Image Processing Reference
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Fig. 5.4 Examples of informal urban development with different sensors and spatial resolution
The ideal spatial resolution of an image for a given application will therefore be
several times smaller than the size of the smallest object that needs to be identified.
In this context, it is important to note that average
object sizes differ between regions. Welch ( 1982 ) sug-
gested that a spatial resolution of 5-10 m is required
for performing a reliable urban land use classification
in Asian cities, while a resolution of 30 m could be
sufficient in the USA. Many studies with medium-
resolution data (e.g., 30 m) can be found for cities in the
USA (e.g., Gluch 2002 ; Qiu et al. 2003 ).
Some authors suggest the use of geo-statistical techniques for selecting an
appropriate spatial resolution (Woodcock and Strahler 1987 ; Atkinson and Curran
1997 ). The main assumption underlying these techniques is that a scene consists of
discrete objects. Consequently, an image resolution that is larger than the object
desired accuracy is a
common criterion
for the selection of
sensor data needed
in a given urban
analysis application
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