摘要:

The purpose of the studv was to explore the information available in a multi-temporal Synthetic Aperture Radar (SAR) data set covering a full seasonal cycle, and to identify issues that must be considered in conducting further research in this area. The data set was compiled from images obtained using the C-band SAR of the Canada Centre for Remote Sensing over a test flight line near Ottawa. All SAR images were geometrically corrected, registered to a UTM projection and resamplcd to 6-25 m pixels. A fall Landsat Thematic Mapper image was also resampled and co-registered with the SAR images. A procedure was developed to display differences between SAR images taken at successive dates. Both individual and difference SAR images were analysed with reference to ground and hydrome-teorological data acquired from various sources. Results of the analysis indicate that SAR images obtained over the annual cycle contain information on the dynamic behaviour of various land surface cover types. Variations were most pervasive in the case of vegetation and secondly in the case of surface water, including vegetation-water interactions. The results also highlighted the requirement of precise geometrical registration, calibrated (relatively or better) SAR and-accurate hydrometeorological data (including within site variability) within the site to detect and analyse changes in SAR images.

ISSN:0143-1161    

DOI:10.1080/01431169208904045

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A technique for estimating crop coverage using linear mixture modelling of multi-temporal Advanced Very High Resolution Radiometer (AVHRR) data is presented for a study area in northern Greece. This paper identifies some of the problems associated with using satellite sensor data with coarse spatial resolution for crop area estimation. Using satellite sensor imagery with a high spatial resolution to extrapolate ground measurements to AVHRR scales, the paper shows how the mixture model can be applied to AVHRR data in a mixed agricultural system. Crop areas are estimated to an average accuracy of 89 percent on regional scale using this technique. The results show that this linear mixture modelling has potential for operational crop area monitoring on a regional basis.

ISSN:0143-1161    

DOI:10.1080/01431169208904046

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Studies for estimating cultivated area and yield of rice using remote sensing data acquired from the Landsat Thematic Mapper (TM) system with six bands (1, 2, 3,4, 5,7) were conducted. Three images taken on different days were visually and digitally analysed for the estimation of rice cultivated area. This was obtained with over 90 per cent classification accuracy. False colour composite of 5R, 4G, 3B was selected for the identification of rice cultivated area at maturity stage. Band combination of 1, 3, 4 and 5 was selected as an appropriate subset in the digital analysis for the estimation of rice areas. An attempt was made to develop a relationship between reflectance values and actual grain yield using an image of the fully ripened stage of the crop. High correlation was observed with reflectance values of some bands and yields. A computerized plant process model was adopted for the simulation of rice growth and yield. This was used for estimating yield per unit area.

ISSN:0143-1161    

DOI:10.1080/01431169208904047

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Stereoscopic interpretation of colour infrared (CIR) aerial photographs and analysis of SPOT multispectral (XS) data offer alternative methods for the documentation of land cover change of the Causse du Larzac, of a heathland region in the southern part of the Massif Central, France. Discussion of multitem-poral classification results leads to an advanced understanding of the value of visual and/or computer-related image interpretation of seminatural environments. Analysis of in situ measurements of spectral reflectance properties of classified land cover types completes the investigation of remotely sensed heathland monitoring.

ISSN:0143-1161    

DOI:10.1080/01431169208904048

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Laboratory measurements of the spectral reflectance of leaves from a variety of species were made over the 400-2500 nm range using a spectroradiomctcr. The relation between spectral reflectance and leaf water content was investigated and the effect of differences in leaf structure were found to be important. The first derivative of the reflectance spectrum, at wavelengths corresponding to the slopes on the edges of the water absorption bands, was found to be highly correlated with leaf water content and insensitive to differences in leaf structure.

ISSN:0143-1161    

DOI:10.1080/01431169208904049

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Experimental flight measurements were carried out in Hungary on 14 October 1988 to check the performance of the airborne microwave L-band radiometer system developed by the Space Research Group, Technical University of Budapest, for the determination of soil moisture. The results of the aircraft measurements at two different altitudes are presented. The relation between soil moisture and emissivity predicted by different dielectric models are used to estimate soil moisture. The estimated soil moisture is compared with limited ground truth soil moisture taken synchronously with flight measurements. Soil moisture and topographic maps are presented for quick-look observation of soil moisture against agricultural fields.

ISSN:0143-1161    

DOI:10.1080/01431169208904050

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Distributed hydrological and ecological models on a local scale require information of the spatial distribution of the soil water content. The usefulness of different airborne imaging passive and active microwave sensors in obtaining soil moisture data is investigated. An experimental imaging 90 GHz radiometer, an X-band SLAR and an L-band SAR gathered data over two areas in Northern Germany. The radiometer- and radar-images of selected bare fields are studied with respect to the sensitivity to soil water content of the used sensors. Linear regression analyses between backscatter values and soil water content are performed for single measurement points. The X-band SLAR is found to give the best results. But speckle and ambiguities of the radar signature due to roughness and vegetation cover impede the application of the regression equation to the complete catchment. Thus, the investigated sensors are still limited as input sources to distributed hydrological models of complex areas.

ISSN:0143-1161    

DOI:10.1080/01431169208904051

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

AgriSAR 86 data from the Feltwell Site, U.K., was affected by a variety of radiometric distortions. These distortions prevent accurate calibration of the images, but analysis of the image statistics, after some radiometric corrections have been performed, permits a number of qualitative inferences about variations in crop backscatter in time and space. Cereals and sugar beet appear to exhibit different incidence angle responses. The separability of wheat and sugar beet varies with time and incidence angle. The separation of spring barley and wheat varies with time. Cereals show greater spatial variability than sugar beet. Individual fields exhibit great apparent variability in their temporal responses; for sugar beet this can in the main be explained by the effects of speckle, but there is some evidence of real variation for winter wheat.

ISSN:0143-1161    

DOI:10.1080/01431169208904052

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper describes a simple, computationally inexpensive procedure for automatically identifying coastal features in an unnotified, unregistered daytime image. The procedure can be used to identify ground control points for image registration and to provide a local correction for the navigation predicted from the satellite orbit parameters supplied in the T-bus transmission. The correction consists of a horizontal displacement and a rotation, the latter accounting for errors in the roll, pitch and yaw of the satellite platform.

ISSN:0143-1161    

DOI:10.1080/01431169208904053

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The study of multitemporal data needs geometric registration of each image with a standard master image. The role is described of a narrower distribution of ground control points in the across-track direction with respect to the area of interest in minimizing the registration error. The 1·1 km spatial resolution of the Advanced Very High Resolution Radiometer (AVHRR) onboard the National Oceanic and Atmospheric Administration (NOAA) meteorological satellites has contributions from varying degree of vegetation characteristics within the pixel dimensions. The contrast among the vegetated, less intensely vegetated and non-vegetated pixels are enhanced in the Normalized Difference Vegetation Index (NDVI) image due to the use of a very high gain factor in converting the observed range of NDVI values to 8-bit scale. Also discussed is the radiometric misrepresentation in the grey values of new pixels created by geometrical correction applied directly to a vegetation index image.

ISSN:0143-1161    

DOI:10.1080/01431169208904054

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor