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3.9 Pasture<br />
Figure 15: Typical Pasture Area Image<br />
This part of the study looks at spectral values for areas of pasture within a section<br />
of aerial photography, corresponding to 3sqkm of semi rural county Galway. The<br />
aim is to establish baseline data for the relatively stable spectral values returned<br />
from this type of land cover. The polygons in question correspond to field areas<br />
bounded by walls or fences (and occasionally roads and water bodies). They can<br />
be described as stable in terms of their usage; they will almost always be turned<br />
over to one particular usage –in other words they will not contain large areas of<br />
separate land cover within them (other than islands of forestry or water, which is<br />
already captured and can be eliminated from the image processing). The study<br />
looked at nine separate areas, two of which were freshly cut. The values returned<br />
were uniform with the variation in the two freshly cut fields remaining consistent.<br />
Another feature which emerged was the low level of deviation for values in the<br />
red colour band, approximately one third of that returned from the image as a<br />
whole, across all the samples.<br />
Pasture Sample 1 Mean Pixel Value Standard Deviation<br />
Red 126.131 8.538<br />
Green 173.848 9.45<br />
Blue 109.745 12.646<br />
86
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