共查询到20条相似文献，搜索用时 109 毫秒
1.
ASTER影像提取植被信息的NDVI与SAVI法比较——以广州花都区为例 总被引：3，自引：1，他引：2
基于ASTER遥感影像,使用IDL语言编写归一化差异植被指数(NDVI)和土壤调整植被指数(SAVI)的计算公式,对遥感影像进行处理,分别对两种方法处理后的遥感影像采用K-Means分类,经过分类后处理,提取植被信息.NDVI整体上较好地反映了不同土地覆被信息;而SAVI对于各种地类的值域较宽,反映绿色植被内部差异信息较明显,可为不同植被类型的信息提取提供方法参考. 相似文献
2.
《云南地理环境研究》2017,(6)
基于不同辐射校正水平的遥感数据,分别利用遥感影像的灰度值(DN)、表观反射率(TOA)与地表反射率(Surface)提取研究区NDVI,采用定量遥感和回归分析方法从空间和时间两个方面对不同辐射水平下提取的NDVI变化特征进行了详细的对比分析,定量评价了大气对于提取的植被指数的影响。结果表明:在空间特征上,根据灰度值、表观反射率与地表反射率提取的NDVI基本都可以用来反映植被信息变化特征,相应的NDVI值呈逐渐增加趋势;根据地表反射率反演的NDVI曲线差异明显。在时间特征上,NDVI整体呈现显著上升的趋势,其中基于地表反射率的NDVI与年际之间线性关系最好,且NDVI最高。 相似文献
3.
基于Whittaker滤波的陕西省植被物候特征 总被引：1，自引：0，他引：1
运用Whittaker滤波重构MODIS NDVI时序数列,利用地理探测器对比滤波前后影像信噪比,采用动态阈值法获取2000-2012年陕西省植被的3个关键物候参数(返青期、枯黄期和生长周期),在此基础上分析了该区植被物候参数空间分布特征。结果表明:(1)Whittaker滤波能够平滑原始NDVI曲线,有效减少原始影像的噪声,提高影像辨识度,并且参数设置简单;(2)陕西省植被物候地区分异明显,不同气候区划类植被物候表现出中温带半干旱区-暖温带半干旱区-暖温带半湿润区-北亚热带湿润区的递变规律:返青期逐步提前,枯黄期逐步推迟;(3)植被物候受高程和纬度影响,并且纬度影响更显著。海拔每升高200 m,返青期推迟1.3 d,枯黄期提前0.6 d;纬度每升高0.5°,返青期推迟3.6 d,枯黄期提前1.2 d。 相似文献
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辐射干燥指数影响下NDVI与气候因子的关系 总被引：4，自引：0，他引：4
在全球1o×1o 分辨率格点数据的基础上研究了1986～1990年多年平均NOAA/AVHRR的归一化植被指数 (NDVI) 与多年平均降水 (Pcp)、多年平均净辐射量 (NetRn)、多年平均辐射干燥指数 (RDI) 之间的关系,结果表明： (1) NDVI与降水、辐射干燥指数总体上存在对数关系,NDVI与净辐射量总体上存在线性关系。 (2) 在不同的辐射干燥指数下,NDVI与降水、净辐射的相关性存在很大的差异。当辐射干燥指数小于1时,NDVI与降水、净辐射之间存在明显的非线性关系;当它大于1且小于2时,NDVI与降水的非线性关系略好于线性关系;当它大于2且小于10时,它们存在明显的线性关系;而当辐射干燥指数大于10时,它们之间的相关性很小。 (3) 以全球13种植被为基础,分别研究了不同植被类型下的NDVI与降水、辐射干燥指数、净辐射量之间的关系,结果表明不同植被类型下的NDVI与这些气候因子的相关性不同,分层聚类的结果表明,这13种植被类型下的NDVI与降水、净辐射的关系可以分为4种类型。 相似文献
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1982~1999 年我国东部暖温带植被 生长季节的时空变化 总被引：23，自引：1，他引：22
利用1982~1996 年5 个站点的植物群落物候观测数据和物候累积频率拟合法, 划分各站逐年的植被物候季节, 并确定各季节初日对应的当地归一化差值植被指数(NDVI) 阈值。 在此基础上, 通过对物候站各年NDVI 曲线的年型聚类分析和区内所有像元逐年NDVI 曲线的空间聚类分析, 实现植被物候季节的时空外推估计, 从而得到我国暖温带落叶阔叶林地区1982~1999 年植被物候季节初日和生长季节长度的时空格局。结果表明, 多年平均的植被物 候季节初日和生长季节长度呈现出主要随纬度和海拔高度变化的空间格局。在这18 年中, 整 个区域的物候春季初日以提前为主, 且以华北平原提前的趋势最为显著;夏季、秋季和冬季 初日以推迟为主, 也以华北平原推迟的趋势比较显著;因此, 华北平原植被生长季节呈显著 延长的趋势。本文揭示的植被物候季节初日的趋势变化与华北地区各季节气温的趋势变化基本吻合;植被生长季节的趋势变化特征与欧洲单种植物物候生长季节, 以及欧亚大陆和我国温带遥感植被生长季节的趋势变化基本一致, 但植被生长季节初、终日期和长度的趋势值明显大于后者, 表明该地区植物物候对于气候变暖的响应更加敏感。 相似文献
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《云南地理环境研究》2016,(2)
2003年来随着普洱市"边三县"(孟连、西盟、澜沧)大面积人工桉树林的引种,该地区植被覆盖发生了较大变化。以桉树引种较多的普洱市"边三县"为研究区、TM影像为数据源,在RS和GIS的支持下,通过计算并处理各期影像NDVI(归一化植被指数)值,并用MODIS数据处理结果进行验证的方法,对三县范围内的植被覆盖时空变化进行分析。结果表明:研究区在2000~2010年植被覆盖情况得到很大改善,2010~2014年整体植被覆盖度有下降的趋势;2000~2014年高植被覆盖区和低植被覆盖区相对不变,各乡镇植被覆盖变化趋势相同。 相似文献
7.
绿洲植被覆盖度遥感信息提取——以敦煌绿洲为例 总被引：1，自引：0，他引：1
以敦煌绿洲为研究区,利用Landsat TM遥感数据,通过归一化植被指数(NDVI)和混合像元分解两种方法,提取了敦煌绿洲的植被覆盖度信息。在基于NDVI提取植被覆盖度时,选取了基于NDVI的像元二分模型; 在混合像元分解过程中,对遥感影像进行波段反射率归一化处理和最小噪声变换(MNF),确定了3个类型端元:植被、不透水表面/土壤、水体/阴影; 最后利用高分辨率遥感影像验证对比了两种提取方法的精度。结果表明:混合像元分解更能准确地提取敦煌地区植被覆盖度信息,其线性相关系数为0.8915,均方根误差为0.0882,而且提取结果更符合实际情况,可以为敦煌植被状况监测及生态环境保护提供科学建议。 相似文献
8.
基于DEM-NDVI的高山植被带定量刻划 总被引：2，自引：2，他引：0
根据不同高山植被类型具有不同归一化植被指数响应的特点,通过对NDVI的分析来定量刻划高山植被带的海拔分布。首先,利用DEM、NDVI构建DEM-NDVI散点分布图;然后,结合地面调查资料与WorldView-2高分遥感影像对DEM-NDVI散点分布图进行统计回归分析;最后,利用分析结果定量刻划高山植被垂直分带结构。将该方法应用于四川卧龙大熊猫保护区的卧龙关沟,结果表明：① NDVI随海拔升高而呈“Z”字形变化;② DEM-NDVI散点图比样本点DEM-NDVI分布图能更完全地表达高山植被NDVI随高程变化的特征;③ 卧龙关沟东北坡高山植被带海拔高度为3255~4415 m,西南坡高山植被带海拔高度为3193~4473 m,与地面调查得到的区域代表植被的分布高度基本一致。 相似文献
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地表覆被作为自然过程和人类活动共同作用的重要地表景观特征,对全球或局地气候、水热循环、物质传输及陆面生态系统多样性等影响深远。利用年内时序遥感影像自动提取不同地表覆被类型的方法,以新疆阜康地区为研究目标,组织2016年植被全生长季的Landsat 8 OLI地表反射时序影像,研究不同物候期植被冠层的纹理响应信息,考察研究区典型地表覆被类型在3—11月多波段波谱、归一化植被指数(NDVI)及增强型植被指数(EVI)的时序特征,构建提取地表覆被类型的策略规则,形成时序特征匹配方法,将其应用于2018年研究区地表覆被填图的提取。最后,基于高分辨率卫星影像和野外实地调查对随机选取的2500个样点进行对比验证。结果表明:提取结果和验证数据一致性较好,总体精度为97.2%,Kappa系数为0.9655,且实地考查结果显示本方法在复播作物识别和有效降低单一时相中“异物同谱”现象上展示潜在优势。 相似文献
11.
A new approach, based on the application of multi-spectral remote sensing data of Landsat imagery, is introduced to determine large-scale spatiotemporal variations of forest cover changes quantitatively and with a high degree of precision. The test area covers about 837,330.5 ha of a mountainous region in Central Italy. The approach employs several multi-temporal Landsat acquisitions to account for forest cover changes larger than 0.5 ha for the period from March 2002 to July 2011. In contrast to automated approaches that strongly curtail mapping time, the approach introduced here allowed us to map only the real forest cover change, based on a robust validation and rectification of the detected forest change. Derived high spatial resolution data of forest change estimates indicate that about 5.7% (47,670.5 ha) of the observed forest area was subject to human-induced change between 2002 and 2011. Moreover, the detected forest cover changes, most of which are identifiable as timber harvesting, are considerably larger than those reported in the official statistics and often fall within the perimeter of restricted areas (i.e., national parks and natural reserves). 相似文献
12.
George Ch. Miliaresis 《International journal of geographical information science》2013,27(7):1417-1432
A new context for active tectonic zone recognition is proposed on the basis of the exporting energy of the terrain features at continental scale. Toward this end, elevation, latitude, and longitude decorrelation stretch of multi-temporal moderate resolution imaging spectroradiometer (MODIS) monthly average land surface temperature (LST) imagery (MYD11C3) is applied in a study area extending from Red Sea to Indian Ocean and from Persian Gulf to Black Sea and Caspian Sea. Multiple linear regression analysis of principal components images (principal components analysis (PCAs)) quantified the variance explained by elevation, latitude, and longitude. Selective variance reduction reconstructed the multi-temporal LST imagery from the residual images and selected PCAs by taking into account the portion of variance that is not related to elevation, latitude, and longitude. The reconstructed imagery presents the magnitude the standardized LST value per pixel deviates from the elevation, latitude, and longitude predicted one, whereas a positive LST anomaly is defined as a region that presents positive reconstructed LST value throughout the year. Clustering of the reconstructed standardized imagery mapped a great positive LST anomaly of tectonic origin that occupies the greatest in elevation and most massive areas, forming three regions: (a) the Himalayan Belt along the Pakistan, Afghanistan borders, and the Eastern Alpine zone (Makhran Ranges and Zagros Ranges), (b) the coastal zone (along the Red Sea) of the Arabian Shield, and (c) the Oman Mountains Province along the Persian Gulf. The method will allow the classification of terrain objects (e.g. mountains, basins) on the basis of both the exporting energy (reconstructed LST) and geomorphometry. 相似文献
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Oleksandr Kit 《Applied geography (Sevenoaks, England)》2012,32(2):660-667
This paper outlines a methodology to identify informal settlements out of high resolution satellite imagery using the concept of lacunarity. Principal component analysis and line detection algorithms were applied alternatively to obtain a high resolution binary representation of the city of Hyderabad, India and used to calculate lacunarity values over a 60 × 60 m grid. A number of ground truthing areas were used to classify the resulting datasets and to identify lacunarity ranges which are typical for settlement types that combine high density housing and small dwelling size - features characteristic for urban slums in India. It was discovered that the line detection algorithm is advantageous over principal component analysis in providing suitable binary datasets for lacunarity analysis as it is less sensitive to spectral variability within mosaicked imagery. The resulting slum location map constitutes an efficient tool in identifying particularly overcrowded areas of the city and can be used as a reliable source in vulnerability and resilience assessments at a later stage. The proposed methodology allows for rapid analysis and comparison of multi-temporal data and can be applied on many developing urban agglomerations around the world. 相似文献
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Bair Z. TSYDYPOV Endon Zh. GARMAEV Arnold K. TULOKHONOV Eduard A. BATOTSYRENOV Alexander A. AYURZHANAEV Zhargalma B. ALYMBAEVA Ts. CHIMEDDORJ 《资源与生态学报(英文版)》2015,6(2):73-78
本文选择蒙古中部地区的两个模型多边形对植被多样性进行调查研究。它们都位于干旱、半干旱少雨地区。基于Landsat TM影像,本文研究了多边形区域的NDVI随时间变化的多时相NDVI值制图,得到所选择的具备不同值NDVI区域的全尺度景观特征。这一特征在对耐旱环境组的植被分析中得到了证实。该过程中将近整个实验多边形区域的植被偏离得到了追踪。NDVI的时间分布分析呈现出数值的降低,这说明了在戈壁,稀疏植被存在耐旱趋势。在半干旱气候区域中偏离植被趋势与牧草地的重载负直接相关。 相似文献
17.
PATMOS-x、ISCCP云量产品及地面观测在中国区域的对比分析 总被引：2，自引：1，他引：1
利用1986~2006年PATMOS-x 、ISCCP总云量和低云量产品与中国区域地面台站观测的总云量、低云量资料进行对比分析,对比不同来源、不同观测方法造成的云量数据在时间、空间上的差异,为资料使用者提供参考。结果表明,与台站观测资料相比,无论PATMOS-x还是ISCCP其总云量数据的空间分布、与站点观测数据的格点相关性均好于低云量数据;PATMOS-x总云量、低云量多年平均的空间分布较ISCCP更接近站点观测;中国区域平均低云量的线性趋势PATMOS-x与站点观测一致,表现为显著的上升趋势,而ISCCP低云量数据则呈现微弱的下降趋势。 相似文献
18.
基于ERDAS IMAGING软件的TM影像几何精校正方法初探--以塔里木河流域为例 总被引：11，自引：2，他引：9
遥感图像的几何精校正一直是人们所关注的问题。本文初步探讨了利用ERDAS IMAGING软件对塔里木河流域TM影像进行几何精校正的方法,ERDAS IMAGING软件进行几何精校正具有操作简便、实用性强、速度快、几何精度高等特点。几何精校正为TM影像的进一步处理提供了技术准备。 相似文献
19.
A. I. Chalmers 《New Zealand geographer》1985,41(2):96-97
There has been a marked growth in the number of spacecraft and airborne sensors since 1972, the date of the launching of the first satellite developed to monitor Earth's resources (LANDSAT). As a consequence, geographers interested in remote Sensing in New Zealand have had a widening range of data sources available to them. Geographers first expressed interest in monitoring ground cover using I.ANDSAT series data, but interest in remote sensing data has widened to include work on marine environments, structural geology, urban areas and soil survey. As Curran (1984) indicates, the development and use of thermal and microwave sensors is likely to rapidly extend the uses of remote sensing. In New Zealand, the growth in the number of stored data bases plus the increased sophistication of digital computer analysis (both dominated by the national centre, The Remote Sensing Section. DS1R) is encouraging. However, it is a matter of some concern that there does not seem to be a parallel growth in the radiometric field work required to reconcile sensor data with field information. This note examines some of the reasons which have led to this problem, stresses the importance of radiometric ground truth and describes a method of collecting radiometric data which is in operation at the University of Waikato. 相似文献
20.
A. J. Tatem H. G. Lewis P. M. Atkinson M. S. Nixon 《International journal of geographical information science》2013,27(7):647-672
Land cover class composition of remotely sensed image pixels can be estimated using soft classification techniques increasingly available in many GIS packages. However, their output provides no indication of how such classes are distributed spatially within the instantaneous field of view represented by the pixel. Techniques that attempt to provide an improved spatial representation of land cover have been developed, but not tested on the difficult task of mapping from real satellite imagery. The authors investigated the use of a Hopfield neural network technique to map the spatial distributions of classes reliably using information of pixel composition determined from soft classification previously. The approach involved designing the energy function to produce a ‘best guess’ prediction of the spatial distribution of class components in each pixel. In previous studies, the authors described the application of the technique to target identification, pattern prediction and land cover mapping at the sub-pixel scale, but only for simulated imagery. We now show how the approach can be applied to Landsat Thematic Mapper (TM) agriculture imagery to derive accurate estimates of land cover and reduce the uncertainty inherent in such imagery. The technique was applied to Landsat TM imagery of small-scale agriculture in Greece and largescale agriculture near Leicester, UK. The resultant maps provided an accurate and improved representation of the land covers studied, with RMS errors for the Landsat imagery of the order of 0.1 in the new fine resolution map recorded. The results showed that the neural network represents a simple efficient tool for mapping land cover from operational satellite sensor imagery and can deliver requisite results and improvements over traditional techniques for the GIS analysis of practical remotely sensed imagery at the sub pixel scale. 相似文献