features from remotely sensed data. Among the different change detection techniques, change vector analysis(CVA) have an exceptional advantage of discriminating change in terms of change magnitude and vector direction from multispectral bands. The estimation of precise threshold is one of the most crucial task in CVA to separate the change pixels from unchanged pixels because overall assessment of change detection method is highly dependent on selected threshold value. In recent years, integration of fuzzy clustering and remotely sensed data have become appropriate and realistic choice for change detection applications. The novelty of the proposed model lies within use of fuzzy maximum likelihood classification(FMLC) as fuzzy clustering in CVA. The FMLC based CVA is implemented using diverse threshold determination algorithms such as double-window flexible pace search(DFPS), interactive trial and error(TE), and 3×3-pixel kernel window(PKW). Unlike existing CVA techniques, addition of fuzzy clustering in CVA permits each pixel to have multiple class categories and offers ease in threshold determination process. In present work, the comparative analysis has highlighted the performance of FMLC based CVA overimproved SCVA both in terms of accuracy assessment and operational complexity. Among all the examined threshold searching algorithms, FMLC based CVA using DFPS algorithm is found to be the most efficient method.  相似文献   

2.
1 Introduction With the rapid development of remotely sensed (RS) information collection, transfer and storage in the last two decades, the limitation of RS application is becom- ing weaker because of availability of multiple RS data sources of increasingly finer spatial, temporal, spectral and radiant dimensions. In the high spatial-resolution RS imagery, characteristics of land-cover are fairly clear such as spatial shape, structure, texture, etc., so the mixture of different land covers …  相似文献   

3.
在遥感图像网络化分布式特征分析与表达过程中,有很多需要栅格数据与矢量数据的混合模型的网络化表达与传输问题,而矢量数据的网络化表达、传输与显示问题则是影响遥感图像分布式处理效率的关键性因素之一。本文首先对SVG技术及其对矢量数据的表达特点作了简介,在介绍遥感图像分布式特征提取系统的运行流程的基础上,对其在遥感图像分布式处理中相关的网络化数据表达与显示问题给出了相应的解决思路,并给出了相应的实例与效果分析。  相似文献   

4.
采用分坡度、分NDVI（归一化差异植被指数）和分地类的C校正策略,对复杂地形山区Landsat TM影像进行地形校正,并运用视觉检验、回归分析和遥感分类精度将3种C校正策略的结果与传统的整体C校正进行对比,以探寻适合复杂地形山区的C校正策略。在此基础上,进一步探讨了地形校正对影像重采样尺度的响应。研究结果表明：与传统的整体C校正相比,采用分坡度、分NDVI和分地类的C校正策略能更好地消除原影像的凹凸感,减弱地形效应,且背阳面影像的过校正现象减少;各种C校正策略和整体C校正对Landsat TM影像不同波段的校正效果不一,其中,分地类的C校正策略对波段1、2、3和波段7的校正效果最好,分坡度的C校正策略对波段5的校正效果更佳,而整体C校正则对波段4的校正效果最好;虽然所有C校正均能有效地消除影像中的地形效应,但并未能提高影像分类精度;从不同重采样尺度C校正结果对比看,随着采样尺度增加,地形效应逐渐减弱,但并未完全消除,因此,中、低空间分辨率遥感影像的地形效应也不容忽视。  相似文献   

5.
The downward shortwave radiation(DSR) is an essential parameter of land surface radiation budget and many land surface models that characterize hydrological,ecological and biogeochemical processes.The new Global LAnd Surface Satellite(GLASS) DSR datasets have been generated recently using multiple satellite data in China.This study investigates the performances of direct comparison approach,which is mostly used for validation of surface insolation retrieved from satellite data over the plain area,and indirect comparison approach,which needs a fine resolution map of DSR as reference,for validation of GLASS DSR product in time-steps of 1 and 3 hours over three Chinese Ecosystem Research Network sites located in the rugged surface.Results suggest that it probably has a large uncertainty to assess GLASS DSR product using the direct comparison method between GLASS surface insolation and field measurements over complex terrain,especially at Mt.Gongga 3,000 m station with root mean square error of 279.04 and 229.06 W/m2in time-steps of 1 and 3 hours,respectively.Further improvement for validation of GLASS DSR product in the rugged surface is suggested by generation of a fine resolution map of surface insolation and comparison of the aggregated fine resolution map with GLASS product in the rugged surface.The validation experience demonstrates that the GLASS DSR algorithm is satisfactory with determination coefficient of 0.83 and root mean square error of 81.91W/m2over three Chinese Ecosystem Research Network sites,although GLASS product overestimates DSR compared to the aggregated fine resolution map of surface insolation.  相似文献   

6.
生态环境遥感分类数据矢量化方法与应用   总被引：4，自引：2，他引：2  
遥感分类数据矢量化建库是生态环境遥感制图及其应用分析过程中主要的处理内容和基础工作。以福建省海岸带生态环境遥感分类数据为例 ,在分析遥感图像处理系统对遥感分类和专题信息提取后处理中矢量化能力不足和结果存在严重缺陷的基础上 ,综合应用遥感和地理信息基础软件平台 ,提供的系列数据管理、分析和数据转换功能模块 ,开展基于生态环境遥感影像分类数据的矢量化建库技术探讨 ,提出一个生态环境遥感分类数据矢量化建库的通用技术方法和流程 ,并对矢量化结果做了一个简要的评价和分析 ,以满足大面积生态环境遥感调查、分析和制图的实际需要。  相似文献   

7.
建筑物是城市地理数据库中最容易发生变化和最需要更新的部分,其更新工作量巨大,因此开展对高分辨率遥感影像中的建筑物进行自动提取和变化检测研究具有重要的意义.本文以精确提取变化建筑物的位置和轮廓为目标,基于图分割提出一种高分辨率遥感影像建筑物变化检测方法.首先,将遥感影像中的每个像元映射成图的顶点,利用像元之间的距离阈值构造图的边,综合利用位置,灰度和边缘3种特征计算边的权值,将遥感影像的分割转化为图的分割,并用归一化图分割方法得到分割对象集合;然后,以长宽比和矩形度作为约束条件,对2期遥感影像中的分割对象集合进行筛选,提取建筑物对象;最后,根据2期影像中建筑物之间的空间,面积和格局关系识别建筑物的变化类型(包括新增,消失和改建),并对其进行可视化表达.为了验证本文方法的有效性,分别以深圳市的WorldView影像和北京市的QuickBird全色影像为数据源,从中选取13组具有代表性的子影像进行实验.结果表明,本文提出的方法对配准精度较低的影像组具有一定的适应性,容许的配准误差达到20个像元(10 m),平均查准率和平均查全率分别达到93.16%和87.90%.  相似文献   

8.
尺度转换是遥感信息科学领域的研究热点,其传统研究方法大多局限于统计模型,对数据的空间结构信息考虑较少,很难满足遥感数据的多尺度表达要求。基于此,针对遥感数据的尺度不一致问题,本文提出了一种利用高斯金字塔的图像模糊特性进行遥感数据尺度上推的方法,在对金字塔每一层的数据高斯模糊的基础上,通过多次连续的降采样,得到一系列不同尺度的数据,从而满足实际应用的空间分辨率要求。为了验证本文所提方法的有效性,本文选择Landsat7 ETM影像和ASTER GDEM为研究数据进行尺度上推,并与传统的最邻近、双线性以及立方卷积等方法进行了实验对比,采用均值、方差、均方根误差、平均绝对误差等评价指标,以及相同分辨率的ASTER GDEM和SRTM DEM的等高线套合结果来衡量高斯金字塔方法的性能。实验结果表明,本文使用的高斯金字塔尺度上推方法能够有效地实现连续遥感数据的尺度转换,在保持遥感数据局部细节特征的基础上,较好地保持了原始遥感数据的信息量以及空间结构特征。  相似文献   

9.
Land surface hydrothermal conditions(LSHCs) reflect land surface moisture and heat conditions, and play an important role in energy and water cycles in soil-plant-atmosphere continuum. Based on comparison of four evaluation methods(namely, the classic statistical method, geostatistical method, information theory method, and fractal method), this study proposed a new scheme for evaluating the spatial heterogeneity of LSHCs. This scheme incorporates diverse remotely sensed surface parameters, e.g., leaf area index-LAI, the normalized difference vegetation index-NDVI, net radiation-Rn, and land surface temperature-LST. The LSHCs can be classified into three categories, namely homogeneous, moderately heterogeneous and highly heterogeneous based on the remotely sensed LAI data with a 30 m spatial resolution and the combination of normalized information entropy(S') and coefficient of variation(CV). Based on the evaluation scheme, the spatial heterogeneity of land surface hydrothermal conditions at six typical flux observation stations in the Heihe River Basin during the vegetation growing season were evaluated. The evaluation results were consistent with the land surface type characteristics exhibited by Google Earth imagery and spatial heterogeneity assessed by high resolution remote sensing evapotranspiration data. Impact factors such as precipitation and irrigation events, spatial resolutions of remote sensing data, heterogeneity in the vertical direction, topography and sparse vegetation could also affect the evaluation results. For instance, short-term changes(precipitation and irrigation events) in the spatial heterogeneity of LSHCs can be diagnosed by energy factors, while long-term changes can be indicated by vegetation factors. The spatial heterogeneity of LSHCs decreases when decreasing the spatial resolution of remote sensing data. The proposed evaluation scheme would be useful for the quantification of spatial heterogeneity of LSHCs over flux observation stations toward the global scale, and also contribute to the improvement of the accuracy of estimation and validation for remotely sensed(or model simulated) evapotranspiration.  相似文献   

10.
In this study,we used remotely sensed data,GIS modeling,and statistical methods to evaluate the damage caused by the Wenchuan Earthquake (May 12,2008) to the giant panda (Ailuropoda melanoleuca) habitat in the World Nature Heritage Sichuan Giant Panda Sanctuary (WHSGPS) in China.A landscape ecological analysis found increases of landscape heterogeneity,complexity,and fragmentation in the giant panda habitat after the earthquake.A terrain analysis found that slope and elevation are directly associated with t...  相似文献   

11.
This paper firstly investigated the land-use and land-cover change (LUCC) in the Hun-Taizi River watershed, Northeast China from 1988 to 2004 based on remotely sensed images and geographic information systems (GIS) technology. Then, using the famous land-use change model of Conversion of Land Use and its Effects at Small regional extent (CLUE-S), this paper simulated the land use changes under historical trend (HT), urban planning (UP) and ecological protection (EP) scenarios considering urban planning and ...  相似文献   

12.
多源地学信息综合处理包括复合(Integration,拟合)和叠合(Overlay,叠加)两种处理形式。地理信息系统为多源地学信息综合处理提供技术支持和保证。多源地学信息范围很广,从大的方面来说,包括地质、地理、地球物理、地球化学、遥感等各种地面、空中调查和探测的数据。本文基于地理信息系统,以松辽盆地西部斜坡为例,来探讨地球物理与遥感信息的相关性,然后对其进行复合和叠合处理。  相似文献   

13.
利用DEM分析方法为起伏地形下太阳辐射模拟提供了条件。然而DEM的尺度效应对太阳辐射模拟产生很大的影响。本文以黄土丘陵和秦岭高山为实验样区,以一系列不同分辨率的DEM,模拟日、月及年总天文辐射,比较其误差大小及地形分析的差异。实验结果显示,随着DEM栅格分辨率的降低,天文辐射逐渐增大;当栅格分辨率大于地面相对高差时,模拟的天文辐射基本稳定,坡向、坡度等地形因子对辐射的再分配作用已不显著。黄土丘陵区,当DEM分辨率接近1000m时,天文辐射年总量的相对误差为22%,超过该区域一个冬季的天文辐射量。秦岭山区地表起伏大,误差较黄土丘陵地区小,最大相对误差为17.8%。总之,地表起伏越小,DEM栅格分辨率对太阳辐射模拟的影响越大。  相似文献   

14.
地形校正是崎岖山区遥感图像预处理的关键步骤。为了评估基于DEM数据的经验校正模型、山地辐射传输模型和波段组合优化计算模型在去除地形阴影效应方面的性能,并将其应用于福州市植被覆盖监测,本文采用C模型（和SCS+C模型）、6S+C模型和阴影消除植被指数（SEVI）进行评估、比较。采用1999年和2014年两期Landsat 5 TM卫星数据和相关的 30 m ASTER GDEM V2高程数据,分别计算了C校正（和SCS+C校正）和6S+C校正后的归一化植被指数（NDVI）和比值植被指数（RVI）以及基于表观反射率数据的SEVI。通过目视比较、光谱特征比较以及太阳入射角余弦值（cos i）与植被指数的线性回归分析,可以看出C模型和SCS+C模型对本影具有较好的校正效果,但对落影的校正效果欠佳。NDVI和RVI的本影与邻近无阴影阳坡的相对误差分别从71.64%、52.57%降至4.80%、6.43%（C模型）和0.50%、9.94%（SCS + C模型）,而落影与邻近无阴影阳坡的相对误差分别从62.01%、47.57%降至31.05%、24.40%（C模型）和33.42%、16.01%（SCS + C模型）。在NDVI的落影校正效果上,6S+C模型比C模型和SCS+C模型有一定的提升,本影与邻近无阴影阳坡之间的相对误差为8.63%,落影与邻近无阴影阳坡之间的相对误差为14.27%。而SEVI在消除本影和落影方面整体效果更好,本影和落影与邻近无阴影阳坡的相对误差分别为9.86%和10.53%。最后,基于SEVI对福州市1999-2014年的植被覆盖变化进行了监测。监测结果表明： ① 1999-2014年植被覆盖增加了893.61 km 2,植被增加区域主要分布在海拔250~1250 m范围内;② SEVI均值在坡度40°附近达到峰值。  相似文献   

15.
The Himalaya harbor rich floristic diversity which is of immense scientific interest and socio-economic importance.In this study, floristic diversity of a remote alpine valley has been studied based on information extracted from remotely sensed satellite data along with field surveys undertaken during 2008-2014.Analysis of vegetation information from satellite data revealed that ~75% of the area is covered with natural vegetation which comprises lush green coniferous forests, alpine pastures and alpine scrub lands.With inputs from vegetation information extracted from satellite data, comprehensive field surveys were planned to document the floristic diversity of the region.Analysis of species composition showed a total of 285 plant species,belonging to 191 genera in 60 families.Of these, 250 species are herbs, 14 shrubs, 2 sub-shrubs and 19 trees.The dicotyledons are represented by 240 species, monocotyledons 30, gymnosperms 04, andpteriodophytes 11 species.Asteraceae is the largest family with 35 species.During the present study, 5species(Corydalis cashmeriana, Hippophae rhamnoides, Primula minutissima, Saussurea sacra and Inula orientalis) have been recorded for the first time from this Himalayan region.The study demonstrates the benefits of geo-informatics in floristic studies, particularly the robustness of remotely sensed data in identifying areas with potentially high species richness, which would be otherwise difficult in a complex mountainous terrain using traditional floristic surveys alone.The present study is expected to provide baseline scientific data for cutting edge studies relating to long term ecological research, bioprospecting, possible impacts of changing climate on vegetation and sustainable use of plant resources in this Himalayan region.  相似文献   

16.
夜光遥感大数据视角下的中国城市化时空特征   总被引：1，自引：0，他引：1  
社会经济的高速发展直接驱动了中国过去几十年的持续快速城市化进程。城市化是一个典型的复杂地理现象,伴随着高密度人口聚集、土地利用改变、基础设施建设和生态环境变化等系列人和自然交互过程的发生。深入理解城市发展的时空演化规律对研究、规划、管理和相关政策制定在内的诸多领域都有十分重要的意义。近些年来,由于快速发展的夜光遥感大数据具有空间清晰的与城市化有关的社会经济活动强度的感知信息,其为探索城市和城市化问题提供了新的研究途径。虽然有许多成果对利用夜光遥感数据进行城市化的研究进行了探讨,但大部分集中在城市化面积、人口规模和其他社会经济变量的定量相关和数值统计分析上,仍然缺乏对中国过去几十年来的城市化时空特征的综合多角度分析和理解。本研究利用1992-2013年的夜光遥感时间序列大数据,从夜光照亮面积、亮度变化时间转折点、不同亮度区的空间结构转换和亮度信号的空间扩散速度4个方面进行了定量化的信息提取与分析。研究结果从夜光辐射遥感大数据的视角综合揭示了中国在过去研究期间包括城市空间扩展、城市化发展的时间分布、城市空间结构演化和城市化活动空间扩散速度在内的定量时空特征。本研究的结果可以为深入理解中国城市化的时空模式与演化特征提供新的参考。  相似文献   

17.
The visible and infrared bands of Landsat Thematic Mapper (TM) can be used for inland water studies. A method of retrieving water-leaving radiance from TM image over Taihu Lake in Jiangsu Province of China was investigated in this article. To estimate water-leaving radiance, atmospheric correction was performed in three visible bands of 485nm, 560nm and 660nm. Rayleigh scattering was computed precisely, and the aerosol contribution was estimated by adopting the clear-water-pixels approach. The clear waters were identified by using the Landsat TM middle-infrared band (2.1μm), and the water-leaving radiance of clear water pixels in the green band was estimated by using field data. Aerosol scattering at green band was derived for six points, and interpolated to match the TM image. Assuming the atmospheric correction coefficient was 1.0, the aerosol scattering image at blue and red bands were derived. Based on a simplified atmospheric radiation transfer model, the water-leaving radiance for three visible bands was retrieved. The water-leaving radiance was normalized to make it comparable with that estimated from other remotely sensed data acquired at different times, and under different atmospheric conditions. Additionally, remotely sensed reflectance of water was computed. To evaluate the atmospheric correction method presented in this article, the correlation was analyzed between the corrected remotely sensed data and the measured water parameters based on the retrieval model. The results show that the atmospheric correction method based on the image itself is more effective for the retrieval of water parameters from Landsat TM data than 6S (Second Simulation of the Satellite Signal in the Solar Spectrum) code based on standard atmospheric and aerosol models.  相似文献   

18.
基于Google Earth Engine的红树林年际变化监测研究   总被引：1，自引：0，他引：1  
遥感技术已广泛应用于红树林资源调查与动态监测中,但仍然存在遥感数据获取困难、数据预处理工作量大、监测时间长而周期过大等问题,影响了学者对红树林演变过程的精细刻画与理解。本文基于Google Earth Engine（GEE）云遥感数据处理平台,选取Landsat系列卫星数据,生成长时间序列年际极少云影像集（云量少于5%）,利用3个红外波段反射率（NIR、SWIR1、SWIR2）和3个特征指数（NDVI、NDWI、NDMI）建立阈值规则集,实现对实验区越南玉显县红树林、红树林-虾塘、不透水面-裸地、水体4种目标地物的专家知识决策树分类和土地覆盖的制图,并基于分类结果监测该区域1993-2017年的红树林年际动态变化。结果表明：GEE平台可满足多云多雨地区红树林的长时间序列年际变化监测需求;本文阈值分类方法可以有效提取红树林及红树林-虾塘,实验区有86%年份的影像分类精度达到80%以上;年际变化监测可精细刻画实验区红树林面积先增后减再增的变化过程,也能准确反映红树林与红树林-虾塘养殖系统面积之间的负相关关系。红树林年际动态监测结果可以降低红树林演变分析的不确定性,并能更精细地量化红树林与其他土地覆盖类型的转化过程,从而评估经济发展、政策等因素对红树林演变的影响。  相似文献   

19.
地形纹理是区分不同地貌形态的重要依据,DEM是地形纹理分析的重要数据。然而,DEM分辨率使地形纹理特征提取存在着不确定性问题。本文以具有显著地貌多样性与差异性的陕西省为例,选择6个不同地貌类型区为研究区,以25 m分辨率DEM数据作为信息源,构建了多尺度的地面坡度、光照模拟和粗糙度数据序列。在此基础上,引入空间灰度共生矩阵（GLCM）对地形表面纹理特征进行量化分析,以揭示数据分辨率对地形纹理特征提取的影响。研究表明：对于单一样区,在DEM及其3个派生数据中,原始高程数据和粗糙度数据的纹理参数特征值,对分辨率的变化较为敏感。对于不同的地貌类型区,二阶角矩和对比度这2个纹理参数具有最大的变异系数,表明它们对于区分不同地貌类型的能力最强;二阶角矩具有较大的尺度依赖性,随着分辨率的降低,其区分能力急剧降低,而对比度对于地貌的区分能力,则随着分辨率的降低而增强,并保持在一个较大的范围内。DEM数据的对比度对于不同地貌的区分能力,在所选4个参数中最为稳定,而粗糙度数据的二阶角矩区分不同地貌的能力,随着数据分辨率的变化而最不稳定。以上结果对于根据不同的研究对象选择适宜的DEM分辨率及地形纹理参数具有一定的指导意义。  相似文献   

20.
Shadow is one of the major problems in remotely sensed imagery which hampers the accuracy of information extraction and change detection.In these images,shadow is generally produced by different objects,namely,cloud,mountain and urban materials.The shadow correction process consists of two steps:detection and de-shadowing.This paper reviews a range of techniques for both steps,focusing on urban regions(urban shadows),mountainous areas(topographic shadow),cloud shadows and composite shadows.Several issues including the problems and the advantages of those algorithms are discussed.In recent years,thresholding and recovery techniques have become important for shadow detection and de-shadowing,respectively.Research on shadow correction is still an important topic,particularly for urban regions(in high spatial resolution data) and mountainous forest(in high and medium spatial resolution data).Moreover,new algorithms are needed for shadow correction,especially given the advent of new satellite images.  相似文献   

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