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Digital Image Processing
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The use of image processing systems for the analysis of digitised Aerial Photography
Introduction to the study areas
- Flinders Ranges:
The Flinders ranges study area is situated in Southern Australia 75km NNE of port Augusta. The region is highly prospective for mineral deposits which include gold, copper, and industrial minerals.
Accurate lithological mapping is paramount to successful ore deposit delineation in this region (Rollings,1985). Existing 1:250,000 geological maps of the area contain insufficient detail with respect to the smaller outcrops which can be important for exploration activities.
Very subtle spectral differences exist between many of the rock units (Rollings,1988) Only by using sophisticated image analysis techniques can these subtle differences be exploited for the purpose of lithological mapping .
Remotely sensed data derived from satellite sensors lacks the required spatial resolution necessary for structural mapping at a scale appropriate for detecting the ore deposits of the region. Digitised aerial photography algorithms designed to extract line and edge features can be used to enhance small geological structures.
For this study area colour aerial photography acquired on the 20/6/84at 1:40,000 was used.
Figure 1: Location map of study areas.
- Warrenbayne:
The Warrenbayne study area near the town of Benalla, in Southern Australia, is predominantly grazing land affected by dryland salinity. Groundwater recharge and discharge areas therefore need to be mapped before treatment is undertaken (Fraser et al , 1989)
In the past the geographic data of the area has been in analogue form. As a result, detailed interpretation of the data has been limited. Once in digital format the data can undergo more extensive analysis.
The aim of digitising the aerial photography was to provide an objective image of the farm areas at high resoultion. This image then be used as a base to display other data, such as thematic classification and annotation (Ellis & Fraser, 1990).
The aerial photography for the Warrenbayne area is monochrome, at a scale of 1:25,000 , taken on the 14/12/87.
- Philip Island :
Cowes, the major town on Phillip Island, 120 km SE of Melbourne is a small coastal community relying on fishing and tourism for is economic survival.
The Township itself was chosen as a study area for a number of resons:
- the area itself has a diversity of land use, both urban and rural , with large areas of parkland and nature reserve.
- the area has been covered by color aerial photography at a scale of 1:10,000.
- large scale maps are available.
The aerial photography for Phillip Island was taken as part of the colour. 1:10,000 coastal mapping series on the 22/10/83.
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