摘要:

The FAO satellite remote sensing system ARTEMIS has recently been installed. It will support agricultural production and desert locust monitoring in Africa. In relation to these tasks, this study discusses and compares a rainfall and an evapotranspiration mapping technique for the Sahel region. Evapotranspiration maps reveal detailed soil moisture related patterns, resulting from rainfall. The mapping results indicate a potential of this technique for locust habitat monitoring and crop early warning.

ISSN:0143-1161    

DOI:10.1080/01431169008955176

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The introduction of mathematical modelling concepts to assess sensor performance is a necessary part of the graduate curriculum in remote sensing science. In this way, the concepts of sensor design and performance assessment under various imaging conditions can be best understood. In this paper, a graduate class project is described in which a static performance model was used to predict the minimum detectable temperature performance, the minimum resolvable temperature performance and the recognition performance of scanning and staring focal plane array (FPA) infrared imaging sensors with three different detector materials. Different seasonal, atmospheric, cold shield angle, target-to-background temperature contrast, bandpass and noise parameters were considered. Such studies are highly labour-intensive and (as in this case) may involve several hundred modelling runs. However, such projects provide a ‘real world’ experience for those who will design, use and analyse the data from imaging sensors. We present this paper as an approach to providing an in-depth understanding of sensor design concepts and limitations.

ISSN:0143-1161    

DOI:10.1080/01431169008955177

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An investigation of 20 marine macroalgae suggests that fluorescence emission could be used to distinguish macroalgal classes. Narrow waveband light was used to excite groups of accessory pigments in brown, red and green macroalgae and fluorescence emission measured at 685 nm, the wavelength at which chlorophyll a has its maximum fluorescence emission. Fluorescence induced by 540 and 465 nm wavelengths gave 540:465 fluorescence excitation ratios of 0·59±0·07 for seven brown algae, 3·67±0·56 for seven red algae and 0·28±0·07 for six green algae. These results suggest that fluorescence excitation signatures are relatively uniform within phylogenetic classes but differ substantially between classes. WhenEctocarpus siliculosus(Dillw) Lyng (Phaeophyceae) was cultured over a large range of light and nitrate regimes, the 540:465 fluorescence excitation ratio showed little variation. Somewhat higher fluorescence excitation ratios were correlated with tissue C:N ratios of 6·1–1·5. The ability to distinguish macroalgal divisions on the basis of fluorescence emission may allow the type and abundance of subtidal macroalgae to be characterized by existing laser-induced fluorescence methodology from low-flying aircraft.

ISSN:0143-1161    

DOI:10.1080/01431169008955178

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Synthetic Aperture Radar (SAR) images are used increasingly in applications of remotely-sensed data for land-use investigation and in the recognition of geological features. This is because SAR images are rich in textural information and textural characteristics of an image are found to be useful in identification of lithological units. For this reason, the automatic processing and interpretation of SAR images are often focused on texture analysis, including the extraction of textural information, textural filtering (enhancement of textural perception and texture classification. This Letter evaluates a set of new texture features which are extracted from thetexture spectrum. Some of the traditional texture features, extracted from the co-occurrence matrix, have been used for comparison with the new measures in the discrimination of different lithological units of an airborne SAR image. The results show the promising discriminating performance of the proposed features.

ISSN:0143-1161    

DOI:10.1080/01431169008955179

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor