ISSN:0143-1161    

DOI:10.1080/01431169508954442

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Following the successful launch and operationalisation of Indian Remote Sensing Spacecraft IRS-1A and IRS-1B, the Indian Space Research Organisation has taken up the work of developing the second generation Remote Sensing Spacecraft IRS-1C/1D with improved resolution and additional spectral band. These spacecraft will provide continuity of service to the users and help develop further the application potential. IRS-1C/ID will weigh about 1200kgs with improved platform performance and will carry a panchromatic camera, a multi-spectral camera and a wide field sensor camera providing resolutions greater than 10m, 23.6m, and 188m respectively. The first of these spacecraft will be launched in 1995 and the second in 1997-98.

ISSN:0143-1161    

DOI:10.1080/01431169508954443

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A highly dynamic learning (DL) neural network is developed and applied to perform the inversion of rough surface parameters: dielectric constant, surface rms height, and correlation length, The network training scheme is based on the Kalman filter technique which lends itself to a highly dynamic and adaptive merit during the learning stage. The training data sets utilized were obtained from the Integral Equation Model (IEM) which has a wide range of frequency. The training speed of the network is found to be much faster than the back-propagation (BP) trained multi-layer preceptron (MLP) with the same degree of accuracy. When applied to invert the surface parameters, the DL network shows a very satisfactory result in terms of learning time and process accuracy which thus enhances its potential applications to remote sensing of rough surfaces.

ISSN:0143-1161    

DOI:10.1080/01431169508954444

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Regional radiometric-geological mapping of the outcropping basement complex in the Gabal Eteiqa area has been carried out through the application of factor analysis technique

ISSN:0143-1161    

DOI:10.1080/01431169508954445

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The lack of silt transported by the River Nile after the building of the Aswan High Dam in 1964 has created a serious imbalance at the Rosetta and Damietta promontories on the Mediterranean coast of the Nile delta. In this work, coastal changes of the Rosetta promontory have been monitored by analysis of aerial photographs and satellite images over the period 1955 to 1991. Principal component analysis and temporal classifications have been used to clarify the dynamics of erosion and accretion areas on the two sides of the promontory. The studies have also indicated changes in the River Nile channel itself. Comparison with ground based measurements have revealed complete agreement.

ISSN:0143-1161    

DOI:10.1080/01431169508954446

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Images are now widely available in the form of digital data. Unfortunately the amount of data that results from the digitization process is extremely large, resulting in high costs in terms of storage demand or transmission bandwidth for such data. Image data compression techniques are becoming widely used in order to reduce these problems, a standard technique being the Discrete Cosine Transform (DCT). Significant compression ratios are achievable using the DCT (typically 20:1), but with the drawback of some loss of accuracy in the decompressed reconstructed image. In some applications (e.g., videophone) some loss in the received data can be tolerated. The purpose of this paper is to present an assessment of the compression available when the DCT is applied to remote sensing images, and to determine the effects of data loss in terms of image fidelity and experimental multi-band classification of reconstructed image data. Results are presented to demonstrate the effects of using the DCT for remote sensing image data compression.

ISSN:0143-1161    

DOI:10.1080/01431169508954447

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We performed experiments to collect radar backscatter data at Ku(13.4GHz) and C bands (5.3GHz) over simulated sea ice at the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) during the 1990 and 1992 winter seasons. These experiments were conducted over bare saline ice grown in an indoor tank and an outdoor pond facility. The radar data were calibrated using a complex vector calibration scheme to reduce systematic effects. In conjunction with the radar measurements we measured ice physical properties

ISSN:0143-1161    

DOI:10.1080/01431169508954448

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Synthetic aperture radar images are generally corrupted by speckle noise. This arises due to the coherent nature of radar echoes used in the image formation and it is often necessary to enhance the image by speckle suppression before data can be used in various applications. To suppress speckle and improve the radar image interpretability a simple filtering technique has been proposed. The filter is adaptive to the variance of pixel intensity in a sliding window and accordingly decides the number of nearest neighbours to the central pixel to replace its intensity with the average intensity of those nearest neighbours. The performance of the filter has been studied for speckle removal in the homogeneous areas and its edge retention capability and compared with some of the widely known speckle filters. The results show that the proposed filter retains edges, removes speckle noise and compares well with other known filters in the literature.

ISSN:0143-1161    

DOI:10.1080/01431169508954449

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

To characterize scatterometer returns from the sea surface near meteorological fronts, we investigated microwave scattering from seas in which long waves are at oblique angles to short waves. We simulate the effects of veering winds onC-andKu-band scatterometers by using models in which the short waves align with the wind friction velocityu*, but the long waves are at oblique angles to theu*direction. The analysis reveals two main effects due to the rotation of the long wave slope probability density distribution. Azimuthally averaged normalized radar cross-sectionaodecreases as the oblique angle increases. Additionally, two regimes exist. In the small angle regime, azimuthal scans of normalized radar cross-section σoexhibit features similar to the classic double-maxima pattern for non-veering wind conditions, but the axis of σomaxima is rotated toward the long-wave axis. In the large angle regime, more than two maxima are apparent in azimuthal scans. Therefore it may be inappropriate to use standard three term Fourier cosine models for some veering wind conditions.

ISSN:0143-1161    

DOI:10.1080/01431169508954450

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Study of the Earth's terrestrial ice masses (glaciers, ice caps and ice sheets), especially the seasonal variation of different surface conditions such as dry snow, wet snow and bare ice, is of particular importance in relation to possible climatic change. Synoptic monitoring techniques using visible and near-infrared satellite imagery are severely limited by the prevalence of cloud cover in the polar regions, and winter observations are impossible as a result of the absence of solar radiation. Consequently, considerable attention is now being focused on the use of imaging radar in the study of large ice masses. In this paper, we present and interpret a time-series of C-band synthetic aperture radar images acquired using the ERS-1 satellite from the Austfonna ice cap in eastern Svalbard. Winter imagery shows little variability, most of the ice cap having a uniform and high (approximately – 3dB) backscatter attributed to ice lenses or to a large effective grain size. Summer imagery shows considerable topographically-related detail, and backscatter values typically 5 to l0 dB less than in winter, which can be explained on the basis of surface scattering from wet snow. However, the marginal areas of the ice cap show a clearly defined zone of high ( –5dB) backscatter in mid- to late-August. It is proposed that this corresponds to the bare ice zone, the high backscatter values being due to scattering from crevasses and meltwater channels, and that the inner boundary of the zone of enhanced backscatter indicates the position of the transient snow line.

ISSN:0143-1161    

DOI:10.1080/01431169508954451

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor