ISSN:0143-1161    

DOI:10.1080/01431169408954171

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Remote sensing data are a valuable source of information about conditions at or near the surface of the Earth if their interpretation truly reflects those conditions. One of the best ways to promote representative classifications is to gain first hand experience of ground conditions. Attempts to measure urban growth in Kathmandu improved significantly following a field trip to the city. Ground truth data were collected for accuracy assessments, spectrally confusing features were identified, and the urban land-use class was defined more appropriately in terms of Nepalese land-use patterns, rather than from the perspective of suburban Northern Virginia.

ISSN:0143-1161    

DOI:10.1080/01431169408954172

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A method for compiling soil maps from the results of digital processing of remotely-senseddata is presented. The method is based on graphic analysis of mean digital values of clusters in the green-red and (green-red)–(NIR-red) projections in conjunction with visual analysis of the cluster map and spectral curves and their interpretation on the basis of thematic maps and ground data. The proposed technique allows interpretation of the soil types of arable lands with 50 per cent vegetation density and differentiation of the soils with regard to their water regime. The accuracy of the resulting soil map was evaluated as 0·82.

ISSN:0143-1161    

DOI:10.1080/01431169408954173

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

We compared estimates of regional biomass and LAI for a tallgrass prairie site derived from ground data versus estimates derived from satellite data. Linear regression models were estimated to predict LAI and biomass from Landsat-TM data for imagery acquired on three dates spanning the growing season of 1987 using co-registered TM data and ground measurements of LAl and biomass collected at 27 grassland sites. Mapped terrain variables including burning treatment, land-use, and topographic position were included as indicator variables in the models to acccount for variance in biomass and LAI not captured in the TM data. Our results show important differences in the relationships between Kauth-Thomas greenness (from TM), LAI, biomass and the various terrain variables. In general, site-wide estimates of biomass and LAI derived from ground versus satellite-based data were comparable. However, substantial differences were observed in June. In a number of cases, the regression models exhibited significantly higher explained variance due to the incorporation of terrain variables, suggesting that for areas encompassing heterogeneous landcover the inclusion of categorical terrain data in calibration procedures is a useful technique.

ISSN:0143-1161    

DOI:10.1080/01431169408954174

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The NDVI profile computed from coarse resolution satellite records over temperate agricultural countries, is an average profile which results from the combination of radiative responses of the different species which are found within a pixel. In this paper we are interested in the extraction of the NOVI time profile of some specific crops using a semi-empirical model to test for the temporal variations of the NDVI. First, a simple model (a double logistic function with five parameters) is used to describe the temporal profile of the NOVI over an homogeneous canopy. The two parameters which locate the inflexion points, are particularly interesting to define the growing period. In this paper, we assume that, from a radiative point of view, the Beauce agricultural country (France) can be assimilated to an association of two homogeneous canopies: winter crops group and summer crops group. The double logistic functions which describe the NOVI time profile for these two groups are: NDVIw(t) and NDVIs,(t). Second, in such a case, an approximate model based on the sum of NDVIw(t) and NDVIs,(t) weighted by the areas, can describe the NOVI temporal data at a regional scale. A sensitive study is done, in order to examine how the application of this model to Regional Data permits the retrieval of parameters values close to that of NDVIw(t) and NDVIs,(t). The results show that with an a priori knowledge on the asymptotical value of each double logistic function, the positions of the inflexion points are retrieved with a maximum error of 6 per cent when the relative contributions of winter crops and summer crops are nearly the same, when an error of 11 per cent is reached for the location of the growing period of the summer crops and when their contribution to the regional response is reduced.

ISSN:0143-1161    

DOI:10.1080/01431169408954175

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Based on the soil line concept, various kinds of vegetation indices have been proposed to minimize soil background influences in the inventory of forest resources and the prediction of vegetation biomass. Unfortunately, those indicescan only reduce soil moisture effect on remote sensing data parallel to the axis, the direction of the so-called soil line, failing when different soil types appear (in the direction perpendicular to the soil line). A two-axis adjusted vegetation index is presented here to diminish most soil background influences. It is shown to be more suitable as a global monitoring vegetation index than other indices.

ISSN:0143-1161    

DOI:10.1080/01431169408954176

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Some red edge parameters in the first derivative reflectance curve (wavelength, amplitude and area of the red edge peak) were studied to evaluate plant chlorophyll content, biomassand RelativeWater Content (RWC).Plants of Capsicum annuum and Phaseolus vulgaris under different nitrogen and water availabilities, and plants of Gerbera jamesonii with different hydric status were studied. A high correlation was found between chlorophyll content and the wavelength of the red edge peak (λre), and between LAI (leaf area index)and the amplitude of the red edge peak (drr e), but the area of the red edge peak (σ680–780nm) was the best estimator of LAI. Thus, red edge was found valuable for assessment of plant chlorophyll concentration and LAI, and therefore nutritional status. Water stress also affected drre, but only when the stress was well developed.

ISSN:0143-1161    

DOI:10.1080/01431169408954177

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The present work is an integrated photogeological-geophysical study which deals essentially with the delineation and analysis of the structural lineament pattern in the surroundings of the Aswan region, with special emphasis on the North Lake Nasser area to the south of Aswan, upper Egypt. This integrated study is based mainly on the utilization of the structural lineaments map of the southeastern desert of Egypt interpreted from the Landsat-I Satellite images in addition to the aerial photomosaics and aeromagnetic maps of North Lake Nasser area. Results obtained have been used in conjunction with the previously available seismological information in delineating sites of potential earthquake activity in the North Lake Nasser area.

ISSN:0143-1161    

DOI:10.1080/01431169408954178

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The study area is well known for the historical Cu/Mn mineralization at Khirbet El Nahas. A map of alteration zones was prepared by Kaufmann in 1988, based on Landsat-TM data. During 1 :50000 geological field mapping, with associated imagery studies, a moe specificdelineation of the metallically mineralized parts of the alteration zones was achieved and the structural control on the distribution of minerals was defined. Different Landsat-TM band combinations, including colour composite of bands 7, 4, and 2, high pass filtering of the colour composite of bands 7, 5 and 2, ratio and principal component colour composites, were used to enhance diagnostic features of mineralized zones, preform analysis of structural features and to verify the distribution of certain lithological units. A number of target areas were examined in the field and selectively sampled. As a result, previously known mineralized zones were defined and new mineralization areas were discovered.

ISSN:0143-1161    

DOI:10.1080/01431169408954179

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The paper discusses the design of an Alpine Snow Cover Analysis System (ASCAS) for monitoring snow cover variations in the Alps. It is shown how data such as snow cover data derived from satellite, climate, hydrologic, and topographic data, are programmed into the system. Possible techniques for analysing snow cover variations and results are presented. Furthermore, the integration of image processing and GIS techniques with applied models on a microcomputer-based system is described.

ISSN:0143-1161    

DOI:10.1080/01431169408954180

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor