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4 Testing
This chapter describes a set of tests for known polygon types in the imagery being
used in the study. Four land use types were selected; pasture, rough pasture, marsh
and bog; and the polygons clipped from the raster imagery for spectral analysis.
The process followed the outline presented in Chapter 2, with the vector
coordinates being identified from the ordnance survey data. This set of
coordinates was then used to extract the corresponding section of image, which in
turn was analyzed for its spectral values. The overall results were good in terms of
there being unique proportional pixel count values present in the polygons
(selected from across the image with typical biasing factors such as shade present).
Of the four sample areas, bog and pasture had the least amount of standard
deviation –it was possible to automatically classify pasture even with a high
proportion of shade present in the image section. Marsh and rough pasture had
similar levels of standard deviation but can be distinguished by a dip in values
between the shade and vegetation range in rough pasture, which was not present in
the marsh polygons. This chapter is divided into four sections; as with the
previous chapter the results are grouped according to a particular area of interest,
starting with a look at the values from the known pasture polygons.
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