|Remote sensing and geological mapping|
Hageman, B. (1990). Remote sensing and geological mapping, in: UniversiTECH 90: Remote sensing techniques and global change research. Seminar 30-31 March 1990. pp. 4
In: (1990). UniversiTECH 90: Remote sensing techniques and global change research. Seminar 30-31 March 1990. Vrije Universiteit Brussel: Brussel. 6 p. abstracts, 19 p. pp., more
Of course the human eye is a wonderfull instrument; however the demands thatadvanced science and techniques put on this precious gift of seeing is overasking our naturalcapabilities. For its original purpose our eye collects a total stew of a small part of theelectromagnetic spectrum which is translated "between our ears" into a colour picture. Thissystem is not able to collect waves outside this small part of the spectrum, cannot discriminateselectively between the different wave lengthes within this spectral section and is unable tomanipulate this information otherwise than in one type of colour composition. Although this isalready a miraculous achievement with respect to the possibilities of Remote Sensing it is notmuch more than a primitive steam engine compared to a last mark computer tuned machinery.On one hand however Remote Sensing uses rather simple techniques withrespect to data collection in particular. Just special films, sensitive for larger wave lengthesrunning into the "warm" infra red and the "radar" reach combined often with sets of filters todiscriminate special narrow bands out of this enlarged offer of wave lengthes.However the data originating from these relatively simple facilities are not onlypresented in an analogue form but also in a digitized version. This enables an almost endlessvariety of manipulations, not only by combining distinct vital wavelengthes in a proportionalway, but also by doing this in a non proportional manner or by using ratio's etc.. Moreoverthese sophisticated combinations can be translated from grey - tone imagines originating fromdigitized data, into all types of colour presentations even "stretching" the colours in vital andsensitive sectors of the initial grey - tones to accentuate contrasts. The result anyway, if wellmanipulated is a strongly accentuated visibility of certain phenomena.Features however that don't express themselves in specific electromagneticreflection or radiation are staying invisible "malgre tout".So what is the use of Remote Sensing for geological mapping?For some geological phenomena that have beside other properties, thepossibility to express themselves also by means of distinct electromagnetic reflection orradiation it mostly is relatively simple to be recognized.In other cases there sometimes are surprising side effects from geologicalfeatures that makes them recognizable on the images. Vegetation in this respect is traditionalbut many other features can be puzZled out by creative thinking. Also "pattern recognition"may play an important role in exploring the geological phenomena. Among all the otherconfusing liniations that are often predominantly present on the Remote Sensing imageries.