3-5 Remote Sensing with Satellite Imagery

Satellite remote sensing is a modern technology to obtain digital image data of the terrain surface in the eletro-magnetic region of visible, infrared and microwave.

Multi-spectral bands including visible, near-infrared and/or thermal infrared are most commonly used for production of land use map, soil map, geological map, agricultureal map, forest map etc. at the scale of 1:50,000 ~ 250,000. A lot of earth observation satellites for example landsat, SPOT, ERS-1, JERS-1, IRS, Radarsat etc. are available.

Synthetic aperture radar (SAR) is now becoming a new technology in remote sensing because SAR can penetrate through clouds, which enables cloud free imagery in all weather conditions.

Satellite images have different ground resolutions depending on the sensors used as listed in Table 3.3.

Since the cold war was over in 1990's, very high resolution satellite imagery with ground resolution of 1 to 3 meters will become available from 1998. Such high resolution satellite images are expected to identify individual houses in urban area. Table 3.4 shows high resolution satellites proposed to be launched by three US commercial companies.

The high resolution satellite images are highly expected to apply to urban GIS.