ISSN:0143-1161    

DOI:10.1080/01431168708948610

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Results are presented from studies of bare soils conducted during the NERC MSS-82, -83 and -84 campaigns. Test areas throughout southern and eastern England were selected to represent a wide range of British soils, and data from these sites are discussed in relation to the problems of intercalibrating ground and airborne data, as well as the effects of solar-sensor geometry on such intercalibration.

ISSN:0143-1161    

DOI:10.1080/01431168708948611

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A study is made to assess the effect of spatial resolution on the degree of internal variability within land-cover classes and then to examine how this within-class variance affects classification accuracy. Airborne Multispectral Scanner data flown at 5 m resolution are degraded to simulate 10 and 20 m data. Classification accuracies within internally homogeneous classes are found to be high at all spatial resolutions. In contrast, classification accuracies of land-cover types characterized by a high degree of internal variability or scene noise improve by up to 20 per cent as spatial resolution is coarsened because the proportion of scene noise is reduced. A further improvement in classification can be achieved by smoothing the imagery prior to classification using various spatial filters. The extent of this improvement was found to be as much as 25 per cent depending on the type of spatial filter used, the window size of the filter, the spatial resolution of the data and the land-cover type being classified.

ISSN:0143-1161    

DOI:10.1080/01431168708948612

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Preliminary results are presented from a study of heathland in the New Forest, southern England, using ground radiometry and airborne multispectral survey. Spectral data collected at ground level with a 1 m sampling cell size showed considerable internal variability for most of the vegetation types studied, and much overlap between classes in the multispectral feature space. The airborne scanner data (5 m nominal pixel size) averaged out the spatial variability in reflectance to some extent, and suggested that limited spectral discrimination between some of the vegetation types may be possible. However, effective remote sensing of structurally complex canopies such as shrubs, requires an understanding of the three-dimensional form of the spectral reflectance function and its relationship to the geometric arrangement of canopy components and to phenological changes in the canopy.

ISSN:0143-1161    

DOI:10.1080/01431168708948613

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Simulated Thematic Mapper (TM) data are examined for an area of the North Yorks Moors, northern England. The aim of analysis is to determine the number and identity of wavebands needed to distinguish specific moorland vegetation types from the surrounding community. The interband correlation and dimensionality of the data are found to be different for each of the vegetation types studied. Calculation of the transformed divergence measure shows that the major communities of bracken, heather and sedges are clearly separated with the use of one or two wavebands; four or five bands are needed to distinguish the stages of heather growth. In all cases, the combination of wavebands which maximizes discrimination is specific to the vegetation types to be separated. The work has practical implications for the use of TM data in the monitoring of the moorland landscape.

ISSN:0143-1161    

DOI:10.1080/01431168708948614

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Airborne multispectral scanner ( MSS) data, collected in June 1984, were used to estimate the green leaf area index ( GLAI) for 60 km2 of grassland. The methodology involved (i) radiometric and atmospheric correction, (ii) production of a vegetation index image, (iii) calculation of a calibration relationship between a vegetation index and GLAI, (iv) production of an image of estimated GLAI by inversion of the calibration relationship in (iii), and (v) accuracy assessment. The initial accuracy of GLAI estimation was ± 0-75 GLAI for an area and 17-40 per cent at the 95 per cent confidence level, for a six-class classification. Refinements to the methodology were evaluated by their effect upon the accuracy of GLAI estimation. In order of increasing importance these refinements were: suppression of environmental effects on the remotely sensed data, processing on a per-field rather than a per-pixel basis, calculation of the calibration relationship between a vegetation index and GLAI, using ground-based radiometric data and a modified least-squares regression up to the asymptote of the vegetation index and allowance for error in the ground data. By utilizing all of these refinements the accuracy of GLAI estimation increased to + 009 GLAI for an area and 60-82 per cent at the 95 per cent confidence level, for a five-class classification.

ISSN:0143-1161    

DOI:10.1080/01431168708948615

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Multispectral scanner (MSS) data from a series of four flights over the Edinburgh sea outfall in the Firth of Forth have been analysed. The data reveal the existence of an integrated surface sewage plume resulting from discharge from a number of sub-surface vertical riser pipes connected to an outfall tunnel. After further processing, the structure of the plume is delineated and the existence of discrete sources of discharge within the plume is demonstrated. The capability to locate such sources with processed MSS data and thereby to monitor the performance of the outfall has significant commercial implications. Failure of the outfall system to discharge as designed (i.e. fully through all risers) can lead to marine growth and sedimentation within it and eventual long-term damage. The methods used ( principal components analysis, contrast stretching, etc) to process the MSS data to serve as monitoring tools are described.

ISSN:0143-1161    

DOI:10.1080/01431168708948616

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Airborne Thematic Mapper data from the NERC MSS-82 campaign in Swansea Bay, Bristol Channel, have been correlated, in linear and multiple regression analyses, with measured water quality parameters: suspended sediment concentration ( SSC) mean grain size of material in suspension, surface salinity and chlorophyll-a concentrations. The investigation is an extension of that carried out by Collins and Pattiaratchi (1984). The spectral wavelengths providing maximum information on the distribution and concentrations of water quality parameters are determined. The conclusions reached are compared with those of other investigators. It is shown that particle size influences the spectral signature of suspended sediment, and that there is a masking effect of high SSCs on the spectral reflectance of chlorophyll. Multiple regression equations are derived and applied to the digital remotely-sensed data, to produce thematic maps of water quality. The maps are compared to the sea-truth data. It is concluded that airborne remote sensing provides a useful means of mapping surface water quality in coaslal regions.

ISSN:0143-1161    

DOI:10.1080/01431168708948617

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The till that comprises the coastal cliffs at Holderness is being eroded and transported southwards by waves and currents within the nearshore zone. As a first step towards estimating the magnitude of this movement, airborne multispectral scanner data were collected. The spectral radiance ( Lλ ) recorded by this sensor was positively correlated with the suspended sediment concentration ( SSC) at the 95 percent confidence level. However, when the relationships between SSC and Lλwere inverted for the estimation of SSC, errors of the order of 343-494 percent were observed. It is recommended that for future studies there is a need to reduce the errors consequent upon the areal, vertical and temporal variability in SSC, the problems of inversion and the presence of white-caps.

ISSN:0143-1161    

DOI:10.1080/01431168708948618

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Daedalus Airborne Thematic Mapper ( ATM) data, obtained between 12.14GMT and 13.44GMT on 19 June 1984 as part of the Natural Environment Research Council's Airborne MSS-84 campaign, have been used to calculate sea surface temperatures in the western English Channel. Quantitative analyses of the thermal infrared data are discussed with particular reference to boat trials and eddy structures. A method to calculate brightness temperatures and their associated errors is also discussed along with a review of two atmospheric correction procedures for the estimation of sea surface temperatures from thermal infrared data. An apparent asymmetry in the thermal infrared data is considered in the context of the atmospheric correction model used. Results show that the asymmetry can be compensated by using an effective scanner tilt angle.

ISSN:0143-1161    

DOI:10.1080/01431168708948619

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor