ISSN:0143-1161    

DOI:10.1080/01431168708954770

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431168708954771

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Remote sensing is a technique used in scientific and technological approaches to geographical research. In the scientific approaches (of which the empirical are the most popular) the motivation is curiosity, the goal is knowledge and the methodology is often induction to derive theory and then deduction to verify theory. In the technological approaches the motivation is human need, the goal is the application of knowledge and the methodology is design. This review discusses both approaches, concentrating on the problems of taking a scientific approach and the unwillingness of geographers to accept an often more suitable technological approach. It is argued throughout that both types of approach can be valid, both can be useful and both are suitable methodologies for remote sensing in geography.

ISSN:0143-1161    

DOI:10.1080/01431168708954772

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This study is concerned with a general model of satellite data interpretation. For this interpretation, the user has to abstract a particular dimension from the landscape considered as a system. The review of some applications in remote sensing has revealed that all the algorithms used in image processing for land surveys consist of operations on three kinds of information extracted from satellite data. In cartographic applications and in land use inventories, the emphasis is laid on the spectral information. When the aim of the study is to model the geographical properties of the landscape, the analysis of spectral information is combined with an analysis of the spatial information. Finally, when evolutionary studies are conducted, the temporal information is introduced.

ISSN:0143-1161    

DOI:10.1080/01431168708954773

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The use of field measures of slope angle, slope aspect, cover type, crown size and crown density is evaluated in appraising the variability of Landsat Multispectral Scanner (MSS) spectral responses for 182 sample sites within Crater Lake National Park, Oregon. Multiple linear regression models indicate that 73, 72, 71 and 57 percent of the variation in the mean response of MSS bands 4, 5, 6 and 7, respectively, was explained by the environmental variables entered into the models. In general, crown size and crown density are less important in altering spectral response than terrain orientation. This type of analysis is useful in guiding field work for remote sensing studies into areas that are environmentally diverse and which are, therefore, capable of significantly altering the spectral response of cover types.

ISSN:0143-1161    

DOI:10.1080/01431168708954774

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Landsat MSS data were used to simulate low resolution satellite data, such as NOAA AVHRR, to quantify the fractional vegetation cover within a pixel and relate the fractional cover to the normalized difference vegetation index (NDVI) and the simple ratio (SR). The MSS data were converted to radiances from which the NDVI and SR values for the simulated pixels were determined. Each simulated pixel was divided into clusters using an unsupervised classification programme. Spatial and spectral analysis provided a means of combining clusters representing similar surface characteristics into vegetated and non-vegetated areas. Analysis showed an average error of 12·7 per cent in determining these areas. NDVI values less than 0·3 represented fractional vegetated areas of 5 per cent or less, while a value of 0·7 or higher represented fractional vegetated areas greater than 80 per cent. Regression analysis showed a strong linear relation between fractional vegetation area and the NDVI and SR values; correlation values were 0·89 and 0·95 respectively. The range of NDVI values calculated from the MSS data agrees well with field studies.

ISSN:0143-1161    

DOI:10.1080/01431168708954775

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The spectral behaviour of an incomplete cotton canopy was analysed in relation to solar zenith angle and soil background variations. Soil and vegetation spectral contributions towards canopy response were separated using a first-order interactive model and consequently used to compare the relative sensitivity of canopy spectra to soil background and solar angle differences. Canopy reflectance behaviour with solar angle increased, decreased or remained invariant depending on the reflectance properties of the underlying soil. Sunlit and shaded soil contributions were found to alter vegetation index behaviour significantly over different Sun angles.

ISSN:0143-1161    

DOI:10.1080/01431168708954776

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The study is focused on the characterization of vegetation formations in a Mediterranean area (943 km2) located in southern Spain: herbaceous canopies (rangelands), shrubby vegetation (‘matorral’) and complex woody/herbaceous formations (‘dehesa’). Vegetation formations (physiognomical units) have been characterized by their spectral responses in the six reflective TM channels and by vegetation indices. From the ratio index TM4/TM3 there has been derived a map displaying seven classes (water, bare soil and five biomass levels reflecting the hierarchy of vegetation formations). Channels TM3, TM4 and TM5 have been considered for a supervised classification into nine land-cover categories (seven vegetation formations, bare soil and water). The proportion of correct classification of vegetation formations is about 78 per cent when considering test areas. Classification made from three principal components gives similar results.

ISSN:0143-1161    

DOI:10.1080/01431168708954777

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Monoscopic and stereoscopic interpretation of FGEOS (First Generation Earth Observation Satellites) images were applied comparatively in order to divide the region of Central Peloponnesos (Greece) into physiographic units for thematic mapping concerning geomorphology, soils and land use. A stereo pair of Landsat-1 black and white prints and a false-colour print at 1:250000 scale were used in order (1) to construct a reconnaissance physiographic map, (2) to construct a land use map and (3) to reconsider the monoscopic interpretation techniques, because of the newly-developed SPOT stereo capability and 10 × 10 m ground resolution. The known problems reported from the FGEOS 79 × 79 m resolution could reduce the effectiveness of any interpretation method. However the results show that the stereoscopic interpretation and physiographic analysis of satellite images improve the accuracy of boundaries and increase the number of mapping units, and consequently they are expected to minimize field work, laboratory analysis, field staff and the total cost of surveying.

ISSN:0143-1161    

DOI:10.1080/01431168708954778

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This article reviews experience in radiometric corrections of satellite and airborne remote sensing data at the Canada Centre for Remote Sensing (CCRS) during the period 1972 to 1986. It also describes current research areas and recommends areas of future research where high priority is important for global change monitoring and for the derivation of quantitative information from remotely-sensed data in the solar reflective spectral regions. Throughout its history, CCRS has directed its efforts towards meeting specific needs. For satellite data (Landsat MSS, Thematic Mapper, AVHRR, and now SPOT HRV), the progression has been from relative calibration of detector elements (destriping) to absolute radiometric calibration of digital data. The routine use of atmospheric corrections anda prioriknowledge of terrain reflectance properties have been introduced into the generation of specialized digital enhancements for photographic products. This has required the investigation of a wide range of radiometry-related problems and the embodiment of the results into production systems. As these results move from the research stage into operational use, other problems are becoming important, particularly view angle effects and radiometric effects induced by topography. A concurrent issue demanding attention is the need for more accurate radiometric calibration and intercalibration of sensors from a number of satellites including Landsats 1-5, SPOT and NOAA 6-10. Airborne sensors at CCRS have received similar attention. Again, the emphasis has been on routine application of accurate correction techniques in a production environment and the progression has been from relative calibration to absolute calibration to the current work towards routine atmospheric corrections. Particular characteristics of airborne sensors have often required innovative solutions, which are briefly described in the article, with references to more detailed descriptions.

ISSN:0143-1161    

DOI:10.1080/01431168708954779

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor