ISSN:0143-1161    

DOI:10.1080/01431169108955249

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431169108955250

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The classification of land cover on remotely sensed imagery is usually undertaken in a per-pixel format within an image file or in a per-field format within a non-image file. The latter is more accurate but does not produce an image output and is not readily input to a vector-based geographical information system. We propose setting the pixels in each field to a representative statistic for that field and then using a per-pixel classifier to perform a per-field classification in an image file. This procedure was evaluated using SPOT high resolution visible (HRV) imagery. The highest classification accuracy of 62.1 per cent (12 class) was achieved using measures of prior probabilities and image texture within the proposed per-field format.

ISSN:0143-1161    

DOI:10.1080/01431169108955251

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Cut-over area and boundary placement accuracies from analogue SPOT Panchromatic (PLA) and Multispectral (MLA) Linear Array images were determined for forest cut-overs typical of the Canadian Prairies. Cut-overs were mapped using a Procom-2 to optically project images on to a photogrammetrically-produced planimetric base map. Overall area accuracies for the SPOT PLA and MLA images were 90-7 per cent, and 89-6 per cent, respectively. The influence of increasing accuracy with increasing cut-over size must be considered, however, when interpreting these figures. Proportional regression models were fit to improve the estimates of cut-over areas. On average, boundary placement errors were 24 m for the SPOT PLA, and 26 m for the SPOT MLA. These errors were influenced by the 25 times enlargement factor encountered in the optical projection, and the scale of the base map itself. The base map scale of 1:20 000 was a limiting factor in this study as both plotting errors and pen line widths contributed to existing map errors. Under the forest conditions evaluated, SPOT images offered an approximate five to one cost savings in data acquisition, and are more efficient to interpret and map in comparison to conventional air photos.

ISSN:0143-1161    

DOI:10.1080/01431169108955252

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The Andaman Nicobar group of islands in the Andaman Sea are blessed with luxuriant tropical vegetation. During recent years, vegetation in these islands has been under tremendous pressure due to increased settlement and commercial extraction, Landsat TM data of the Baratang forest division of the Andaman group of islands has been used to prepare forest type maps using visual and digital methods. Digital enhancement techniques have been evaluated to discriminate forest types in a typical environmental set-up. The mapping techniques have been compared with respect to classification and accuracy levels. Finally, the land transformation in the forest division has been studied using past aerial photographs. The study highlights the appropriate methodology required to map forest types.

ISSN:0143-1161    

DOI:10.1080/01431169108955253

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The classification accuracy obtained from the classification of satellite images using pixel-by-pixel conventional methods can be improved if the contextual information is considered jointly with the spectral information in the same strategy of classification. A computer program has been developed to implement a contextual classifier algorithm. The accuracy improvement was evaluated and tested in two pilot zones of central Spain. Two indices were defined in order to analyse the homogeneity effect produced by the contextual classifier.

ISSN:0143-1161    

DOI:10.1080/01431169108955254

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Existing land use and cover maps and the aerial photographs they were derived from were studied for a number of different landscape settings using spatial analysis techniques. The purpose of this study was to (1) determine if spatial variations in land use and cover could be quantified and characterized, (2) investigate the spatial scale relationships between land use and cover parcels and their image brightness composition on remotely-sensed images and (3) assess the relevance of these findings to the selection of appropriate remote sensor spatial resolution for image classification of land use and cover types.

ISSN:0143-1161    

DOI:10.1080/01431169108955255

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

An attempt to derive a relation between spectral data of rice canopies and their grain yield has been made in the Cuttack and Puri districts of Orissa for Kharif rice using Landsat MSS digital data of three years (1984-1986). Necessary sensor-to-sensor transformations of Landsat MSS to IRS LISS-I and acquisition date normalization with respect to a typical rice growth profile were also carried out, Using such an empirical relation, rice yield was estimated for Kharif in 1988 using IRS-IA LISS-I data at district level. Deviation of the estimated yields from the reported figures varied from 2 per cent to 14 per cent at the district-aggregated level.

ISSN:0143-1161    

DOI:10.1080/01431169108955256

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The question whether the Bidirectional Reflectance Distribution Function (BRDF) has a one-to-one correspondence with the surface microstructure is addressed. A technique is developed to simulate a wide range of microelements and their BRDF. Results from the simulation show a significant number of cases of equifinality in which a variety of microstructures exhibit the same BRDF. Analysis of these cases suggests that there are many distinctively different combinations of structural properties which can balance the effect of structure on the reflected radiance field. A comparison of field measurements with the simulated cases confirms that BRDF equifinality must be considered in remote sensing applications where there is a need to derive surface properties like roughness, microstructure and texture from satellite data.

ISSN:0143-1161    

DOI:10.1080/01431169108955257

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The effect of different tillage on the microwave backscatter from grain stubble plots was investigated as a function of frequency, polarization, row direction and type of tillage implement. The Canada Centre for Remote Sensing (CCRS) truck-mounted FM-CW scatterometer was used to make the radar backscattering coefficient (σ°) measurements. Factorial analysis found the effects of row direction to be as significant as the differences between tillage implements on σ°of like polarized data. The cross-polarized data were less sensitive to row direction effects. There were no significant differences betwen the HH and VV polarizations at any frequency investigated. An airborne SAR image of an area close to the experiment site was qualitatively used to demonstrate the effects of tillage and row direction. The scatterometer results and airborne SAR interpretations indicate the necessity of accounting for row direction, as well as surface roughness, when using SAR data for soil mapping applications. Techniques are identified which may allow estimation of these roughness effects. Radarsat, and other Earth observation satellites will view agricultural fields with many row aspects and thus research needs to be conducted to determine the effects of row direction on σ°at the anticipated azimuth view angles.

ISSN:0143-1161    

DOI:10.1080/01431169108955258

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor