Monitoring the earth by remote sensing




In August 1996, in the sea off the west coast of Singapore, the captain of an oil tanker thought that he could not possibly be under observation. So he spilled a huge volume of the vessel's cargo, polluting the waters and wreaking havoc on the marine life in that area.

He later paid dearly for his negligence, He did not reckon with remote sensing technology through which his guilt was subsequently proven beyond doubt in a Singapore court. The incriminating image was provided by the Centre for Remote Imaging, Sensing and Processing (CRISP) in Singapore.

That was the first ever satellite remote sensing image accepted as an evidence in an ocean pollution case. CRISP has since been cooperating with the Maritime and Port Authority of Singapore in the regular monitoring of pollution in the neighbouring seas.

Technology has many uses

The technology of remote sensing, the use of recording devices at a considerable distance from the subject under study, has, of course, a good number of applications other than sleuthing against polluters. It is being used to keep track of forest fires that, because of the haze that they produce, are difficult to monitor from the air. It is also used for vegetation and land use studies, coastal and ocean studies and weather monitoring.

The recording devices in remote sensing, such as cameras, radar systems or radio frequency receivers, pick up reflected light or other forms of radiation from the subject.

In the ASEAN region, national agencies engaged in remote sensing are undertaking cooperative projects that promote the region's capability in this technology. This is being done through training and programmes that make use of information provided by satellite images and aerial photographs.

The key national agencies involved are: the National Coordination Agency for Surveys and Mapping (BAKUSORTANAL) and the Agency for the Assessment and Application of Technology (BPPT) of Indonesia; the Malaysian Centre for Remote Sensing (MACRES); the National Mapping and Resource Information Authority (NAMRIA) of the Philippines; the Centre for Remote Imaging, Sensing and Processing (CRISP) of Singapore; the Thailand Remote Sensing Centre; and the National Centre of Natural Sciences and Technology of Vietnam.

Satellite coverage

Indonesia, Thailand and Singapore operate ground stations that receive images from several satellites such as those of SPOT of France, ERS of the European Space Agency, and RADARSAT of Canada. The ground station of CRISP alone covers almost the entire ASEAN region.

Through the CRISP WebPages (http://www.crisp.nus.edu.sg), users can search the complete catalogue of CRISP's sizeable image archive. Location maps and quicklook images are available on-line to assist users select images for their applications.

In collaboration with the Ministry of the Environment and the Meteorological Service Singapore (MSS), CRISP has been monitoring land and forest fires in the ASEAN region on a daily basis. Using hot-spot data from MSS, CRISP zooms in on the fire areas with SPOT images.

In the 20-metre resolution SPOT images, the details of fire plumes could be seen and from these it could be determined whether the fires were due to natural causes or human activity. Such information could be helpful to authorities in fighting and controlling the fires.