ver 
face 
sat 
It 
have 
ive 
rban 
put 
(in 
en- 
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E uen M LEONE es me ER Bi ms eA SE 
  
  
  
Variance 
sut 
0 Housing 
Density 
  
FIGURE 3: Schematic relationship between response variance over a 
3x3 pixel neighbourhood and increasing housing density. 
(b) Band TM 7 (2.08-2.25 um) should have particular advantages in roof 
material discrimination. This band is particularly sensitive to hydroxyl 
ions in rocks due to clay minerals which are essentially hydrous aluminium 
silicates. These clays (particularly potter's clay and Kaolin) form the 
major component of terra cotta roof tiles, which at present is the major 
residential roofing material used in the Sydney region. 
(c) Other roofing material, such as concrete tiles, is impregnated with iron 
oxide, which has particular sensitivity in the 0.45-0.52 range (TM 1). 
Many of the newer residential areas on the edge of Sydney are now being 
roofed with cheaper concrete tiles (in contrast to older areas which are 
predominantly clay tiles) and so this band may contain additional urban 
information. 
(d) The thermal infrared band TM 6 (10.4-12.5) will have a spatial resolution 
of 120 metres which is generally too coarse for urban studies, however 
broader scale differentiation of natural and man-made features will be 
possible as man-made surfaces (particularly roads) are efficient absorbers 
and therefore emitters in this spectral range. 
COMMENTS AND CONCLUSIONS 
The new generation of satellite systems wili be of considerable advantage to 
urban studies primarily because of their increased spatial resolution which will 
result in an improved detection ot urban elements, a reduction in the number of 
surfaces per pixel and an increased potential for the use of textural data. 
The spectral bands of Landsat D TM, because of their placement and number, 
should allow greater discrimination of most urban surfaces. 
Of the two systems considered, SPOT wili have the higher spatial resolution and 
it would seem reasonable to suggest that ideally Landsat D TM data should be 
used primarily to discriminate surface types while the SPOT panchromatic data 
(at 10 metre resolution) be used to provide higher resolution cartographic and 
contextual information.  Individually, Landsat D TM and SPOT will have their own 
advantages, one having better spectral characteristics, the other better spatial 
characteristics. 
At the research level remotely sensed data is increasingly being analysed with 
existing auxiliary data, (such as topographic, socio-economic and tenure 
boundaries), and incorporated into spatial information systems. The increased 
spatial resolution of satellite remotely sensed data will aid this research and 
should lead to operational systems having benefit in a number of areas of urban 
study, for example; 
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