摘要:

Abstract. This paper introduces a very simple method to achieve a saturation (decorrelation) stretch without coordinate transformation, the Direct Decorrelation Stretch (DDS) technique. In RGB (red, green and blu) colour coordinate space, a colour vector can be expressed in terms of an achromatic component and a chromatic (pure colour) component. A direct decorrelation stretch of a RGB colour image is achieved by decreasing the magnitude of the achromatic component of the colour vector for the pixel being processed. Initially, the R, G, and B digital numbers (DNs) for each colour pixel are examined and the lowest value (it could be the red, green or blue) is selected. A fixed ( user controlled) proportion of the selected lowest DN is then subtracted from each of the original R, G and B DNs of this pixel. The result of the subtraction, based on RGB pixel minimum values, is an image with reduced achromaeity. This corresponds to increased saturation.

ISSN:0143-1161    

DOI:10.1080/01431169608949060

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Satellite data can provide valuable information on the spatial and temporal variability of sea ice. Ice concentrations can be derived from passive microwave data such as from the SSM/ I (Special Sensor Microwave/ lmager). These data have been used to study the annual variations in the ice-edge, especially in the timing and form of the ‘ Odden’ feature. The Odden is a tongue of sea ice which forms over the cold Polar Water of the Jan Mayen Polar Current as it is forced north-eastwards by the North Jan Mayen Ridge. In the winter months the Odden dominates the Greenland Sea extending over 1000 km from the coast. Daily monitoring of the SSM/ 1 ice concentrations in February 1988 showed that the Odden could vary up to 350 km in length in a 24-hour period. This is due to the rapid formation of pancake ice and not to movement of the existing ice.

ISSN:0143-1161    

DOI:10.1080/01431169608949061

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Abstract This paper compares estimates of the signal-to-noise ratio(SNR) required by imaging spectrometers for the estimation of foliar biochemical concentrations and the SNR currently achieved by the Airborne Visible/ Infrared Imaging Spectrometer (AVIRIS). The work was comprised of three sections. Section 1: the SNR required by imaging spectrometers was estimated by modelling three data sets, each of which more closely approximated the data recorded by the AVIRIS. The remaining stages were concerned with estimating the SNR currently achieved by the AVIRIS. Section 2: SNR estimates made as part of instrument calibration were scaled to those that would be expected when viewing vegetation, and section 3: SNR was estimated directly from AVIRIS imagery. The results of these three sections were then compared to assess the SNR performance of the AVIRIS and its utility for the estimation of foliar biochemical concentrations. The SNR of the AVIRIS is planned to double between 1994-5 and while this sensor was barely adequate for the estimation of foliar biochemical concentrations in 1992-3 it should be more than adequate from 1995 onwards.

ISSN:0143-1161    

DOI:10.1080/01431169608949062

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431169608949063

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431169608949065

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431169608949066

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The Gamma-Gamma Maximum a posteriori filter provides an estimate of the speckle-free radar cross-section when both the radar reflectivity and the speckle distributions are gamma-distributed. In this Letter, it is shown that a factor greater than two in precision can be typically gained in the radar cross-section estimate in the case of natural land Synthetic Aperture Radar (SAR) clutters. This is accomplished by using the normalized logarithmic estimator which is a more accurate index than the coefficient of variation to deduce the local heterogeneity parameter.

ISSN:0143-1161    

DOI:10.1080/01431169608949067

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The 1-6 ^m channel of the Along Track Scanning Radiometer-1 (ATSR-1) does not benefit from a pre-launch or onboard digital count to spectral radiance calibration mechanism. This Letter outlines the results of a post-launch calibration procedure, accomplished by comparing near-coincident data from the uncalibrated ATSR-1 instrument onboard ERS-1 and the (calibrated) OPS instrument onboard JERS-1. These results show that the ATSR-1 1-6(im channel can be considered linear in response to incoming radiance and equations are produced that allow data from this channel to be calibrated in units of spectral radiance and/ or spectral reflectance.

ISSN:0143-1161    

DOI:10.1080/01431169608949068

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Classification trees are a powerful alternative to more traditional approaches of land cover classification. Trees provide a hierarchical and nonlinear classification method and are suited to handling non-parametric training data as well as categorical or missing data. By revealing the predictive hierarchical structure of the independent variables, the tree allows for great flexibility in data analysis and interpretation. In this Letter, we compare a tree' s performance to that of a maximum likelihood classifier using a 1° by 1° global data sel. The tree's accuracy in classifying a validation dala set is comparable to that when using maximum likelihood (82 per cent). The tree also may be used to reduce the dimensionality of data sets and to find those metrics that are most useful for discriminating among cover types.

ISSN:0143-1161    

DOI:10.1080/01431169608949069

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This Letter presents an adapiive contexiual filler, developed by Ihe addition of a heterogeneity rule and a confidence rule to The conventional majority filter. Experiments have been carried out using a Landsat Thematic Mapper (TM) image. Results show that the adaptive majority filter has a capability of reducing the classification errors due to spectrally mixed pixels and preserves The connection of thin features. The proposed filler needs only a moderate increase in processing time compared with the conventional majority filter.

ISSN:0143-1161    

DOI:10.1080/01431169608949070

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor