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cycle being suggested here to present an early estimate of the type of surface<br />
coverage the image is composed of.<br />
One other factor that could be included in a search for rough pasture is the<br />
presence of symbols within polygons of this type in the vector mapping. Initial<br />
steps within the algorithm could extract all polygons and all indication symbols<br />
(the polylines surrounding known areas of rough pasture are not coded) and retain<br />
the set of polygons where they intersect. These could then be discounted from the<br />
automated image analysis.<br />
The second sample area was an area of water. This was taken form a lake present<br />
on the plan because, as was indicated earlier in the study, only water polygons<br />
above the level stream (wider than 3m) return a pixel sample useful for reference.<br />
The values obtained matched those identified in the water area sampling in this<br />
thesis and contrasted with values for rough pasture (less than 50% of the red and<br />
50% of the green colour band values of rough pasture). The level of standard<br />
deviation varied greatly also with values almost six times higher in rough pasture.<br />
This makes water a good benchmark to rate the probability of rough pasture<br />
against, using the percentage increase on the values for the red and green colour<br />
bands as a reference.<br />
The third value sampled was a section of road. This sample is unique to this part<br />
of the study, so as to avoid overlap with road samples taken elsewhere and ensure<br />
the values remain consistent for the feature type. Road was selected for sampling<br />
because, as with water, it contains relatively unique spectral properties with a low<br />
level of standard deviation. This allows it to be used as a stable contrast to the<br />
values found in rough pasture (which are similar to some types of forestry and<br />
contain a high level of standard deviation in all three colour bands).For the red<br />
colour band the road had an increased mean value of over 20% on those found in<br />
rough pasture, with a standard deviation of less than a third of the rough pasture<br />
value. The green colour band showed the highest difference returning a value of<br />
over twice that found in the rough pasture samples and, as with the red colour<br />
band, a level of standard deviation less than a third of rough pasture. The blue<br />
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