摘要:

A model that simulates the volume reflectance of water is tested in laboratory conditions with three different sediments of known grain size distribution and spectral reflectance. The model uses, as its main input variables, the grain size distribution of the suspended sediment, the density of the grains and the spectral reflectance of the wet sediment from which the suspension comes. The spectral bands of the model are completely programmable and they have been adapted to correspond to green, red and near-infrared, as in Landsat MSS bands 4, 5 and 6. The grain size distribution, the reflectance in the three spectral bands and the density of the three sediment types had been measured and these measurements were used as input variables for the model to simulate the volume reflectance of the water, in the same spectral bands, for different suspended sediment concentrations. Each sediment type was used to produce several concentration levels in a specially prepared 1101 tank and the volume reflectance of the water was measured. The measurements were compared with the simulated results of the model. Then the model was modified to simulate the volume reflectance of a stratified environment, where the concentration changes with depth, and used to explain some discrepancies in the chromaticity transformation.

ISSN:0143-1161    

DOI:10.1080/01431169008955112

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Landsat-3 RBV, Landsat-5 TM imageries and SPOT PA stereopair diapositives were visually interpreted for the purpose of finding the accuracy of certain morphometric variables of three drainage basin sample areas in Central Macedonia, North Greece, drawn separately from each of the above three types of satellite imageries and comparisons were made between the efficiency of drainage systems drawn from each of the above imageries and the drainage systems extracted from the available topographic maps of 1:50000 scale.

ISSN:0143-1161    

DOI:10.1080/01431169008955113

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Raw weather radar reflectivities are processed and registered to the ground before radar rainfall measurements are used conjunctively with rain-gauge data to produce areal surface rainfall estimates. However, there are several factors causing errors in the returned power of weather radar signals, as well as other sources of error affecting the accuracy of radar rainfall measurements. In this study, several deterministic corrective techniques are applied to the digital processing stage of raw radar data to consider a number of sources of error, namely non-rainfall echoes, signal attenuation and wind effect. The results indicate that the deterministic techniques are still a necessary step for the ultimate improvement of surface rainfall estimates by the use of weather radar.

ISSN:0143-1161    

DOI:10.1080/01431169008955114

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The main objective of this paper is to determine the extent to which forest structural variables can be estimated from SPOT-1 panchromatic and multispectral radiance. The test site is the state-owned Pynven forest, featuring a large amount of evenly-aged pine stands from which those with Corsican pine (Pinus nigraAm.var. CalabricaLoud.) are selected. Investigated image parameters include waveband, first-order statistics estimators and sample window size. The forest stand parameters are stand density, stand age, average tree diameter, stand basal area, average canopy height and stand volume. Empirical linear models are constructed based on Bartlett's three-group method, followed by inversion and validation using an independent test data set. The green and red SPOT-1 waveband are useless for forest stand parameter estimation, and the arithmetic mean of sample window radiance is the only usable estimator from the set of tested statistical measures. Stand density and average canopy height can satisfactorily be estimated from the SPOT-1 data, with the panchromatic band yielding consistently better results than the infrared waveband. Radiance sampling in larger windows is usually more likely to capture structural variation of the forest on stand basis and results in more accurate estimation of the ground data.

ISSN:0143-1161    

DOI:10.1080/01431169008955115

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Landsat Thematic Mapper data, collected over central Michigan in the U.S.A., in October 1982, were digitally analysed to determine qualitatively and quantitatively their utility and potential to classify nine natural resources categories (e.g. red pine, jack pine, scotch pine, low conifers, hardwoods, grassland, water, wetland and other). Supervised classification with a maximum likelihood decision rule was employed to 22 especially selected single-, two-, three-, four- and six-band combinations (thermal band was excluded).

ISSN:0143-1161    

DOI:10.1080/01431169008955116

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The objective of the study is to obtain figures assessing the possibility of acquiring cloud-free images (Landsat TM and SPOT) throughout the countries of the European Community in the next campaign during a certain period of the year. Entry data transformation led to a very compact data set with an appropriate spatial and temporal resolution. Through a programme, estimations of the availability of good images can be easily obtained. It is shown that in areas of higher latitudes the disadvantage of bad weather can sometimes be compensated for by acquiring twice as many images, because of the bigger sidelap (over 50 per cent) of adjacent frames.

ISSN:0143-1161    

DOI:10.1080/01431169008955117

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In the framework of a pilot project of the Commission of the European Community concerning the application of remote sensing techniques for agricultural statistics, a specific study of an area in Northern Greece is being carried out at the Joint Research Centre, Ispra. This study involves the use of multi-temporal TM and SPOT data, in order to combine the spatial resolution of SPOT with the spectral resolution of TM and to gain in flexibility for the choice of dates. This approach is expected to overcome ambiguities in the spectral definition of crops, but significant problems are introduced, due mainly to the different atmospheric conditions present at the various dates. A study of the effect of the various factors on the spectral response of the crops will help to define a classification criterion based on their phenological variation.

ISSN:0143-1161    

DOI:10.1080/01431169008955118

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The aim of this study is to show the rapid growth of some agglomerations, in a country such as Greece. For that purpose, we use satellite images. The chosen method needs two spectral variables: the brilliance index and the vegetation index. The calculation of each of the two variables occurs at two different times, from two Landsat pictures covering the agglomeration of Athens and a part of the plain of the Mésogée. These two indices constitute the two components of a vector which discribes the direction and the amplitude of the change between the two times. The results are visualized with different colours which characterize the type of change. This method is conclusive: it enables one to show very precisely changes in the surfaces. Nevertheless, its weak point is the difficulty in defining the threshold between the places which have changed and the ones which have stayed stable.

ISSN:0143-1161    

DOI:10.1080/01431169008955119

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The paper comments on the usefulness of remotely-sensed data (Land-sat MSS images in both digital and photographic format—aeromagnetic data) in the tectonic analysis of areas of Greece. The island of Crete was the main case study area, while a general analysis was also carried out in the South Eastern Peloponessus.

ISSN:0143-1161    

DOI:10.1080/01431169008955120

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The purpose of this study was to apply thematic mapping using satellite imagery in assessing land-use patterns in W. Messinia, Greece. Various land-use classes of Messinia were mapped by using visual interpretation of false-colour composites based on Landsat Thematic Mapper (TM) and SPOT data. An identification, classification and mapping methodology was needed for the land-use forms that could be found in Greek territories with ecological and geological characteristics similar to those of Messinia.

ISSN:0143-1161    

DOI:10.1080/01431169008955121

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor