The thermal infra-red linescanning technique which is dependent on the radiant temperature and emissivity of rocks and soil has been used increasingly over the past two years for engineering geological purposes. A description is given of the fundamentals of the technique and the equipment used in South Africa as well as the approximate cost. The main engineering geological application has been the mapping of proposed tailings dam sites on dolomites and gabbros in the Western Transvaal. Other applications of the technique are also discussed.
In the case histories considered, interpretation of the thermal infra-red linescanning imagery, as well as air photo interpretation, was also carried out and it is felt that both techniques should be used together for the best results.
The merits and limitations of thermal infra-red linescanning as applied to engineering geological mapping to date is considered and its potential use in other engineering geological applications is discussed. It is concluded that conditions are ideal for the use of the technique where the thickness of soil cover is relatively thin over most of the area mapped. It is also concluded that interpretative methods should be developed further in order that more complete use may be made of thermal infra-red linescanning for engineering geological mapping in South Africa.