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3.2 Water<br />
Figure 4: Typical Water Area Image<br />
This section took a look at four water samples present in the sample image<br />
(comprising of three sections of lake, and one of river) to see if the spectral values<br />
could be used to control and calibrate image processing of land polygons. The<br />
results were good and indicated several unique properties for this cover that could<br />
be used to calibrate a key in relation to surfaces being studies. The percentage of<br />
the image covered by water was proportionally small but the lake section made up<br />
the biggest single polygon. Of the water, the majority of the polygons were for<br />
was drains, several streams (ranging from three to less than a meter in width<br />
stream), there was also a river and lake present. The streams and drains were<br />
eliminated from the study This was for two reasons; firstly they have very small<br />
width (less than a meter in some cases) and were often obscured by overhanging<br />
vegetation and secondly they are already captured and any spectral analysis would<br />
only be of use as comparative values to use against the rest of the image –which<br />
was not possible due to the vegetation.<br />
Variations between the samples were slight, suggesting that lower flown<br />
photography would be necessary to compile any useful information regarding<br />
sediment levels, but allowing good baseline figures to be derived from the values<br />
present. The pixel value was almost uniformly two thirds less than the image<br />
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