ISSN:0143-1161    

DOI:10.1080/01431168508948419

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

In this paper, factors controlling the radiance incident on a remote-sensing device and the interaction of the sensor with upwelling radiance are considered. We also discuss systematic and random radiance variations across an image: while the former may be corrected for (to an extent) the latter may not, so that it is necessary to be aware of the impact of random variations on target identification, discrimination and quantification. Both the optical reflective and the thermal-infrared parts of the spectrum are considered. Equations are presented to concisely illustrate the processes involved

ISSN:0143-1161    

DOI:10.1080/01431168508948420

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Many polar-orbiting satellites used in high-latitude work employ instruments which sense only narrow regions of the solar spectrum. A radiative transfer scheme is used to illustrate the differences between broad-band albedos and those calculated using the spectral response of the NOAA-6 AVHRR channel 1 and DMSP visible sensors. The albedo contrast between snow/no snow is shown to be exaggerated by the satellite sensors and the impact of cloudiness over snow on the albedo is drastically reduced, by a factor of 10 in the case of the NOAA-6 sensor. A significant solar zenith angle dependence is also shown for the NOAA-6 sensor

ISSN:0143-1161    

DOI:10.1080/01431168508948421

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A literature survey of the use of data from the TIROS-N series of polar orbiting meteorological satellites in investigations outside the meteorological and oceanographic context is presented. Studies of the land surface using sensors aboard these satellites have mostly used combinations of reflected wavelengths up to the present. These studies suggest that the Advanced Very High Resolution Radiometer (AVHRR) can provide valuable information on various surface features. Comparisons of data from the TIROS-N series platforms with data from LANDSAT lend support to this view. A review of previous work outlining differences between the TIROS-N and LANDSAT satellite systems is presented together with a summary of the various combinations of reflected wavelengths as applied to land surface studies. The final section summarizes the work undertaken in studies published

ISSN:0143-1161    

DOI:10.1080/01431168508948422

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The capabilities of the Advanced Very-High-Resolution Radiometer (AVHRR) for land-cover mapping were investigated by comparing the accuracy of land-cover information for the Washington, D.C. area derived from NOAA-7 AVHRR data with that from LANDSAT Multispectral Scanner Subsystem (MSS)s data. Unsupervised level I land-cover classifications were performed for MSS and AVHRR data sets collected on 11 July 1981. A detailed accuracy assessment was conducted based on ground data delineated on 12 U.S. Geological Survey 7·5 min series topographic maps. These results produced overall land-cover classification accuracies of 71·9 and 76·8 per cent for AVHRR and MSS, respectively. While the accuracies for predominant categories were similar for both sensors, land-cover discrimination for less commonly occurring and/or spatially heterogeneous categories was improved with the MSS data set. The AVHRR, however, performed as well as or better than the MSS in classifying large homogeneous areas. The application of AVHRR data with its lower processing cost and more frequent worldwide coverage appears promising for regional land-cover mapping.

ISSN:0143-1161    

DOI:10.1080/01431168508948423

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Data from the LANDSAT and NOAA polar orbiting satellites are used to analyse the Lake Chad basin in Africa. AVHRR measurements spanning the November 1981-November 1982 period are used to monitor lake boundaries, vegetation growth and surface temperature patterns. Historical LANDSAT data from the 1972-1981 period are studied to track changes in lake and basin boundaries. Observations of lake conditions, as viewed from satellites, are related to the recent climate record

ISSN:0143-1161    

DOI:10.1080/01431168508948424

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Previous investigations have successfully used the 1·65/2·22μm ratio to map the concentration of hydroxyl-bearing minerals in imagery of sparsely vegetated terrain. However, difficulties arise in applying this ratio to semiarid regions where there is a wide variation in vegetation density. Besides mapping the mineralogic features of interest, the 1·65/2·22μm ratio also maps the density of vegetation by responding to leaf water content. A technique has been developed to estimate the vegetation contribution to this ratio based on the near-IR/red ratio. The technique has proved useful in mapping supergene alteration in the Virginia Range, Nevada

ISSN:0143-1161    

DOI:10.1080/01431168508948425

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A comparative study of soil maps prepared for part of the Anantapur District (southern India), using panchromatic black-and-white and false-colour airphotographs and airborne Modular Multispectral Scanner (M2S) data, has revealed that a better soil map in terms of soilscape boundary delineation can be prepared from false-colour airphotographs with less field checking compared with black-and-white airphotographs. M2S data offers certain advantages over false-colour airphotographs in respect of soilscape boundary delineation. However, it suffers from the limitation of grouping the picture elements with similar spectral response into one category, even if they represent two different categories on the ground. An accuracy as high as 96·4 per cent was achieved from colour infrared airphotographs as against 95·5 and 78 per cent from black-and-white airphotographs and M2S data, respectively. Nevertheless, soil maps prepared from these databases have been found to be better than a conventional soil map on the same scale

ISSN:0143-1161    

DOI:10.1080/01431168508948426

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A pulsed near-infrared laser system was converted to determine laser height and reflection values in airborne operations. The laser produces precise traces of the terrain and vegetation canopy and tree measurements can readily be made in open forests since the laser beam frequently penetrates openings in the canopy cover. The reflection measurements were useful in discriminating between vegetation type and density. Using the combined laser height, laser reflection and reflection variability parameters, it was possible to arrive at a simple semiautomated terrain classification which allowed a distinction between conifer and broadleaf forests and terrain with low-growing vegetation cover. The classification of individual trees into coniferous and broadleaf of different height classes is demonstrated. The data is in digital form and can be incorporated into geographic information systems. Considering that these measurements were made at a single wavelength (904 nm), it is clearly evident that high-resolution vegetation surveys are possible in the near future using multiple or tunable lasers

ISSN:0143-1161    

DOI:10.1080/01431168508948427

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

This paper describes a method of measuring water depths using a hybrid airborne sensor which incorporates both a lidar system and a passive multispectral scanner system. The methods of processing the data collected by this sensor are described and results are presented for data from two test sites in the Bahama Islands. Errors in the depth measurement are quantified, and an analysis of the probable source of these depth errors is presented

ISSN:0143-1161    

DOI:10.1080/01431168508948428

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor