ISSN:0143-1161    

DOI:10.1080/01431169208904060

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper describes a method to produce a relative digital elevation model (DEM) from SPOT level 1A stereo pair or triplet images without the use of ground control points. The proposed method consists of 1. stereo matching by correlation, 2. calculation of the intersection point of pair or triplet viewing lines and 3. interpolation from random DEM to grid DEM. The emphasis is laid on how to restrict a search area for stereo matching using approximate epipolar constraint.

ISSN:0143-1161    

DOI:10.1080/01431169208904061

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

One of the more efficient methods used for in-flight calibration of Earth resource satellites is based on measurements performed at ground level on a test site. An experimental study has been conducted in La Crau Sèche (south east France), where a calibration site for SPOT satellites is intended. The accuracy of the calibration depends, critically, on the accuracy of ground bidirectional reflectance factor (BDRF) measurements.

ISSN:0143-1161    

DOI:10.1080/01431169208904062

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

High resolution spectral measurements of reflectance and transmittance of leaves ofVicia faba L. exposed to sulphur dioxide were taken using an integrating sphere. Changes in detailed spectral-curve shape, found by analysing spectral first derivatives, were caused by exposure to sulphur dioxide concentrations between 200nl1−1and 800 nl1−1for ten day periods. Analysis of spectral derivatives may provide a quantitative method for specific remote identification of plant stress induced by sulphur dioxide in the field. The spectral effects of sulphur dioxide on leaves are examined in relation to leaf structural properties and pigments.

ISSN:0143-1161    

DOI:10.1080/01431169208904063

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In recent years, remote sensing and crop growth simulation models have become increasingly recognized as potential tools for growth monitoring and yield estimation of agricultural crops. In this paper, a methodology is developed to link remote sensing data with a crop growth model for monitoring crop growth and development. The Cloud equations for radar backscattering and the optical canopy radiation model EXTRAD were linked to the crop growth simulation model SUCROS: SUCROS-Cloud-EXTRAD. This combined model was initialized and re-parameterized to fitsimulatedX-band radar backscattering and/or optical reflectance values, tomeasuredvalues. The developed methodology was applied for sugar beet. The simulated canopy biomass after initialization and re-parameterization was compared with simulated canopy biomass with SUCROS using standard input, and with measured biomass in the field, for 11 fields in different years and different locations. The seasonal-average error in simulated canopy biomass was smaller with the initialized and re-parameterized model (225-475 kg ha−1), than with SUCROS using standard input (390-700 kg ha−1), with ‘end-of-season’ canopy biomass values between 5500 and 7000kgha−1. X-band radar backscattering and optical reflectance data were very effective in the initialization of SUCROS. The radar backscattering data further adjusted SUCROS only during early crop growth (exponential growth), whereas optical data still adjusted SUCROS until late in the growing season (at high levels of leaf area index (LAI), 3-5).

ISSN:0143-1161    

DOI:10.1080/01431169208904064

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Landsat Thematic Mapper data are utilized to improve upon the ground yield survey estimates for wheat in India. The normalized difference and ratio vegetation indices computed from the spectral responses are used to obtain homogeneous vegetation vigour stratifications of the cropland of the study area. Certain post-stratified estimators that make use of these stratifications are investigated and are shown to provide improved crop yield estimates.

ISSN:0143-1161    

DOI:10.1080/01431169208904065

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

High-spectral-resolution reflectance spectra from ground and helicopter measurements of agricultural crops and soils were analyzed to determine spectral variability in the visible and near-infrared (0 4-2 38 μm), using a procedure previously applied to thermal infrared emittance spectra of the atmosphere and to reflectance spectra of soil samples. Five spectral basis functions were sufficient to describe separately the ground and helicopter data, six or, at most, seven are sufficient to describe the pooled data. Thus, five to seven relatively broad band measurements, together with basis functions developed in this analysis, are sufficient to describe the variability of both data sets, to within differences that are probably associated with the measurement process and instrument noise.

ISSN:0143-1161    

DOI:10.1080/01431169208904066

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Upwelling radiance from pure cultures and natural populations of freshwater algae is examined. The effects of changes in the vertical distribution of the algae on the upwelling radiance are also explored. The different algae studied were spectrally very similar. The volume reflectance for any given chlorophyll concentration differed between the Phyla studied. This appeared to be due to the colonial nature of some species. Higher chlorophyll concentrations resulted in higher reflectance in all but the blue wavelengths, and correlations between reflectance in the near-infrared andLnlorophyll were the highest. This suggests that remote sensing of algae in inland waters should be based on increased scattering by the cells and not increased absorbtion by chlorophyll.

ISSN:0143-1161    

DOI:10.1080/01431169208904067

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper provides an analysis, together with simulation, of the accuracy with which the quadratic focus parameter used in generating SAR images can be obtained. Previous analyses expressed the error in this quantity in terms of a depth-of-focus measure. We demonstrate that considerably greater accuracy can be achieved under certain conditions. We derive the predicted error in this parameter for a point target on a weak background and also introduce the effect of extended random targets within the scene.

ISSN:0143-1161    

DOI:10.1080/01431169208904068

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Models for underwater acoustic properties depend heavily on the windspeed and other relevant geophysical parameters. At sea such parameters will in the future increasingly be provided by satellite radars. The NARSHA (NATO Remote Sensing SHAllow water) experiment was designed to investigate the relationship between observations from satellite, airborne, and surface radars on the one hand, and acoustic observations of propagation loss, reverberation, and ambient noise on the other. Radar returns from the sea result from mechanisms comparable to those which generate sea stale noise and absorb and scatter underwater sound. The experiment demonstrated the existence of a relation between these quantities. Further investigation is necessary to indicate how reliably the effects of the interfering boundary layer on the wind can be circumvented by interrelating radar and acoustic quantities directly and to validate these relations statistically.

ISSN:0143-1161    

DOI:10.1080/01431169208904069

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor