Evalution of digital processing techniques as applied to a landsat image of southwest Jordan
|Category||GIS & Remote sensing|
|Location||International Geological Congress,oslo 2008|
|Holding Date||07 October 2008|
A Landsat MSS image covering an area lying between the Aqabah Gulf and the southern margin of the Dead Sea was analyzed by digital image processing techniques to delineate various geological and structural features of southwest Jordan.This area was selected for investigation because of its tectonic significance as it bounded on the west by the Dead Sea Shear,an active plate boundary that has existed since the Miocene and seperates the Arabian plate from Sinai microplate.Three major digital image processing techniques were employed.
These are preprocessing,enhancement and classification.Types of lithology,Lineaments and topographic contrasts of southwest Jordan were used as criteria.Rocks underlying the studied area comprise a Precambrian crystalline basement complex and a Phanerozoic cover.They are composed mainly of Paleozoic sandstone,Cretaceous limestone,marl,and chert and Tertiary and Quaternary sedimentary and volcanic rocks in the northeast of the study area.Structurally,the area is intensively deformed by faulting of various ages,which control the local geomorphology and patterns of rock distributions.Linear discontinuities caused by faults and fractures from lineaments that are easily seen in Landsat image.Various enhancement techniques have been applied to the image.They include contrast streching,ratioing,filtering,principal components and color coordinates system.
Through these techniques the quality of lineament appearance was improved noticeably for purposes of geological and structural interpretation.A comparison has been made between various enhanced products utilized in this study in order to determine their potential in delineating different geological features such as lithologies,lineaments and topographic features.Results of comparison indicate that the combination of images processed by the first principal component,the second principal component and filtered first principal component,as assigned to the HIS system coordinates,provided better results than products of of other digital techniques.
This accomlished by a strong accentuation of contrast between different geologic features,which is needed for visual inspection of lineaments,structural features and mapping of lithological contacts,as well as assessment of topographic variations.Other enhanced image products generated by the techniques employing contrast streching,ratioing and filtering are generally less useful for purposes of the present study.On the other hand,results derived from the classification technique indicate that they are less capable of providing information about linear features that the enhanced technique.