Data Sourcing
Commercial remote sensing satellites have been orbiting the earth since 1972. The first generation satellites (Landsat MSS, TM and Spot XS) were designed to cover large areas for land use, environmental and geological studies. The launch of IKONOS in 1999 and Quickbird in 2001 are leading the way of the new generation high spatial (ground) resolution satellites and many are planned to follow. The advantages of satellite imagery is it’s availability off-the-shelf and repeat coverage which allow changes to be detected over many years.

Radar instruments can operate during the day or night as they emit their own energy (active sensor) rather than receive reflected radiation (passive sensor). Radar will also penetrate through cloud which is particularly useful in equatorial regions where there is persistent cloud cover.

When deciding which satellite imagery is to be used, there is usually a compromise between spatial resolution and spectral resolution. Spatial resolution refers to the area on the ground represented by each pixel in the image. Spectral resolution refers to the number of bands, where each band represents a portion of the electromagnetic spectrum or specific wavelengths that the sensor can record.

As an independent applications provider, Geosense advises its clients on the best imagery data and technical solution for their project requirements. This involves finding data available in archives and if necessary, tasking satellites where data does not exist.

Top Left: Quickbird, Ikonos panchromatic, Ikonos multispectral, IRS, Landsat MSS, Landsat TM and Spot XS