摘要:

The process is a completely closed system employing only image data, and it can be applied to any digital multi-spectral data set. A computer technique has been developed to produce spectral reflectance images from multi-spectral images. Hue, intensity and saturation (HIS) colour spatial transformation is used to compute the hue of a three-band colour composite image, and the image pixels with the same hue value are taken as a single material. The average brightness values of the pixels with the same hue are calculated for each band separately, and the distribution of the average values is taken as spectral reflectance image. This spectral reflectance image, which is essentially free of topographic modulation function, but includes spectral information, can be used in image classification, or other image processing. This technique has been successfully applied to recognize ore bearing rock in Inner Mongolia, China by Landsat TM images. The HIS transformation model is a new, very simple and practical technique. It is potentially useful for extracting spectral reflectance information and suppressing the terrain effect.

ISSN:0143-1161    

DOI:10.1080/01431169608949163

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

An image-based retrieval algorithm of aerosol characteristics and surface reflectance for satellite images is proposed. By assuming the Junge size distributed aerosol in the atmosphere and feeding back the new Junge parameter, not only the aerosol optical depth but also the Junge parameter, single-scattering albedo and phase function can be iteratively derived and converged from digital counts of dense dark vegetation in the green and red bands of SPOT satellite image. These retrieved aerosol characteristics are considered to be more physically related to the image itself than estimated. To prevent over-estimating aerosol optical depth, multiple scattering of path radiance for aerosol is taken into consideration. Although in lack of field measurement, the algorithm is evaluated and proved to be useful by simulation. Its sensitivities to assumed dense dark vegetation reflectances, log-normal size distribution, initial assumed power of Junge size distribution, refractive index and radius range are also studied. The retrieved aerosol optical characteristics are further used to derive surface reflectance of SPOT satellite image by a proposed atmospheric correction model for non-uniform and Lambertian surface. Without atmospheric correction, the RMSE between the apparent and field-measured reflectance is 0·076 for reflectance range 0·0 to 0·6. The RMSE between the derived and field-measured reflectance is greatly reduced to 0·022, if the image is atmospheric-corrected.

ISSN:0143-1161    

DOI:10.1080/01431169608949164

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A recent comment from Gordon and Evans took issue with two aspects of the analysis of Coastal Zone Color Scanner (CZCS) pigment extraction algorithms. This reply refuted the arguments of Gordon and Evans. The multiple Rayleigh scattering algorithm does not always make physical sense, nor has the physical validity of Ångström's coefficient been established as a means of parameterizing the aerosol scale factor. We also disagreed with the position put forward by Gordon and Evans that the artifacts in the CZCS data will disappear in the next generation sensor (SeaWiFS) because the problem of quantifying the aerosol contribution from these satellite measurements has not yet been solved to sufficient accuracy. Finally, these factors, coupled with electronic overshoot and the decay of the CZCS sensor's sensitivity over time, make it unlikely that the quality of derived pigment values will be significantly improved by reprocessing the CZCS archive yet one more time as suggested by Gordon and Evans.

ISSN:0143-1161    

DOI:10.1080/01431169608949165

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The ability of space technology to provide basic information in space, time and frequency domains has been proved to be very useful in providing permanent records by mapping, monitoring and managing flood dynamics. In July 1993, floods were at their devastating worst in Punjab (India) for the second time since September 1988. In this study, IRS 1A LISS-I false colour composites and ERS panchromatic images were used to obtain near real time information on damage due to floods in July 1993. The flood map of September 1988 was also used to monitor the flood damage. The flood maps for the year 1988 and 1993 were superimposed to prepare a combined map on a 1:500 000 scale to extract and demarcate flood prone areas in Punjab (India). This study suggests that during 1988, the flooding was mainly due to overflowing of rivers, whereas in 1993 it was due to breaches in embankment of rivers and canals.

ISSN:0143-1161    

DOI:10.1080/01431169608949166

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Classification of JERS-1 (Fuyo-1) SAR data from the northwestern portion of Brazil was performed using the semivariogram textural classifier (STC). This is a deterministic, supervised classifier which provides the option of combining textural and radiometric information. Textural information is expressed by the semivariogram function; radiometric information is conveyed by the mean digital number (DN) value. Results have shown that STC allows vegetation units and water bodies to be discriminated and tentatively mapped, suggesting that this is a promising approach for environmental monitoring of rainforest regions using SAR data.

ISSN:0143-1161    

DOI:10.1080/01431169608949167

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Research on the application of coarse spatial resolution imagery has focused on the potential of the Normalized Difference Vegetation Index (NDVI) and similar indices to identify and map land cover al a regional scale. The ready availability of Advanced Very High Resolution Radiometer (AVHRR) data has allowed the development of methods which observe the change in spectral character of specific ground locations over time through the pattern of the temporal NDVI profile. This letter describes a method of analysing NDVI temporal profiles using a similarity measure which is commonly available in pattern analysis packages. This method is applied in an agricultural and forested context.

ISSN:0143-1161    

DOI:10.1080/01431169608949168

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor