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Increased use has been made of aerial triangulation by independent models, 
although the Zeiss Stereo-planigraph C8 is still used for some conventional 
aerial triangulation and aerial levelling work. Wherever the configuration of a 
project area allows, block adjustment methods are used for the production of 
minor control, for both planimetry and height, based, according to the specified 
accuracies, on a minimum of ground control. 
€ 
Since the installation of the equipment at the beginning of 1970, 
orthophotographs and photomaps have been in continuou production at scales 
ranging from 1:1000 to 1:50 000 (166, 188). The planning required for this is 
fairly complex and a considerable effort has been made to optimise the methods. 
Estimating for orthophoto production is also a complex operation and a computer 
program has been written and developed in order to ensure the optimisation of 
all the variables involved. À particular innovation has been the use of a light 
helicopter to carry a Wild RC8 152 mm survey camera and photographer for 
taking vertical aerial photography at contact scales as large as 1:500. 
Photogrammetric measurement of such photography, taken over areas of hard 
standing, has been carried out and results show that consistent photogrammetric 
heighting can be achieved within an accuracy of +10 mm to +15 mm standard 
error. 
A terrain modelling section has been established within the Mapping Division, 
using a Fairey-Packman machine. Very accurate models are cut from solid 
blocks of polyurethane, using contour terracing methods. 
GLASGOW UNIV ERSIT Y. Dept. of Geography 
Research has been carried out into the application of photogrammetry to 
urban studies and planning, including the development of a perspective plotting 
system, (110) and numerical photo-interpretation keys for use with multi- 
discriminant analysis in the computer (109). 
Testing of the accuracy and quality of orthophotographs taken at a variety of 
scales over different types of terrain has been undertaken in co-operation with 
various organisations in different countries. Investigations into improved 
methods of digitising photogrammetric measurement have been made in 
co-operation with various electronics firms. 
An improved method of heighting from parallax measurements using a 
computer solution for derivations of the correction parameters has been 
developed. (118) Other computer programs for the computation and adjustment 
of analytical and semi-analytical aerial triangulations, grid tests and so on, 
have been devised and written. A suite of programs written in AIGOL for the 
location of roads and computations of earth-work volumes through a digital 
terrain model has also been developed. 
HATFIELD POLYTECHNIC. Dept.of Civil Engineering and Construction 
Investigations into the stability of chalk slopes are being undertaken using 
photogrammetric methods and research is being carried out into the use of 
colour, infra-red, multispectural, and linescan imagery in fields of soil 
identification and mineral exploration, also into the use of digital ground models 
in connection with highway design projects.