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BRITISH NATIONAL REPORT 5 
A standardised method of testing plotting machines has been drawn up and is now in 
regular use. 
A small proportion of all types of air survey work is checked in the field by instrumental 
surveys in order to evaluate the standard error of the survey. A comparison of costs is also 
made with ground survey methods to ensure that the most economical method is used. 
THE DIRECTORATE OF OVERSEAS SURVEYS. The Directorate has developed a technique 
for photogrammetric bridging using a pair of multiplex projectors fitted with inclinometers 
(18). The inclinometers have been made by Messrs. Hilger & Watts Ltd. and the method 
is now in production use at the Directorate. A considerable amount of experimental work 
has been undertaken with the Airborne Profile Recorder (6) and other systems using the 
recording of statascope data. This work continues. New methods of hill shading and 
processing contact prints have been developed. The Directorate has also been interested 
in the performance of photographic films and has undertaken experimental work in this 
connection. Various plotting machinery has been tested and small trials have been under- 
taken with the Jerie analogue computer (12). 
THE WiLLIAMSON MANUFACTURING CoMPANY LiMITED have now produced a Mark 2 model 
of their L.S.P. Plotter. The plotting on this model is carried out direct on to a slate table 
using a modified Williamson Multiplex Tracing Table. 
The increasing demands for distortion-free lenses have been met by issuing a new Mark 3 
version of the well tried F.49 survey camera fitted with a Ross distortion-free lens of 12 inch 
focal length. 
A new model of the Multiplex diapositive printer has been introduced with a removable 
optical head so that the printer can be used with various cameras, interchangeable heads 
being provided to accommodate the different types of survey camera lenses available. 
UNIVERSITY COLLEGE LONDON. Theoretical investigations resulting in rigorously exact 
formulae for relative and absolute orientation have been completed (10, 14). 
The problem of relative orientation, which involves the determination of the elements of 
at least one orthogonal matrix, has been solved by expressing the matrix in terms of three 
independent parameters that appear in a rational algebraic form and using it to set up an 
equation expressing the relative orientation condition. À set of such equations, which are 
of the third order in five unknowns, may be solved by a rapidly converging process of iteration. 
The problem of absolute orientation, which involves the explicit determination of the 
rotation of the space model, has been reduced to the solution of linear equations in three 
unknowns. The simplicity of the solution has arisen from working in the complex plane 
instead of directly in three dimensional space. It may be of value in aerial triangulation by 
the method of independently observed models. 
Work is proceeding on arithmetical methods of adjusting blocks of aerial triangulation 
with planimetry separated from heights, and also with the two simultaneously. The Mercury 
computer is being used for this work. 
5. Technical Education 
(Education Technique) 
(Technische Erziehung) 
UNIVERSITY COLLEGE LONDON (Department of Civil and Municipal Engineering) is 
engaged at a postgraduate level in teaching the principles of photogrammetry and their 
application in practice. To this end, a course taking up to twelve students and of a year’s 
duration has been arranged. The courses have been running for six years and include the 
following subjects:— 
Theory and Practice of Aerial Photography 
Photogrammetric Theory 
Simple Plotting Methods and Map Revision 
Theory and Development of Plotting Machines 
Analytical Methods 
Aerial Triangulation 
As well as this postgraduate teaching a certain amount of teaching of photogrammetry 
is given to students of the Civil Engineering, Geography, Geology and Town Planning 
Departments of the College. 
Research work at a postgraduate level is also carried out by individual students within 
the Department—these researches frequently leading to a degree of Doctor of Philosophy 
or Master of Science. 
Since the last Congress much practical work has also been carried out on the Thompson- 
Watts plotting machine in order to establish the best method of doing aerial triangulation. 
THE SCHOOL OF MILITARY SURVEY trains military officers and other ranks in the survey 
duties required by the Directorate of Military Survey. Overseas Surveys students also 
attend courses at the School before taking up their posts. 
The Long Survey Course for officers and overseas students lasts for fourteen months and 
includes training in the theory and practice of photogrammetry.