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Figure 6: Sample area as a mosaic of polygons<br />
The purpose of the study is to identify an automated software process to do this.<br />
The user would start with the requirement to identify the percentage of a certain<br />
property in the photography: throughout this thesis the example of impervious<br />
surface area is given but this could also be a fungal infection affecting crops, the<br />
spread of invasive plant species, the extent of flood damage etc. What the<br />
sampling of water polygons is doing is attempting to create a set of automated<br />
conditions which the software would initially retrieve to set a base for the<br />
algorithm. The user would then select an area from the vector data where the<br />
target values were present. This area would be in the format of a specially coded<br />
polygon composed of vector data; either using those in the ordnance survey data<br />
or appending lines to controlled data to fully enclose the target sample (and<br />
creating the necessary vector set). Once identified the target area could be<br />
calibrated against the value for water (among others) and areas not relevant<br />
eliminated.<br />
As every section of the image will be composed of an area polygon (taken from<br />
the vector data) which in general enclose relatively small areas it should be<br />
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