THE NATIONAL REPORT OF THE PHOTOGRAMMETRIC SOCIETY OF SOUTH 
AFRICA TO THE 13TH CONGRESS OF THE INTERNATIONAL SOCIETY OF 
PHOTOGRAMMETRY COVERS DEVELOPMENTS THAT HAVE TAKEN PLACE 
SINCE THE 12TH CONGRESS IN OTTAWA, CANADA, 1972. 
This report has been compiled by the Council of the Photogrammetric 
Society of South Africa. It includes information supplied from its 
Rhodesian Branch. 
COMMISSION 1. PRIMARY DATA ACQUISITION 
  
RAPPORTEUR: Mr. G.E. Belling 
1. Remote Sensing and Multispectral Photography 
  
1972-5: Establishment of the first commercial company in South Africa 
dealing with Multispectral Photography for geological exploration and 
vegetation studies. Spectral Africa (Pty) Ltd., commenced operations 
with a four—window multispectral camera and supplemented this equip— 
ment subsequently with an RS 25 T.I. Thermal I—R Line Scanner. 
2. Camera Calibration 
Full calibration facilities have been established at Natal University, Durban, 
under the direction of Professor D. Scogings. 
3. Airborne Photography 
  
Six commercial companies offer aerial photographic services for mapping 
and non—mapping uses. This photography is at a variety of scales ranging 
from 1 : 2000 to 1 : 50 000. 
National small scale photographic coverage during the past four years can 
be summarised as follows: 
1972-5 1:36 000— 1 : 75 000 approx. 740 000 km? 
1972—5 1:20000— 1 : 36000approx. 136 000 km? 
. Processing and Photographic Equipment 
  
Several automatic processing units (for both black and white and colour) 
have been acquired during the past four years by commercial organisations. 
Wide and Superwide angle cameras in commercial use now exceed 14 in 
number and have been used for panchromatic and |—R photography as 
well as colour and colour |—R. 
COMMISSION Il. INSTRUMENTATION FOR DATA REDUCTION 
  
  
RAPPORTEUR: Mr. D.S. Clegg 
In the field of design and construction of instruments, a Monocomparator has 
been produced at the University of the Witwatersrand. Designed by Dr. H.S. 
Williams, and called the Trilateration Microscope, this was built primarily as a 
research instrument and comprises essentially a light box, a simple glass bridge 
which carries the diapositives, plus a glass measuring scale and two microscope 
readers all housed in a very light frame. It can be operated from a table top, 
as the trilateration technique makes it unnecessary to have a rigid stable frame 
as a measuring reference system, and can provide plate co—ordinates to sub— 
micron accuracy.