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represent the family units (in the case of single dwellings) upon which much 
forward planning is based. 
LANDSAT 
(Band 4- Band 5 ) 
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0 1°2 34° 5 8g 7 979 4 Ww 12-9 1 15 1% 
PARCEL SIZE  M2x100 
FIGURE 1: Residential parcel size (Sydney) versus difference in 
Landsat bands 4 and 5. 
FUTURE SATELLITES - RESOLUTION AND POTENTIAL 
During the 1980's a number of higher resolution satellite systems will be 
launched. Two of the most important (and nearest to launch) are the United 
States Landsat D TM (Thematic Mapper) and the French SPOT satellite. Landsat 
D TM will have seven spectral bands including a thermal infrared band, and a 
ground resolution of 30 metres in the visible and near infrared bands. SPOT 
will have four bands, two in the visible and one in the infrared, with a ground 
resolution of 20 metres, and a broad visible-infrared band with a ground 
resolution of 10 metres. This system will also have the potential for obtaining 
stereoscopic coverage. 
The pixel sizes of these two systems are compared with the typical dimensions 
of residential features on the urban periphery, in Figure 2. For Sydney, at 
least,this region will derive the greatest benefit from satellite monitoring. 
It can be seen that the proposed resolution elements will be more comparable 
with the size of features that require detection, and in addition intra-pixel 
mixing will be reduced as there will be fewer surface types within a pixel (in 
certain circumstances only one or two). Reduced mixing can have a number of 
advantages. 
(a) the reliability of prediction of surface percentages within pixels will be 
considerably improved because of the increased data redundancy, 
$93 
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