||The need to effectively monitor our resources and measure
the impact of events on our environment is becoming increasingly important.
We now realise that some events that take place half a world away can
and do affect us and we appreciate that timely information has always
been a powerful and vital part of decision making. I put it to you that
in managing the precious resources of our world for future generations,
accurate information has never been more essential.
For some years now, the science (and sometimes art)
of remote sensing has been recognized as a valuable tool for monitoring
the Earth's natural resources. The definition of remote sensing has been
described as the means of sensing or measuring things (objects, areas
or phenomena) without coming into direct contact with the phenomenon.
An important question, therefore, is - what exactly is measured? - the
emitted, scattered and reflected electromagnetic
energy from the phenomena under investigation. From these measurements,
useful information is then extracted through visual or computer-assisted
interpretation. Satellite data, in particular, can provide relatively
inexpensive, repetitive datasets that can either augment or replace expensive
and often time consuming ground based monitoring programs. They provide
an instantaneous view of surface phenomena over large areas that are often
inaccessible to ground personnel due to physical or political reasons.