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In 2002 S. Phinn, M. Stanford, P. Scarth, A. Murray and P. Shyy attempted to
apply a similar technique to that used by Megan Lewis in her 1998 study of
vegetation communities, only with reference to vegetation impervious hard
ground in urban areas. This study has similar goals to this thesis, but was
undertaken in an Australian urban context, and does not make use of existing
vector mapping and polygons. In the study by Phinn et al the authors conducted a
survey of the area surrounding the city of Brisbane, in an attempt to establish an
image processing method which would yield information about the urban
environment. In particular they focused on vegetation –impervious surface-soil, or
hard ground. They identified 60 spectral zones which they aggregated based on
their location, they were able to identify distinctive zones of hard ground based on
their per-pixel classification. The data used was from the Landsat5 Thematic
mapper and 1:5000 scale aerial photography. Their aims were to deliminate land
cover and use types, identify areas of impervious and pervious surfaces. One of
the most difficult aspects they encountered was classifying non-vegetation areas
into exposed soil and developed surfaces. They extracted the information along
transects radiating from Brisbane’s city centre. The study noted that water bodies
and vegetation were “separate in all spectral bands” (Phinn et al, 2002). The
maximum separation along the cleared hard ground was along bands 3, 4 and 7.
the authors concluded that the increased resolution enabled more detailed
assessment of the surface.
One recurring theme within these studies of spectral analysis of aerial
photography (and satellite imagery) was that the success of the study is dependant
on three main factors; the resolution of the photography, the correct segmentation
of the target areas and an accurate knowledge of the colour bands which apply to
the study. To a lesser extent it is also important to introduce methods to correct for
haze, cloud cover and shade. These last three considerations are not the focus of
this study; the fact that they warrant the complete focus of previously published
papers indicates that it would not be possible to completely eliminate their
presence. By applying some of the aspects of masking (Cordero-Sancho & Adler)
and adjusting for shade (Tuominen & Pekkarinen) it might be possible to reduce
the influence of these in the outcome to within an acceptable error margin for high
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