摘要:

A spectral image classifier is a rule which relates colour/brightness in a digital image to classes of interest. After an image has been classified, areas can be estimated by counting the number of pixels in each class. This paper presents a simple formula for calculating the accuracy of these area estimates from the confusion matrix. The formula gives the root mean square (r.m.s.) error of the area of class c, in pixel units, as the number or image pixels times the square root of {the sum of the off-diagonal elements in row c and column c of the confusion matrix}, divided by the number of samples in the confusion matrix. The formula is valid for confusion matrices sampled using any non-stratified scheme.

ISSN:0143-1161    

DOI:10.1080/01431169208904223

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A new cross-correlation algorithm is presented for the analysis of remotely sensed reflected spectra. Enhancement factors are defined which allow for comparison with existing techniques. This new algorithm is then used to detect the presence of rhodamine-B dye at ppb (109) concentrations, in sea water.

ISSN:0143-1161    

DOI:10.1080/01431169208904224

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The radiative effects of atmospheric aerosols on the retrieval of sea surface temperature from the infrared radiances measured in Channels 3(∼ 3·55−3·95µm), 4(∼ 10·30−11·30µm), and 5(∼ 11·50−12·50µm) of the Advanced Very High Resolution Radiometer (AVHRR) onboard the NOAA polar-orbiting operational environmental satellites have been simulated in realistic models of a turbid atmosphere above the sea surface at a given temperature. The LOWTRAN-7 radiative transfer code has been used to compute the upwelling radiances at the central wavenumbers of these three channels. Brightness temperatures computed from these radiances were used in the NOAA/ NESDIS Multichannel Sea Surface Temperature (MCSST) retrieval algorithms to calculate sea surface temperatures. It is observed that the calculated (retrieved) sea surface temperatures are always less than the prescribed value in the model atmosphere, with the depressions ranging up to 4°C, depending upon the type and total columnar abundance of aerosols, prescribed sea surface temperature, and the satellite zenith angle of observation. The modelled sea surface temperature depressions show a high degree of correlation with the line-of-sight aerosol optical thickness; linear regression yields values in excess of 0·8 for the coefficient of determination.

ISSN:0143-1161    

DOI:10.1080/01431169208904225

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A method is defined for the estimation of the strength of signal present in spectral data sets which are dominated by background and noise effects. The method is particularly well suited to data in cases where a considerable body of observations is available for calibration purposes. The spectral characteristics of the required signal as it affects the data, the ‘key vector’, is determined by Singular Value Decomposition and optimised using the known constituent data. A simulation is performed to illustrate the determination of the key vector and its use to estimate constituent content on subsequent data sets.

ISSN:0143-1161    

DOI:10.1080/01431169208904226

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This study aims to (i) investigate the relationship between spectral radiance recorded by the Landsat Thematic Mapper and the volume (m3 ha−1) of forest compartments in a coniferous forest area in southern Sweden and (ii) establish and evaluate a regression for volume estimation of forest compartments. A regression of volume on spectral radiance of TM5 was established with Wald's method.

ISSN:0143-1161    

DOI:10.1080/01431169208904227

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

NOAA-11/AVHRR data from March 1990 to February 1991 have been processed to map the vegetation cover of France with a 4 km spatial resolution. After an automatic cloud detection, Normalized Difference Vegetation Index (NDVI) were computed over the whole period using visible and near-infrared reflectances corrected for atmospheric effects. Monthly NDVI values were obtained for each point of the area by keeping the maximum value. These annual profiles have been classified with a clustering algorithm and the resulting classification has been associated to vegetation cover by comparison with the 1988 vegetation survey from the French Agriculture Department.

ISSN:0143-1161    

DOI:10.1080/01431169208904228

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The study presented here is a part of an attempt to improve the operational algorithm used at the Centre de Météorologie Spatiale (CMS) to calculate Sea Surface Temperature (SST) from Advanced Very High Resolution Radiometer (AVHRR) data. The errors produced by SST retrieval algorithms are analysed through two experiments: an examination of the errors calculated on a validation file and an analysis of the temperatures of oceanic cloud-free areas seen under two distinct satellite zenith angles (θ) for consecutive night-time orbits. This Letter presents the part of the study dedicated to the effect of large viewing angles on the retrieval of SST. Correction terms are proposed and compared, on the same set of data, to split window algorithms using θ dependent coefficients

ISSN:0143-1161    

DOI:10.1080/01431169208904229

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor