共查询到20条相似文献，搜索用时 46 毫秒
1.
Remote sensing has recently been used to map forage quality for rangeland management. However, the validity of the remotely sensed forage quality can best be assessed when it connects well with the animal unit. In this study we used the new WorldView-2 multispectral imagery to estimate and map forage quality (nitrogen concentration) as a step to explain GPS based cattle distribution in a rangeland of Southeastern Zimbabwe. Nitrogen concentration was successfully estimated and mapped (Rcv2 = 0.66, relative error = 0.13%) using partial least squares regression (PLSR). The integration of GPS based cattle distribution patterns with forage quality in a GIS showed that cattle locations significantly clustered in areas of high forage quality. The results of this study suggest that new multispectral data with unique band settings such as WorldView-2 improves the estimation and mapping of forage quality in rangelands at landscape level. In addition, our results indicate that remotely sensed forage quality can be used to explain herbivore distribution, particularly cattle grazing patterns in rangelands. 相似文献
2.
Tropical deforestation through logging activities poses a direct threat to biodiversity. However, the detection of logging has remained a challenge. Based on study sites in Zimbabwe and Zambia, we tested whether the Normalized Difference Vegetation Index (NDVI) and the Coefficient of Variation in NDVI (CVNDVI) derived from high and medium spatial resolution satellite data could be used to detect logging in dry and wet miombo woodlands. Separately, we integrated NDVI and CVNDVI in logistic regression to test whether each can be used to successfully predict logging in the study sites. We tested whether the spatial resolution of satellite data has an effect in detection of logging using NDVI and CVNDVI derived from Landsat 8 and Worldview-2. Based on the ROC curves, we concluded that remotely sensed data could provide an effective predictive tool for detecting logging. However, in wet miombo woodlands the predictive power of remotely sensed data is weak. 相似文献
3.
In this study, we tested the utility of remotely sensed data in predicting tree species diversity in savanna woodlands. Specifically, we developed linear regression functions based on a combination of the coefficient of variation of near infrared (NIR) radiance and the soil-adjusted vegetation index (SAVI), both derived from advanced space-borne thermal emission and reflection radiometer satellite imagery. Using the regression functions in a Geographic Information System (GIS), we predicted the spatial variations in tree species diversity. Our results showed that tree species diversity can be predicted using a combination of the coefficient of variation of NIR radiance and SAVI. We conclude that remotely sensed data can be used to spatially predict tree species diversity in savanna woodlands. 相似文献
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5.
C. R. Suribabu J. Bhaskar T. R. Neelakantan 《Journal of the Indian Society of Remote Sensing》2012,40(4):699-708
The rapid growth of urban population in India is a cause of concern among country??s urban and town planners for efficient urban planning. The drastic growth of urban areas has resulted in sharp land use and land cover changes. In recent years, the significance of spatial data technologies, especially the application of remotely sensed data and geographical information systems (GIS) has been widely used. The present study investigates the urban growth of Tiruchirapalli city, Tamilnadu using IRS satellite data for the years 1989, 1992, 1995, 1998, 2001, 2004, 2007, and 2010. The eight satellite images are enhanced using convolution spatial enhancement method with Kernel (7?×?7) edge enhance function. Supervised classification method is used to classify the urban land use and land cover. The GIS is used to prepare the different layers belonging to various land uses identified from remotely sensed data. The analysis of the results show the drastic increase of built up area and reduced green cover within the city boundary limit. 相似文献
6.
《International Journal of Digital Earth》2013,6(2):115-142
Abstract On site observation is the most common way of monitoring cultural heritage sites and monuments in Cyprus. However, this procedure that includes data collection, periodical observations, and multivariate risk assessment analysis is difficult to accomplish with the traditional practices and methods since it is time consuming and expensive. Furthermore, many archaeological sites and monuments are located at inaccessible areas, far away from the main road network and urban areas. Satellite remote sensing and Geographical Information Systems (GIS) can successfully confront this problem by providing the scientists with integrated monitoring of the study areas and the unique advantage to store and manipulate a large amount of spatial and attribute data simultaneously. Actually the monitoring and identification of several natural and anthropogenic hazards in the vicinity of the cultural heritage sites in Cyprus, seems to be one of the main priorities of its governmental and municipal authorities. This study aims to integrate both satellite remote sensing techniques and GIS in a multidisciplinary approach, for monitoring anthropogenic and natural hazards with the use of archived and up-to-date multitemporal remotely sensed images in the study area, namely in areas nearby cultural heritage sites and monuments in Cyprus. In this study anthropogenic hazards include urbanisation and extended land use changes in the surroundings of archaeological sites and natural hazards concern seismicity and sea erosion. 相似文献
7.
Metropolitan Beijing is facing many environmental problems such as haze and urban heat island due to the rapid urbanization. Surface shortwave, longwave, and net radiations are key components of the surface-atmosphere radiation budget. Since megacities are affected by the thermal radiation of complex landscape structures and atmospheric environments, quantitative and spatially explicit retrieval from remotely sensed data remains a challenge. We collected the surface radiation fluxes from seven fixed sites representing different land-use types to calibrate the local parameters for remotely sensed retrieval of net radiation. We proposed a remote sensing–based surface radiation retrieval method by embedding the underlying land covers and integrating the observational data. The improved method is feasible to accurately retrieve surface radiation and delineate spatial characteristics in metropolitan areas. The accuracy evaluation indicated that the difference between remotely sensed and in situ observed net radiation ranged within 0~± 40 W· m?2. The root mean squared error of the estimated net surface radiation was 32.71 W· m?2. The strongly spatial heterogeneity of surface radiation components in metropolitan Beijing was closely related to land-cover patterns from urban area to outskirts. We also found that the surface net radiation had a decreasing trend from 1984 to 2014, and the net radiation in the urban area was lower than that in the outskirts. According to the surface radiation budgets, urbanization resulted in the cooling effect in net radiation flux in the daytime, which was stemmed from low atmospheric transmittances from massive aerosol concentration and high surface albedo from light building materials. 相似文献
8.
Gohar Ghazaryan Olena Dubovyk Valerie Graw Nataliia Kussul Jürgen Schellberg 《地理信息系统科学与遥感》2020,57(5):704-718
ABSTRACT Globally, drought constitutes a serious threat to food and water security. The complexity and multivariate nature of drought challenges its assessment, especially at local scales. The study aimed to assess spatiotemporal patterns of crop condition and drought impact at the spatial scale of field management units with a combined use of time-series from optical (Landsat, MODIS, Sentinel-2) and Synthetic Aperture Radar (SAR) (Sentinel 1) data. Several indicators were derived such as Normalized Difference Vegetation Index (NDVI), Normalized Difference Moisture Index (NDMI), Land Surface Temperature (LST), Tasseled cap indices and Sentinel-1 based backscattering intensity and relative surface moisture. We used logistic regression to evaluate the drought-induced variability of remotely sensed parameters estimated for different phases of crop growth. The parameters with the highest prediction rate were further used to estimate thresholds for drought/non-drought classification. The models were evaluated using the area under the receiver operating characteristic curve and validated with in-situ data. The results revealed that not all remotely sensed variables respond in the same manner to drought conditions. Growing season maximum NDVI and NDMI (70–75%) and SAR derived metrics (60%) reflect specifically the impact of agricultural drought. These metrics also depict stress affected areas with a larger spatial extent. LST was a useful indicator of crop condition especially for maize and sunflower with prediction rates of 86% and 71%, respectively. The developed approach can be further used to assess crop condition and to support decision-making in areas which are more susceptible and vulnerable to drought. 相似文献
9.
As an important GIS function, spatial interpolation is one of the most often used geographic techniques for spatial query, spatial data visualization, and spatial decision-making processes in GIS and environmental science. However, less attention has been paid on the comparisons of available spatial interpolation methods, although a number of GIS models including inverse distance weighting, spline, radial basis functions, and the typical geostatistical models (i.e. ordinary kriging, universal kriging, and cokriging) are already incorporated in GIS software packages. In this research, the conceptual and methodological aspects of regression kriging and GIS built-in interpolation models and their interpolation performance are compared and evaluated. Regression kriging is the combination of multivariate regression and kriging. It takes into consideration the spatial autocorrelation of the variable of interest, the correlation between the variable of interest and auxiliary variables (e.g., remotely sensed images are often relatively easy to obtain as auxiliary variables), and the unbiased spatial estimation with minimized variance. To assess the efficiency of regression kriging and the difference between stochastic and deterministic interpolation methods, three case studies with strong, medium, and weak correlation between the response and auxiliary variables are compared to assess interpolation performances. Results indicate that regression kriging has the potential to significantly improve spatial prediction accuracy even when using a weakly correlated auxiliary variable. 相似文献
10.
In many regions, a decrease in grasslands and change in their management, which are associated with agricultural intensification, have been observed in the last half-century. Such changes in agricultural practices have caused negative environmental effects that include water pollution, soil degradation and biodiversity loss. Moreover, climate-driven changes in grassland productivity could have serious consequences for the profitability of agriculture. The aim of this study was to assess the ability of remotely sensed data with high spatial resolution to estimate grassland biomass in agricultural areas. A vegetation index, namely the Normalized Difference Vegetation Index (NDVI), and two biophysical variables, the Leaf Area Index (LAI) and the fraction of Vegetation Cover (fCOVER) were computed using five SPOT images acquired during the growing season. In parallel, ground-based information on grassland growth was collected to calculate biomass values. The analysis of the relationship between the variables derived from the remotely sensed data and the biomass observed in the field shows that LAI outperforms NDVI and fCOVER to estimate biomass (R2 values of 0.68 against 0.30 and 0.50, respectively). The squared Pearson correlation coefficient between observed and estimated biomass using LAI derived from SPOT images reached 0.73. Biomass maps generated from remotely sensed data were then used to estimate grass reserves at the farm scale in the perspective of operational monitoring and forecasting. 相似文献
11.
Vishakha T. Dongare G. P. Obi Reddy A. K. Maji I. K. Ramteke 《Journal of the Indian Society of Remote Sensing》2013,41(1):91-104
The present investigation has been designed to analyze the landform and soil relationship in a geologically complex terrain of Tirora tahsil of Gondia district, Maharashtra using remotely sensed data and GIS technique. The geomorphologic units of the study area were delineated through visual interpretation of IRS–ID LISS-III data based on the spatial variation of the image characteristics. Thirteen landform units have been identified in the tahsil. The slope varied from level to nearly level with an area of about 63.76% of the tahsil. Rest of the area ranged from very gentle to moderately steep slopes. During soil survey, soil profiles were studied for morphological features. Horizon-wise soil samples were collected from the representative soil profiles on each landform unit. The depth of soil varied from 25 to 160 cm and colour from dark brown to very dark grayish brown. The texture ranged from clay loam to clayey in accordance with higher and lower topographic positions respectively. Higher available water holding capacity (AWC 285 mm) is found in low-lying area and low to medium AWC (140 mm) is noticed in the soils developed at higher elevation. The soils reaction (pH) is strongly acidic in nature (pH 5.2) on dissected hills, linear ridge and moderately weathered pediments, whereas, the soils are moderately to slightly acidic in nature (pH 5.5 to 6.5) on hills, shallow weathered pediments, moderately weathered pediments, deeply weathered pediments, narrow valleys, and broad valley floors. Slightly alkaline condition (pH 7.6) was observed on foot slopes and aggraded valley fills. The electrical conductivity of the soils is found almost same in all landforms. The cation exchange capacity of the area varies from 10.5 to 51.5 cmol(p+)kg?1. The base saturation increases with decreasing elevation and slope. The four major soil orders viz, Entisols, Alfisols, Inceptisols and Vertisols are found in the study areas which are further classified into suborder and great group levels. The landform and soil relationship was analyzed to appraise the land resources in the tahsil. The study shows that the application of remotely sensed data and GIS are immensely helpful in land resources appraisal for their management on sustainable basis. 相似文献
12.
基于频域滤波的高分辨率遥感图像城市河道信息提取 总被引：2，自引：0，他引：2
提出一种基于频域滤波的城市河道信息提取方法。首先对高分辨率遥感图像进行傅里叶变换得到频谱图, 并利用径向和角向分布图分析城市河道的频谱特征。其次, 基于城市河道的双线型特点, 将其分为边缘特征和低频信息两个部分, 并根据周期性纹理的频谱模型和地物频谱能量分布规律确定两个部分的频域识别标志。然后设计相应的扇环形带通log Butterworth滤波器和低通Butterworth滤波器分别对城市河道的边缘特征和低频信息进行提取, 并根据该两部分信息实现城市河道信息提取。最后对城市河道信息提取结果进行定量评价, 结果表明, 本文方法可以有效地实现城市河道的信息提取。 相似文献
13.
The aim of this study is to compare the changes that occurred in the main urban land-cover classes of Ulaanbaatar city, Mongolia, during a centralized economy with those that occurred during a market economy and to describe the socio-economic reasons for the changes. For this purpose, multi-temporal remote sensing and geographical information system (GIS) data sets, as well as census data, are used. To extract the reliable urban land-cover information from the selected remotely sensed data sets, a refined parametric classification algorithm that uses spatial thresholds defined from local and contextual knowledge is constructed. Before applying the classification decision rule, some image fusion techniques are applied to the selected remotely sensed data sets to define the most efficient fusion method for training sample selection and for defining local and contextual knowledge. Overall, the study indicates that during the centralized economy significant changes occurred in a ger area of the city, whereas during the market economy the changes occurred in all areas. 相似文献
14.
In this study, we tested whether the inclusion of the red-edge band as a covariate to vegetation indices improves the predictive accuracy in forest carbon estimation and mapping in savanna dry forests of Zimbabwe. Initially, we tested whether and to what extent vegetation indices (simple ratio SR, soil-adjusted vegetation index and normalized difference vegetation index) derived from high spatial resolution satellite imagery (WorldView-2) predict forest carbon stocks. Next, we tested whether inclusion of reflectance in the red-edge band as a covariate to vegetation indices improve the model's accuracy in forest carbon prediction. We used simple regression analysis to determine the nature and the strength of the relationship between forest carbon stocks and remotely sensed vegetation indices. We then used multiple regression analysis to determine whether integrating vegetation indices and reflection in the red-edge band improve forest carbon prediction. Next, we mapped the spatial variation in forest carbon stocks using the best regression model relating forest carbon stocks to remotely sensed vegetation indices and reflection in the red-edge band. Our results showed that vegetation indices alone as an explanatory variable significantly (p < 0.05) predicted forest carbon stocks with R2 ranging between 45 and 63% and RMSE ranging from 10.3 to 12.9%. However, when the reflectance in the red-edge band was included in the regression models the explained variance increased to between 68 and 70% with the RMSE ranging between 9.56 and 10.1%. A combination of SR and reflectance in the red edge produced the best predictor of forest carbon stocks. We concluded that integrating vegetation indices and reflectance in the red-edge band derived from high spatial resolution can be successfully used to estimate forest carbon in dry forests with minimal error. 相似文献
15.
RS与GIS一体化数据结构的研究 总被引：1，自引：0，他引：1
详细阐述了RS与GIS一体化的概念 ,通过对RS与GIS一体化方面的研究与分析 ,进一步明确RS与GIS一体化对空间数据存储结构的要求 ,着重探讨了几种典型的用于RS与GIS一体化的数据结构 ,针对现有数据结构存在的问题与不足 ,提出了一种具有普遍适用价值的基于语义网络的空间数据存储结构 ,并给出一个应用实例 相似文献
16.
斯里兰卡亚洲象栖息地是全球重要的亚洲象保护区,象群分布密度约为其他地区的10倍,但由于生境破碎与丧失以及人象冲突等原因导致亚洲象数量急剧下降。对斯里兰卡亚洲象栖息地的生境质量监测与评估能够为亚洲象及其栖息地的保护政策制定与规划提供理论依据,并在全球物种多样性保护中具有重要意义。为评估斯里兰卡亚洲象栖息地的生境质量,综合考虑亚洲象栖息地需求以及影响亚洲象栖息地的关键要素,应用InVEST-HQ模型来估算生境质量指数,同时分析亚洲象栖息地生境质量在海拔梯度及植被覆盖梯度上的分布状况;随后引入空间自相关分析方法在像元尺度上探讨亚洲象栖息地生境质量的空间分布模式与时间演化过程,进而分析栖息地内不同保护区和气候分区的生境质量所存在的空间分异特征。研究结果表明：在空间分布上,斯里兰卡亚洲象栖息地生境质量具有高度聚集性,空间异常值不显著。生境质量高值区主要集中在中低海拔、植被覆盖情况较好、保护区范围密集的区域;生境质量低值区集中于耕地面积大、海拔偏高的区域。在梯度分布上,斯里兰卡亚洲象栖息地生境质量对海拔和植被覆盖度均具有显著线性相关关系,且在较低海拔和较高植被覆盖度梯度上存在聚集现象。在区域尺度上,斯里兰卡亚洲象栖息地生境质量存在显著的地域差异性。栖息地内自然保护区的生境质量明显高于非自然保护区,其中严格自然保护区的生境质量相对较高;热带雨林气候带的生境质量高值聚类大于其余气候分区,而热带疏林草原气候带与热带季风气候带生境质量受到季节性降水的影响较大,高值像元占比偏少。在时间尺度上,斯里兰卡亚洲象栖息地的生境质量总体呈现先降低后趋于平缓的态势。1995年—2010年,生境质量高值聚类占比明显减少,低值聚类占比缓慢上升;2010年—2020年生境质量低值占比有小幅度下降,高值聚类逐渐增加,生境质量逐渐稳定并呈缓慢上升的趋势。 相似文献
17.
Ajay Mathur P K Litoria P K Sharma M H Kalubarme 《Journal of the Indian Society of Remote Sensing》1998,26(4):209-214
The present study attempts to conceptualise an approach to integrate the remotely sensed and spatial?n-spatial data generated over the years under Crop Acreage and Production Estimation (CAPE) project through GIS for their easy retrieval and comparison; and to develop a program in dBASE to calculate crop acreage using non-spatial attributes imported from GIS. The “Crop Information System” thus developed would help the planners in analysis/comparison of the database related to crops over the years. 相似文献
18.
Quang-Thanh Bui Quoc-Huy Nguyen Van Manh Pham Minh Hai Pham Anh Tuan Tran 《国际地球制图》2013,28(12):1300-1314
AbstractThis study examines the potentials of remotely sensed data, GIS and some machine learning classifiers and ensemble techniques in the investigation of the non-linear relationship between malaria occurrences and socio-physical conditions in the Dak Nong province of Viet Nam. Accuracy assessment was determined with Receiver Operating Characteristic (ROC) curve and pair t-test. The results showed that the area under ROC of Random Subspace ensemble model performed better than the other models based on statistical indicators. Comparing pair t-test with Area Under Curve values showed a slight difference of about 1%. Therefore ensemble techniques had significantly improved the performance of the base classifier. However, the performances might vary according to geographic locations. It is concluded that the machine learning classifiers combined with remotely sensed data and GIS is promising for malaria vulnerability mapping, and the derived maps can be used as a fundamental basis for programmes on spatial disease control. 相似文献
19.
基于多源遥感数据的水体信息提取研究 总被引：1，自引：0，他引：1
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。 相似文献
20.
《制图学和地理信息科学》2013,40(3):153-165
With the progress of mobile GIS technology there is a great potential for adopting wireless communications and Internet mapping services for regional environmental management programs and natural habitat conservation. This paper provides an overview of a NASA-funded research project that focuses on the development of mobile GIS tools and wireless Internet Map Server (IMS) services to facilitate environmental monitoring and management tasks. By developing and testing wireless web-based map/image servers, mobile GIS applications, and global positional systems (GPS), this research created an integrated software/hardware infrastructure for a prototype mobile GIS application. The mobile GIS prototype allows multiple resource managers and park rangers to access large-size, remotely sensed images and GIS layers from a portable web server mounted in a vehicle. Users can conduct real-time spatial data updates and/or submit changes back to the web server over the wireless local area network (WLAN). This paper discusses in general the major components of mobile GIS, their current technological limitations, and potential problems during implementation. Key research agenda for mobile GIS are identified with suggestions for future research and development. 相似文献