COMMISSION VII. INTERPRETATION OF DATA 
RAPPORTEUR: Mr. T.C. Partridge 
Introduction. Activities in photo interpretation and remote sensing over the 
last four years may conveniently be divided into three categories: those 
employing locally available commercial techniques, those making use of 
satellite imagery, and those oriented towards the development and refine— 
ment of new local applications. 
1. Conventional Techniques 
  
Fields of activity which have received special emphasis are geofracture map— 
ping as a precursor to computerised analysis for the evaluation of super— 
ficial and buried structures, and engineering geological interpretations as an 
aid to assessment of the suitability of sub—foundation materials for all new 
Township development in the Transvaal. A provincial Ordinance making 
mandatory such prior geological investigations was promulgated early in 
1974. An important milestone in systematizing the applications of air 
photo interpretation to terrain evaluation for all aspects of physical plan— 
ning was the Third Symposium on Terrain Evaluation in February 1975. 
Among the important applications discussed at this meeting were the uses 
of air photo interpretations as an aid to the selection of optimum transport 
corridors, in deciding on the most advantageous land—use zonings in urban 
and regional planning, and in compiling the two important natural resource 
inventories currently being prepared by the Soils & Irrigation Research 
Institute of the Department of Agricultural Technical Services. 
Other important applications in the planning field have been in the pre— 
paration of environmental absorption and impact statements prior to the 
alignment of new national roads, the evaluation of terrain and engineering 
geological constraints governing the future development of the Witwaters— 
rand Metropolitan Complex, and in the design of a freeway network and 
open—space system for the next 50 years in the Pretoria—Witwatersrand— 
Vereeniging area of the Southern Transvaal. 
Specialist use is also being made of imagery of more limited spectral band 
width, particularly in the infra—red range. 
. Satellite Imagery 
The interpretation of ERTS 1 imagery in South Africa has been co-ordinated 
by Dr. O.G. Malan of the National Physical Research Institute, who is a 
NASA—ERTS Principal Investigator. General Conclusions which have 
emerged from the interpretation of the ERTS imagery to date are: 
(1) “ERTS imagery can be phased into the current programmes of survey 
agencies as an additional data base without major problems. 
(2) ERTS imagery has provided a major data base and/or impetus for at 
least two projects: the first detailed tectonic and geomorphological 
maps of the Republic of South Africa. 
Resource Management: The following are some of the projects in 
which the interpretation of ERTS imagery has been successfully 
applied in South Africa: 
(i) the preparation of a vegetation map of the Eastern Cape; 
(ii) the preparation of a regional land—use map of the Gamtoos 
River Valley; 
(iii) an analysis of vegetation degradation in the Eastern Orange Free 
State in particular the invasion of grassland by dwarf scrub 
communities; 
(iv) an analysis of the chief structural geological elements of the 
Transvaal;