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Medium Spatial Resolution Applications Landsat and Systeme Pour l'Observation de la Terre (SPOT) systems are two of the most commonly used sources of medium spatial resolution data. Both systems are designed to obtain repetitive remote sensing data of the earth's surface and both have similar orbital characteristics. However, the means by which the systems acquire data is significantly different. The second generation Landsat satellites carry a MSS system as well as a Thematic Mapper (TM), a sophisticated data acquisition system, that obtains data in seven wavebands. Whereas the SPOT satellites obtain data through a pushbroom system. This data acquisition system gathers information in two modes, firstly in an MSS mode at a radiometric resolution. Secondly it obtains a panchromatic image, this is where the imaging is achieved in a single spectral band, within the visible range of the spectrum. SPOT systems also have different viewing capabilities to those of Landsat, as the SPOT sensors collect data from a 117 kilometre strip of area, compared to the 185 kilometre swath for Landsat. Additionally SPOT has the capability to obtain data from distances of 450 metres either side of the satellites ground track. This off-nadir viewing ability of SPOT, of which is not shared by Landsat, provides a number of advantages. As this flexible viewing means that this satellite is more likely to be utilized for the monitoring unpredictable events, such as monitoring pollution and volcanoes. High spatial resolution satellite applications Images acquired from high spatial resolution satellites have spatial
resolutions of 10 metres and will allow small individual targets to
be identified. Aerial photography tends to be the main type of image
utilised in situations where high-resolution data is required. As aerial
survey can be instigated rapidly, they are key processes of data collection
for rapid onset weather extremes, such as flooding. Additional planned
applications for high-resolution satellites included, city planning,
traffic
monitoring, property marketing and pollution monitoring.
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