Contrast enhancement, one of the image processing techiques, is developed on the Multispectral Data Analysis System (MDAS) for enhancing the LANDSAT data. The purpose of image processing for enhancement is to improve the obscure objects data in the image to stand out more readily for good sensing to the human eye. It is observed on MDAS that some of the LANDSAT scenes when examined on the color display, give inadequate information for the required objective of interpretation. This is due to poor tonal contrast in the scene because of prevailing climatological conditions at the time of satellite pass over that area. Also, the LANDSAT data usually occupy a small subset of the total brightness range 0–127. To provide optimal contrast and variation for color compositing, contrast enhancement may by performed on the data before going to trie information processing (categolization) on the landsat scene. This paper describes the algorithms of parametric linear and non linear contrast enhancement techniques. A typical example to differentiate the degree of salinity in the soils was tested with the suggested algorithms and the results are tabulated in the form of photographs. The test area is selected from Haryana (frame no. 158-040 dated 2nd May, 1977) for testing the algorithms. The enhancement software developed on the MDAS stretches all the four Landsat bands and generates an output tape with the format similar to LANDSAT computer compatible tape (CCT). The stretched results of 5 and 7 bands are displayed in this paper. A false color composite which appears as on the color displya could also be generated from 4, 5 and 7 bands. The enhanced output was found to be useful for easily categorizing the data into various categories on MDAS. 相似文献
A “hot blob”, distinct hot region, is identified over Vidarbha in the south-central parts of the Indian subcontinent during the pre-monsoon season from the analysis of gridded surface air maximum temperature data from India Meteorological Department for the period 1951–2019. Spatial distribution and frequencies of temperatures?>?40 °C and?>?42 °C establish the hot blob over Vidarbha region. A similar analysis of simulated maximum temperatures from the NEX-GDDP substantiates the revelation of the “hot blob” over Vidarbha. Further, analysis of the wind circulation at 850 hPa over South Asia region indicates that the “COL” region between the two seasonal high-pressure systems over the Indian Ocean seas, Bay of Bengal and Arabian Sea promotes accumulation of heat over Vidarbha. Further, horizontal temperature convergence complimented by strong local heating of the black soil aids and abets the sustenance of the “hot blob”. This “hot blob” region is observed to be hotter as well as having higher frequencies of hot days than the north-west desert Rajasthan region and assumes importance as its modulation causes heatwaves over the south-east coastal regions. This study establishes the presence of the hottest region over Vidarbha in south-central parts, paradoxically hotter than the desert north-west region of India.
Chemometric methods are powerful in finding hidden structures and latent information in environmental and other analytical datasets. This work shows the application of cluster analysis, discriminant analysis, and support vector machines for the evaluation of waterbodies in the Polish Tatra Mountains. After the analysis of in situ parameters and the determination of concentrations of cations and anions, cluster analysis shows that the previous separation into Western Tatras and High Tatras should be reconsidered, as the Bystra stream in the border region might have been incorrectly assigned to the Western Tatras up to now. Discriminant analysis not only confirms the geographical separation of waterbodies, but also the fact that the sampling time is a crucial factor in environmental analysis. Samples taken in different months do not result in a homogenous object of investigation. A uniform date should therefore be chosen so that the results will be comparable. The influence of the sampling month on the classification of samples is also approved by support vector machines. 相似文献
Abstract Long‐term observations of the water balance elements were carried out in the Izhora plateau located in northwest Russia. As a result of these investigations, the average recharge of the Leningrad artesian basin located south of the plateau was calculated. The infiltration to the karstic groundwater table was determined on the basis of groundwater fluctuations in the observations wells. 相似文献
As global warming continues in the 21st century, one can expect a significant increase in the duration of the navigation period along the Northern Sea Route. In this study we found that, according to the representative concentration pathways 4.5 and 8.5 scenarios of the anthropogenic impact, the expected duration of the navigation period along the Northern Sea Route in the middle of the 21st century would be two to three months and three to six months by the end of the century. 相似文献
Summary In this Technical Note a parametric study, based on Dimaggio's (1978) approach, of the reinforcing effect of stone columns on the stability of road embankments is examined. For a certain embankment geometry, stability analyses of discrete soil and stone column elements were also carried out. The results of the above analyses are compared to the results of the analyses based on Dimaggio's approach. 相似文献
In several fields of Geophysics, such as Hydrology, Meteorology or Oceanography, it is often useful to generate random fields, displaying the same variabilitity as the observed variables. Usually, these synthetic data are used as forcing fields into numerical models, to test the sensitivity of their outputs to the variability of the inputs. Examples can be found in subsurface or surface Hydrology and in Meteorology with General Circulation Models (GCM). Different techniques have already been proposed, often based on the spectral representation of the random process, with, usually, assumptions of stationarity. This paper suggests that Empirical Orthogonal Function (EOF) analysis, which leads to the decomposition of the covariance kernel on the set of its eigen-functions, is a possible answer to this problem. The convergence and accuracy of the method are shown to depend mainly on the number of EOFs retained in the expansion of the covariance kemel. This result is confirmed by a comparison with the turning band method and a matrix technique. Furthermore, a synthetic example of non-homogencous fields shows the interest of EOF analysis in the direct simulation of such fields. 相似文献