ISSN:0143-1161    

DOI:10.1080/01431169208904129

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Texture features have proved to be an important tool in image segmentation and object recognition, as well as interpretation of images in a variety of applications ranging from medical imaging to remote sensing. Many methods were suggested to achieve good discrimination between different textural regions. We propose a non-supervised classification method. The method combines a multi-resolution based texture feature with features based on first and second order statistics. These features are calculated for each pixel in the image and its neighbours. A clustering algorithm, based on the generalized Lloyd algorithm, is applied and finally an iterative region merging process, based on the phagocytes heuristic, is used to improve the classification of the borders of the regions and to reduce local clustering errors. Examples of the method and the features effectiveness are presented using SPOT satellite images.

ISSN:0143-1161    

DOI:10.1080/01431169208904130

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Satellite observations over the ocean in the backscatter direction are dominated by Rayleigh scattering. We use this predictable radiance for in-flight calibration of the visible SPOT channels. Two methods are evaluated. The first method directly relates the measured numerical signal in a short wavelength channel to the predicted reflectance. In the second method, we use a second channel centred at a longer wavelength, to correct the short wavelength channel for the effect of the atmospheric aerosol contribution. These two methods are examined for channelB0, centred at 045μmplanned for launch on SPOT-4 VEGETATION, and for channelB1centred at 0-55mu;mm, currently on-board SPOT-1 HRV. In both cases, the channelB3, centred at 0-85mu;mmis used for aerosol correction. Error analysis shows that accuracies of 3 and 5 per cent respectively can be achieved for B0and B1. The last section of the paper is devoted to a validation of the error analysis using SPOT-1 HRV data.

ISSN:0143-1161    

DOI:10.1080/01431169208904131

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

It is possible to assess crop yields at the end of the growing season in a semi-arid environment using data from meteorological satellites. This is the result of a work carried out in northern Burkina Faso. The technique used is based on linear correlation between millet yield and the time integral of the Normalized Difference Vegetation Index (iNDVI) derived from NOAA AVHRR data. In contrast to earlier related studies, the correlation has been established using satellite data extracted exclusively within the agricultural domain. The integration period for the iNDVI correponds to the reproductive phase only of the growing period of millet. Furthermore, iNDVI can also be used to estimate the acreage or the agricultural domain, by the application of a suitable threshold to classify areas into agricultural and non-agricultural domains.

ISSN:0143-1161    

DOI:10.1080/01431169208904132

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The difference of vertically and horizontally polarized brightness temperatures (referred to here as the polarization difference, δT) observed at 37GHz frequency of the scanning multi-channel microwave radiometer (SMMR) on board the Nimbus-7 satellite and special sensor microwave imager (SSM/I) on board the DMSP-F8 satellite could provide useful information about land surface change within the span of these global observations, November 1978 to August 1987 for SMMR and July 1987 to present for SSM/I. The atmospheric effects on the δT are studied over two 2-5° by 2-5° regions within the Sahel and Sudan zones or Africa from January 1985 to December 1986 through radiative transfer analysis using surface temperature, atmospheric water vapour and cloud optical thickness developed under the International Satellite Cloud Climatology Project (ISCCP). The atmospheric effects are also studied using surface observations of air temperature and vapour pressure at Niamey (13-5° N, 2-2° E) for the period January 1979 to December 1990. It is found that atmospheric effects alone cannot explain the observed temporal variation of δT, although the atmosphere introduces important modulations on the observed seasonal variations of δT due to rather significant seasonal variation of precipitable water vapour. Therefore, these δT data should be corrected for atmospheric effects before any quantitative analysis of land surface change over the Sahel and Sudan zones. The entire global data set from December 1978 to December 1990 has been archived for unrestricted distribution and use.

ISSN:0143-1161    

DOI:10.1080/01431169208904133

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Airborne Daedalus DS-1260 MSS data were acquired over three water cooling reservoirs (active to inactive, large (1068 ha) to small (68-6 ha)) concurrent with field data collection to map the distribution of the water quality as related to the trophic state within each reservoir. Water characteristics, including algal pigments, total suspended particles, as well as dissolved and particulate organic matter, were obtained at 31 sites. These water quality measurements were evaluated in terms of their importance in explaining water phenomena observed by using remote sensing reflectance images. Measurements that exhibited unique variances were related to remote sensing data using a statistical methodology to identify relations explaining the greatest amount of variance for each water variable. This approach resulted in predictor equations explaining 91 per cent of the chlorophyll-a variance, 91 per cent of the total suspended particles variance, and 98 per cent of a Trophic State Index variance based on the depth of light penetration. Further, remotely-sensed thermal data explained 88 per cent of the measured surface water temperature variance. These relations were used to produce maps depicting the quantitative distribution of these water quality variables and the bulk near-surface water temperature distribution within the active water cooling reservoir. The two-water cooling reservoirs not affected by thermal inflows were characterized by water containing very low and uniform concentrations of all water property measures. Conversely, the thermally active reservoir was characterized by higher and more variable water property concentrations; there was a spatial covariation between decreases in the bulk near-surface water temperature and increases in almost all water quality indicators.

ISSN:0143-1161    

DOI:10.1080/01431169208904134

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431169208904135

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431169208928375

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431169208928376

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Initial observations on the effects of wildfires in black spruce forests on radar backscatter are presented. Airborne and spaceborne SAR imagery are utilized to illustrate two distinct fire signatures. A theory is presented to explain these differences.

ISSN:0143-1161    

DOI:10.1080/01431169208904137

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor