Remote Sensing
Today the team spent the day with Dr Paul Macey from Mapping
Geosciences (Western Cape) learning all about remote sensing techniques and how
these are used to do preliminary investigations of their mapping areas. Dr
Macey has substantial experience in geological mapping throughout Africa and
the applications and uses of advanced remote sensing techniques to aid in the
geological investigations.
Example of remote sensed ASTER imagery using various band ratio combinations to highlight possible variations in the geology. Typically different colours relate to different rock/soil chemistry
Remote Sensing stems from the manipulation of
band ratio combinations of aerial imagery to delineate various geological
units. The imagery is obtained from passive sources such as satellites or
airborne photographic sensors, or active sensors such as radar or lasers. The
material (e.g. rocks, soil, forestry, oceans) being captured by the sensors
will absorb certain amount of light and reflect according to several factors,
most notably, the chemistry of the material. Through the use of various band
ration combinations, rocks high in certain chemistries will reflect a specific
colour. Remote Sensing techniques can make estimations of what the chemistry of
these different colours are and further relate that to possibly geological
units. Through this mechanism, a preliminary geological polygon map can be
created and be cross checked while performing field work. This is particularly
useful once all different colour-coded polygon have been cross checked and can
aid in the production of an accurate geological map if 100 % field coverage is
not possible during the mapping.
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