Geography Reference
In-Depth Information
(Roitman, 2005) and analysing street patterns within them (Grant and Mittelsteadt, 2004).
Aerial photographs have been used to identify gated beach resorts in Lebanon and to chart
their establishment (Glasze and Meyer, 2000). In Durbin, South Africa, Durlington (2006)
has used aerial photography to map changes in the landscape of gated communities from the
1970s onwards. He has shown that, although these communities are advertising themselves
as eco-friendly, they essentially wreak havoc on the environment during their construction.
7.2.2 Computer-assisted mass appraisal
Computer-assisted mass appraisal (CAMA) is a world-recognized approach to mass valu-
ation of property for tax purposes. CAMA is an umbrella term for computer software and
methodologies that are used to estimate the values of thousands of properties within a par-
ticular area that are stored within a database. The mass valuations are based upon the values
of a sub-sample of properties that have been inspected by a professional valuer. A statistical
model (usually based upon multiple regression) which specifies the value of a property as
a function of its attributes (such as dwelling type, floor area, lot size etc.) is estimated for
this sub-sample. This model is then used to estimate the value of all the remaining proper-
ties in the database, based upon their attributes. This method allows government agencies,
planners, real estate agents, property developers and other property experts to gain a clear
understanding of how the housing stock is valued across a particular area and, if kept up-to-
date, how the dynamics of the housing market are varying through time. It is used in many
countries as a method of maintaining and up-dating local taxation records.
Ensuring that there is 100 per cent coverage requires both a comprehensive map and
database of tax-payers and their properties. Owing to the lack of accurate cadastral maps
in many countries (Bird and Slack, 2004), aerial photographs in conjunction with GIS are
often used to provide digital base maps and, as discussed above, the property attributes. For
example, in Northern Ireland, a new local taxation based upon property values is set to be
introduced in April 2007. This is the called the council tax, which has been in operation
in the rest of the UK since the early 1990s. Over 700 000 homes across Northern Ireland
were valued using CAMA, the first time this method has been used in the UK. Data came
from several sources, including photogrammetric measurements from aerial photographs
which were also used to update domestic property attribute data at the same time. The
photogrammetric measurements were particularly useful in cases where other sources of
attribute information were missing. It also allowed attribute data from other data sources
to be checked and verified. The British government is currently investigating if the council
tax in England could be re-valued using similar methods (VOA, 2002b).
7.2.3 Visualizing, measuring and re-developing residential densities
High-resolution aerial photography is a good tool to visualize urban sprawl and also to
investigate and examine issues relating to housing densities (e.g. Burchfield
et al.
, 2006). In
particular it can be an effective tool for allaying public fears of increasing residential densities,
an issue of increasing importance in Western countries such as the United States and the UK,
where planners and designers are promoting 'smart growth' and are advocating a return to
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