: eoo 
Some research is taking place at one of the private companies of 
connecting three stereoplotters and one stereocomparator directly on- 
line to a computer. This to prepare data for an off-line unit atfached 
to the Calcomp 718 flatbed plotter. 
COMMISSION 111, AERIAL TRIANGULAT ION 
  
  
RAPPORTEUR: . Dr. P.R.J. Boniface 
Much activity has taken place over the last four years and many thous- 
ands of overlaps have been bridged and put into block adjustment. The 
National Mapping Agencies of both Rhodesia and the Republic of South 
Africa and the larger private companies use a variety of aerótriangul- 
ation methods continuously. 
In Rhodesia large blocks are bridged on the Nistri Stereocomparator. wi th 
block adjustment by a direct solution method. The National Mapping 
Agency in the Republic of South Africa undertakes the bulk of their 
bridging of approximately 3 000 models per year on a Zeiss PSK Stereo- 
comparator supplemented by a Wild AIO and a Wild A7. The block adjust- 
ment is based on the Amer principle. One private company uses the Wild 
Stereocomparator and adjusts the block by the Anblock direct solution. 
Recently a block of 2 100 models was adjusted in thirty-five minutes 
using this method. 
| 
Two members of the Society attended the Symposium of Aerial Trianaulation oe 
in London in August, 1971, and presented papers. Mr. H.5. Williams on 
"Analytical Aerial Triangulation by Trilateration Microscope" and Dr. 
P.R.J. Boniface on "Recent research into Block Adjustment Methods at the 
Aircraft Operating Co. (Pty) Ltd." 
COMMISSION IV. MAPPING FROM PHOTOGRAPHS 
  
  
RAPPORTEUR: Mr. P.W. Thomas 
With the basic |/50 000 Topographical Map of South Africa nearing complet- 
ion (now over 90%) the 1/10 000 scale has been adopted to supply the need 
in developing areas. The Orthophoto map appears to be the most convenient, 
popular, economic and rapid method to use in such densely developed areas. 
Geographical sheet lines of 3' by 3' have been adopted for the series and 
to date some 300 sheets have been produced using 1/30 000 photography. 
Two members of the society presented papers at the International Symposium 
on Orthophoto Mapping in Paris in October, 197| -.E.G. Buckley on "Recent 
Trends and uses of Orthophoto Maps in the Republic of South Africa" and 
K.J. Lester on "The South African 1/10 000 Orthophoto Map Series". 
In Rhodesia the National Mapping agency has completed the 1/50 000 series 
and is now busy with revision and preparing a |/5 000 series of developed 
areas. 
  
The nineteen. commercial operating companies undertake mainly the large 
scale surveys for road and engineering works for consulting engineers and 
local authorities plus contract work for the National Mapping Agency at a 
scale of 1/50 000 and 1/10 000. The Provincial Roads Departments and 
Municipalities also undertake large scale work to scales of 1/1 000 and 
sometimes 1/500.