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1.
During the summer of 1983 three Corps of Engineers project sites were overflown as part of the SPOT (Système Probatoire d'Observation de la Terre) High Resolution Visible (HRV) simulation campaign. The three sites were Chesapeake Bay, Maryland, Berlin Lake, Ohio, and Lac qui Parle, Minnesota. Multispectral imagery data at a 20-m resolution for three spectral bands (0.50–0.59 μm, 0.61–0.68 μm, 0.79–0.89 μm) were obtained for each of the sites. The data were analyzed for use in dredging, recreation resource management, water quality, and wildlife habitat applications. 相似文献
2.
The SPOT 4 VEGETATION system is a joint program of the European Commission, France, Sweden, Belgium and Italy, to be launched in 1997. It will provide global and frequent measurements adapted to biosphere studies, especially for monitoring of the biophysical processes of the vegetation canopies. Information derived from its measurements will allow operational and long term studies related either to the production of agricultural areas or to the functioning of ecosystems, to their interaction with the atmosphere and climatic changes. The design of the entire system, from the instrument to the ground segment, was aimed at providing direct capability for multitemporal analysis of surface reflectance measurements at medium spatial resolution as well as for association with high spatial resolution data sets available from the SPOT High Resolution instrument or from other systems. Nature and quality of products delivered by the system were especially tailored taking into account the development of research done on previous systems and the needs for characterizing the temporal dynamic aspects of biosphere processes and relating regional or ecosystems' parameters to local parameters less affected by spatial heterogeneity. 相似文献
3.
The SPOT satellite is designed so as to provide multispectral observations with 20 m resolution and panchromatic observation with 10 m resolution. The three spectral bands allow a study of the spectral signature of objects; so, the detailed profile of these bands has been optimized so as to select the parts of major interest in the reflectance of various objects and minimize the atmospheric perturbation in the quantitative measurement. The panchromatic band is mainly involved in cartographic application; so the design of the spectral sensitivity is related to the study of the contrast between objects thematically characterized, taking into account the actual resolution. 相似文献
4.
The problem of integrating remotely sensed images acquired from different sensor systems is primarily associated with their registration into a common reference projection. This registration problem has to be considered not only between the image data themselves but also with other data already existing in various geographical data bases.The advent of the second generation of earth observation satellites is emphasizing this situation by providing imagery in different geometric configurations. Images will be acquired from many sensors at different spatial resolutions (LANDSAT MSS and TM, SPOT HRV MLA and PLA) on different dates and modes (panchromatic, multispectral, nadir and off-nadir).In order to provide image data in a geometric format compatible with the Canadian National Topographic System, Canada is developing a Multi-Observational Satellite Image Correction System (MOSAICS) that will provide geocoded data resampled into a common reference projection. This paper presents the characteristics of the geocoded products with examples from multiple sensors and different dates, and addresses the processing requirements of the satellite ground station. It also illustrates the use of digital processing techniques to derive digital elevation information from geocoded stereo imagery. 相似文献
5.
An unmixing method for hyperspectral Earth observation satellite imagery data is proposed. It is based on a sub-space method with learning process. The proposed method utilizes a sub-space for feature space during unmixing. It is used to be done in a feature space which consists of spectral bands of observation vectors. As the results from the experiments with airborne based hyperspectral imagery data, AVIRIS, it is found that the proposed unmixing is superior to the other existing method in terms of decomposition accuracy and the process time required for the decompositions. 相似文献
6.
The first SPOT 1 images show that data quality is in fairly good agreement with the SPOT simulations on which the geological community has worked in recent years. SPOT data are particularly useful in mineral exploration for the following reasons :- ground resolution (10 m and 20 m) proves to be very effective at scales such as 1/50,000. It considerably improves the identification of secondary structural features that may be significant for mineral exploration- stereoscopy makes it possible to quantify the dip of bedding, thickness of layers, fault displacement, etc.- acquisition flexibility is an additional advantage in the case of programs requiring multitemporal data.Two examples from Western Africa are described :- Poura, Burkina Faso : gold mining prospect- Bandiagara, Mali : reconnaissance study.SPOT makes it possible to bridge the gap between the regional information provided by Landsat data and that provided by ground of large scale aerial photographic surveys, with the advantage of multispectral images. 相似文献
7.
The solar soft X-ray (XUV; 1–30 nm) radiation is highly variable on all time scales and strongly affects the ionosphere and upper atmosphere of Earth, Mars, as well as the atmospheres and surfaces of other planets and moons in the solar system; consequently, the solar XUV irradiance is important for atmospheric studies and for space weather applications. While there have been several recent measurements of the solar XUV irradiance, detailed understanding of the solar XUV irradiance, especially its variability during flares, has been hampered by the lack of high spectral resolution measurements in this wavelength range. The conversion of the XUV photometer signal into irradiance requires the use of a solar spectral model, but there has not been direct validation of these spectral models for the XUV range. For example, the irradiance algorithm for the XUV Photometer System (XPS) measurements uses multiple CHIANTI spectral models, but validation has been limited to other solar broadband measurements or with comparisons of the atmospheric response to solar variations. A new rocket observation of the solar XUV irradiance with 0.1 nm resolution above 6 nm was obtained on 14 April 2008, and these new results provide a first direct validation of the spectral models used in the XPS data processing. The rocket observation indicates very large differences for the spectral model for many individual emission features, but the differences are significantly smaller at lower resolution, as expected since the spectral models are scaled to match the broadband measurements. While this rocket measurement can help improve a spectral model for quiet Sun conditions, many additional measurements over a wide range of solar activity are needed to fully address the spectral model variations. Such measurements are planned with a similar instrument included on NASA’s Solar Dynamics Observatory (SDO), whose launch is expected in 2009. 相似文献
8.
Recent studies of the vegetation fluorescence show that it can be successfully used as an intrinsic indicator of plant photosynthetic activity. With respect to the vegetation spectral reflectance, the chlorophyll (Chl) fluorescence is more specific as an observable of basic biophysical processes in the plant cells. Laser induced fluorescence is widely used in near range remote sensing, but it is not suitable for the global monitoring of vegetation. Decades of active fluorometry studies have collected useful information of leaf reaction to natural and anthropogenic stress. Still the passive fluorescence, the one that could be registered from satellite orbit has still to prove its advantage over widely used reflectance signature. The weakness of the signal and the lack of experience with passive fluorescence measurements require extensive technical, theoretical and experimental studies. New imaging fluorometres are to be designed for measuring steady state fluorescence in controlled and natural conditions. In order to compare reflectance and steady state fluorescence sensitivity to stress impact, a set of experiments have been conducted under controlled illumination conditions in a bio-chamber, designed by the author’s team. The equipment allows plant vitality to be monitored both by passive fluorescence and spectral reflectance imaging. Different types of stress factors (heat and drought stress, acid impact) were investigated to demonstrate equipments ability in monitoring changes of fluorescence signal. Selected fluorescence images of foliage illustrate an early detection of plant dysfunction and the temporal and spatial spreading of the stress impact. Analysis shows that fluorescence imaging of green plants can be developed as a highly effective early warning remote sensing method, which could have application for an ecosystems’ monitoring along with high-spectral reflectance imagery. 相似文献
9.
对SPOT遥感图象的信息保持型压缩编码进行了研究。对几种不同的预测器及A_2、A_3线性码进行了比较,得出如下结论:在SPOT 遥感图象的信息保持型压缩编码中,采用文献[1]提出的三点预测器较好,线性码采用A_3码较好;两者结合,在信息保持率大于99%时,可使压缩比达2倍以上。文内还对在压缩图象的传输与恢复中碰到的问题进行了探讨。 相似文献
10.
Development of new methods for estimating biophysical parameters can be considered one of the most important targets for the improvement of grassland parameters estimation at full canopy cover. In fact, accurate assessment methods of biophysical characteristics of vegetation are needed in order to avoid the uncertainties of carbon terrestrial sinks. Remote sensing is a valid tool for scaling up ecosystem measurements towards landscape levels serving a wide range of applications, many of them being related to carbon-cycle models. The aim of this study was to test the suitability of satellite platform sensors in estimating grassland biophysical parameters such as LAI, biomass, phytomass, and Green herbage ratio (GR). Also, we wanted to compare some of the most common NIR and red/green-based vegetation indices with ones that also make use of the MIR band, in relation to their ability to predict grassland biophysical parameters. Ground-truth measurements were taken on July 2003 and 2004 on the Monte Bondone plateau (Italian Alps, Trento district) in grasslands varying in land use and management intensities. From satellite platforms, an IRS-1C-LISS III image (18/07/2003; 25 m resolution in the visible-NIR and 70 m resolution in the MIR) and a SPOT 5 image (27/07/2004, 10 m resolution in the visible-NIR and MIR) were used. LAI, biomass, and phytomass measurements showed logarithmic relationships with the investigated NIR and red/green-based indices. GreenNDVI showed the highest R2 values (0.59, IRS 2003; 0.60, SPOT 2004). Index saturation occurred above approximately 100–150 g m−2 of biomass (LAI 1.5–2). On the other hand, GR relationships were shown to be linear. MIR-based indices performed better than NIR and red/green-based ones in estimating biophysical variables, with no saturation effect. Biomass showed a linear regression with Canopy Index (MIR/green ratio) and with the Normalised Canopy Index (NCI) calculated as a normalised difference between MIR and green bands (IRS: R2 = 0.91 and 0.90, respectively. SPOT: R2 = 0.63 and 0.64). Similar correlations could also be found for LAI and phytomass, and GR predictability was shown to be higher than NDVI and GreenNDVI. According to these results obtained in the investigated areas, phytomass, biomass, LAI, and GR are linearly correlated with the investigated MIR band indices and as a result, these parameters could be estimated from the adopted satellite platforms with limited saturation problems. 相似文献
11.
The three highly variable ocean circulation systems which meet south of South Africa have been studied by combining the use of satellite thermal infra-red imagery, hydrographic measurements and drifting buoys. We present a few preliminary examples where this method has been successful. These include the sources of the Agulhas Current, the influence of the Agulhas Current on the Cape upwelling region as well as the interaction of the Agulhas Current with the Subtropical Convergence. An example is also given of how a biological hypothesis concerning the recruitment of a rock lobster species at Vema Seamount has been supported by the analysis of the drifts of FGGE buoys in the South Atlantic Ocean. 相似文献
12.
DORIS is a tracking system developed by CNES to support precise orbit computation of the US-French TOPEX/POSEIDON project. Moreover DORIS data are currently processed to compute SPOT2 and SPOT3 orbits. Although the SPOT satellites are at 800 km altitudes, their orbits reach the decimetric level, to be compared to the 3–4 cm RMS on the T/P radial component.For each type of orbit, there is an adaptive period of a few months which is used for improving the precision. The paper describes what has been done to reduce some items in the total error budget. The latest results will be presented as well as the criteria which are settled to characterize the improvements.Finally, the future developments of DORIS and the potential projects flowing DORIS will be outlined such as ENVISAT and TOPEX/POSEIDON Follow On. 相似文献
13.
Ocean circulation is an important element in many of the large scale experiments planned for the World Climate Program. Satellite infrared data, particularly that from polar oribiting NOAA weather satellites, have demonstrated a capability for showing flow patterns in the ocean in areas where western boundary currents or upwelling provide sufficient thermal contrast. Many areas, however, have thermal contrasts too low to be mapped reliably and other tracers are needed.Images showing variations in the colour (spectral reflectance) of the surface layers of the ocean, from the Coastal Zone Color Scanner on Nimbus 7, have provided excellent examples of flow patterns traced by movements of water bodies having different phytoplankton content. Examples are presented here which show coastal flow patterns off the British Columbia coast, Gulf Stream flow between the New England sea mounts and the form of the Alaskan Stream.Such imagery has only recently become available, and could contribute greatly to a more detailed understanding of ocean circulation. The CZCS was launched in 1978 and is slowly degrading in operation. It appears that a six-year gap in supply of ocean colour imagery may now occur before a replacement can be launched. A large back-log of data remains to be analysed. The CZCS was the first to make this type of measurement and it seems certain that improved sensor designs could increase the value of the data. One such design being developed in Canada makes use of two dimensional arrays of optical detectors to provide greatly increased spectral resolution, and improved sensitivity. 相似文献
14.
The work presents the results of the study aimed at determining the seasonal dynamics of the spectral brightness and reflectance of agricultural crops (wheat, barley and oats) in the Krasnoyarskii Krai (Russia). The analysis of spectral curves obtained through field ground measurements and from satellite data showed that fine spectral differences can be used to study the spatial distribution of various types of vegetation and their ecological state. Based on the created electronic spectral brightness data base, the possibilities are shown of using spectrophotometric information for determining morphophysiological changes occurring in the plants and their species composition. The determined contrasts can be effectively used to obtain necessary information while processing space images, which suffer from natural interferences (varying optical thickness of the atmosphere, cloudiness, alterations in the scanner’s angle of view, varying solar height, and highly inhomogeneous underlying surface). 相似文献
15.
综述了资源卫星CCD多光谱扫描仪系统像质评价的重要性。内容和影响像质的主要因素;还综述了SPOT和TM使用的评价准则、评价方法以及卫星发射前的图像质量预估和在卫星发射后的像质评估结果。 相似文献
16.
针对高分四号(GF-4)卫星影像波段较少导致传统云检测算法难以区分云与冰雪像元的问题,提出一种多时相多通道云检测算法。该算法首先对GF-4卫星影像进行辐射定标和配准,然后利用云与典型地表的光谱差异得到潜在云像元,之后利用序列GF-4卫星影像之间的差异识别出移动的云像元,最后利用中红外波段反演地表亮度温度来去除冰雪像元。该算法在海南、辽宁和安徽3个研究区域进行验证,并将检测结果与传统单时相云检测算法、支持向量机(SVM)云检测算法和实时差分(RTD)云检测算法的检测结果进行对比。结果表明,该算法优于其他3种云检测算法,准确识别率均达到90%以上,误检率均低于5%,有利于GF-4卫星影像的进一步利用。 相似文献
17.
This research focuses on the application of HyMap airborne hyperspectral data and ASTER satellite multispectral data to mineral exploration and lithologic mapping in the Arctic regions of central East Greenland. The study area is the Kap Simpson complex in central East Greenland. The Kap Simpson complex is one of the largest exposed Palaeogene felsic complexes of East Greenland. It has been the target of several mineral exploration projects. The analysis of the HyMap data produced a detailed picture of the spatial distribution of the alteration minerals in the Kap Simpson complex, unavailable from field-based studies in the area. The analysis of the ASTER data produced mineral maps which due to the moderate spatial and spectral resolution of the ASTER imagery can be useful for reconnaissance level mineral exploration. Colour composites of the mean normalized ASTER thermal bands display lithological information and detected a large felsic igneous intrusion that has not been shown on the recently compiled geological maps of the area. The results of this research have considerable potential to evaluate the use of hyperspectral and multispectral remote sensing for geological purposes in the Arctic regions of central East Greenland. 相似文献
18.
针对数字通信系统中常见的信噪比参数E b/N0,本文从功率测量、功率谱密度测量及矢量分析三个角度出发,分别给出了该参数的测量原理与方法,并通过具体测量实验比较了三种测量方法的各优缺点,对于该参数的实际工程测量具有一定指导意义。 相似文献
19.
针对数字通信系统中常见的信噪比参数E b/N 0,本文从功率测量、功率谱密度测量及矢量分析三个角度出发,分别给出了该参数的测量原理与方法,并通过具体测量实验比较了三种测量方法的各优缺点,对于该参数的实际工程测量具有一定指导意义。 相似文献
20.
The Landsat 4 and 5 Thematic Mapper (TM) provides increased spatial, spectral, and radiometric capability relative to the Multispectral Scanner (MSS). Visual inspection of TM imagery confirms this. Land cover detail is evident that would be of use in watershed management and planning activities. Specific studies have been conducted in Georgia, West Virginia, Michigan and Maryland to compare MSS and TM for urbanizing watersheds, wetlands, and floodplain mapping situations. These studies show that only modest improvements in classification accuracy (Anderson Level I/II) have been achieved using existing classification approaches. An attempt to identify the visibly apparent interstate highways and secondary and residential streets in TM data via conventional approaches failed due to an inability to derive separable spectral signatures. The basis for a non-parametric approach to classification is presented in which roads are identified by locating linear local minima in the greenness transformed dimension. Preliminary results indicate that such a method provides more reliable road locations than MSS or TM used singly. 相似文献
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