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Abstract<br />
This study sets out an algorithm for the automatic analysis of controlled (flattened)<br />
aerial photography using ordnance survey vector data. It uses the vector to clip the<br />
aerial image into a set of small area polygons which are then analyzed for the<br />
spectral properties and classified according to the result. The study tests sections<br />
of aerial photography from a sample area in County Galway for specific spectral<br />
properties. This was to identify the type of ground cover and was achieved using<br />
an image key of spectral properties which was developed during the study. This is<br />
called training the image key. A testing section shows that it is possible to derive<br />
information about the land use type from these areas based on the range of values<br />
returned from a pixel count of spectral properties within a small area polygon.<br />
The study uses several open source software frameworks to complete the<br />
experiment, most notably the MATLAB based Mirone application, but can be<br />
extended to any software capable of handling irregular polygons in a projection<br />
system. The body of the study is set out in three chapters, the first detailing the<br />
process, the second detailing the sampling for unique values and the third details<br />
the testing which took place. Chapters 3 and 4 are sub divided into sections<br />
describing the research on specific land use types and their spectral signatures.<br />
Chopping an aerial image into a mosaic of (relatively) homogenous values, e.g.<br />
pasture, forestry, marsh etc., increases the accuracy of automated analysis. This is<br />
the first time that a spectral analysis has been attempted using ordnance survey<br />
Ireland small area polygons to clip the image. It is of interest to researchers,<br />
planners, developers etc., looking to simplify and automate this type of search<br />
over a large region.<br />
Note: Contact brian.sexton@osi.ie for a set of sample files for training the image<br />
key.<br />
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