ISSN:0143-1161    

DOI:10.1080/01431169108955232

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The overall goal of the research is to develop a robust extraction technique for inferring physical and biological surface properties of vegetation using nadir and/or directional reflectance data as input. A prototype knowledge-based expert system VEG is described that concentrates on extracting spectral hemispherical reflectance using any combination of nadir and/or directional reflectance data as input. VEG is designed to facilitate expansion to handle other inferences regarding vegetation properties such as total hemispherical reflectance, per cent ground cover, leaf area index, biomass, and photosynthetic capacity. This approach is more accurate and robust than conventional extraction techniques developed by the investigator and others. VEG combines methods from remote sensing and Artificial Intelligence (AI), It integrates input spectral measurements with diverse knowledge bases available from the literature, data sets of directional reflectance measurements, and from experts, into an intelligent and efficient system for making vegetation inferences.

ISSN:0143-1161    

DOI:10.1080/01431169108955233

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Relations between radiative surface temperature (TR) and visible and near-infrared reflectances expressed as the normalized difference (ND) from a Landsat Thematic Mapper scene were analysed to study the heat balance of agriculture and native evergreen forests in southeastern Australia. The scene was at 0922 h (local time) during late spring (15 October 1986) with phenology of winter annual species between flowering and grain filling. Factors determining the slope of, and residual scatter about, the TR)/ND relationships were analysed using a coupled two-layer soil-vegetation model of the surface heat balance. Inverse linear relationships were found between TR), and ND for agriculture, but not for forests. This was a result of a wide range of ND and TR) values in agricultural areas caused by wide variations in fractional vegetation cover. The relationships between ND and fractional vegetation cover was not general, thus, when forest and agricultural data were combined, the lower near-infrared reflectance of forests (16-9 per cent) compared with agricultural crops (29-0 per cent) resulted in forest data falling below the regression line for agriculture. From the agricultural relations, 60 to 70 per cent of the variation in TR) was explained by ND, indicating that fractional vegetation cover was the dominant factor determining TR). Residual variability of TR) was attributed to spatial variability in ambient temperature, rates of soil evaporation and variations in stage of phenological development affecting stoma-tal resistance. Energy-balance analysis of the effect of soil water availability on the slope of theR)‘ND relationship indicated opposite effects depending on whether the reduction in evaporation was from soil or from vegetation. Thus, the generality of using the slope of the TR)/ND relationship to predict surface resistance to evaporation may be limited. It was concluded that extraction of information contained in TR) and ND data for regional estimation of evaporation requires the separation of TR) into soil and vegetation temperatures and an alternative to ND that relates more generally to fractional vegetation cover.

ISSN:0143-1161    

DOI:10.1080/01431169108955234

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This study reports on an investigation of multi-date water-quality calibration algorithms under turbid inland water conditions using Landsat Thematic Mapper (TM) multispectral digital data. TM data and water-quality observations were obtained near-simultaneously in Green Bay, an embayment of Lake Michigan, and related using linear regression techniques. The high concentrations of terrestrially-derived suspended solids appear to be controlling the water volume reflectance. A simple exponential model using the band 3/band 1 (0-660μm/0-485μm) ratio was found to be a useful index for estimating total suspended solids and water transparency (i.e. Secchi disk depth) with an accuracy of ± 25 per cent over the calibration data range.

ISSN:0143-1161    

DOI:10.1080/01431169108955235

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Image-processing systems based on microcomputers are now widely available. At the same time, interest in processing archived Coastal Zone Color Scanner (CZCS) data continues to grow. However, procedures for obtaining chlorophyll estimates from CZCS raw counts often make extensive use of trigonometric and exponential functions and are computationally expensive. The algorithm outlined here uses spline interpolation, ‘look-up’ tables and a mathematical transformation to implement accurately a chlorophyll-estimation procedure while reducing the computational load to a level appropriate to microcomputers. This algorithm may also be of interest to those planning real-time processing of global data sets from future ocean-colour scanners.

ISSN:0143-1161    

DOI:10.1080/01431169108955236

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In situmeasurements of water quality, collected by two ships and a helicopter, and remotely sensed data provided by a Daedalus Airborne Thematic Mapper have been compared in order to generate a calibration algorithm for Chlorophyll-a in the Bristol Channel off the South Gower Coastline. Statistical analyses showed that pigment concentration can be retrieved from the received radiances at channels 1 (0-42-0-45 μm), 3 (0- 52-0-60 μm) and 5 (0-673-0-69 μm), despite the high tidal stress in the area. Comparisons are made between the algorithm and previous ocean-colour experiments. It is concluded that, although the acuracy of determining Chtorophyll-a concentration in this case is lower, there is a great similarity between the slopes in a logarithmic form. Valuable information about the variability of Chlorophyll-a over a tidal cycle was obtained by airborne remote sensing, demonstrating its feasibility for monitoring water quality parameters.

ISSN:0143-1161    

DOI:10.1080/01431169108955237

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

We have developed a method to analyse SPOT imagery for oil exploration. This method is assessed in an area located in southeastern France, a region already associated with such activity. After standard processing of SPOT data, a 1:200 000 scale overall analysis is made on a mosaic of the different images. This is followed by a detailed analysis at the same scale. A more detailed analysis at 1:100000 scale, taking into account all the pre-existing data that are compiled comparatively with the imagery, results in a synthetic geological map. Systematic exploitation of SPOT stereoscopy, good ground resolution and more specialized processing techniques permitted the discovery of large or detailed structures that were unknown in this area. From this new and rapid geological mapping, geological cross-sections were drawn and afterwards compared with seismic profiling records. Many important results and interpretations concerning the subsurface structures and petroleum exploration problems were obtained: pattern of the fracturing, basin and fault inversion, evaluation of the cover detachment, amount of strike-slip movements, geometry of the Faisceau Cevenol formation of Oligocene grabens. These results assess the efficiency of the methodology used.

ISSN:0143-1161    

DOI:10.1080/01431169108955238

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The Pleistocene ridges south-west of Alexandria are of marine origin and represent the ancient shoreline of the former sea levels. Several authors have described the nature, origin and geomorphology of the Pleistocene ridges. The objective is to delineate these ridges using aerial photomosaics at 1:100000 scale and a Landsat image at 1:250000 scale.

ISSN:0143-1161    

DOI:10.1080/01431169108955239

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In polar and mid- to high-latitude regions, snow accumulates every year which covers the Earth's surface. In order to carry out geophysical work in such regions, prior knowledge of snow thickness is essential. In the present paper, the emitted brightness temperature based on an incoherent approach has been calculated for various two-layered snowpack models representative of the snow-covered terrains. The effect of snow surface roughness caused by local winds and snow melting on passive microwave remote-sensing response has also been studied. The comparison of theoretically calculated brightness temperature with the measured data shows good agreement. The results presented in this paper will be useful in the analysis and interpretation of microwave remote-sensing data of snow-covered terrains.

ISSN:0143-1161    

DOI:10.1080/01431169108955240

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Colour bias is one major cause of poor colour composite images. To eliminate this, the three bands used for colour composition must have an equal value range and mean. The balance contrast enhancement technique (BCET) is a simple solution for this problem. Using a parabolic or cubic function defined by three coefficients, BCET can stretch (or compress) images exactly to a value range and mean given by a user without changing the basic shapes of the image histograms. The FORTRAN program of BCET using parabolic (BCETP) and cubic (BCETC) functions have been developed. As colour bias is completely avoided and the full value range of the display system is properly used, high-quality colour composites as well as black and white single-band images are produced by BCET.

ISSN:0143-1161    

DOI:10.1080/01431169108955241

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor