DIRECTORATE OF MILITARY SURVEY, Ministry of Defence 
The Directorate of Military Survey employs photogrammetric methods to map new 
areas, and to revise out of date mapping in support of operational and training 
requirements. The plotting of new contoured sheets at 1:50 000 and larger scales 
has been undertaken using Wild A8 and B8 instruments. Analytical aerial 
triangulation was carried out by means of a Zeiss (Jena) Stecometer, or by 
independent models using a Wild A8 or B8S with tri-axis locator and EK8. 
Sparsity of control and poor point identification still pose the major problems in 
aerial triangulation (95), but new computational adjustment techniques which 
allow the use of minimum control have improved the situation. In addition to 
instrumental work, numerous graphical tasks have been completed including 
photomapping, minor control plotting and rapid revision of out of date mapping 
using both survey and non-survey aerial photography. The introduction into 
service of the Williamson F49 Mk IV camera has resulted in improved standards 
of photography in terms of both accuracy and resolution. 
DIRECTORATE OF OVERSEAS SURVEYS, Ministry of Overseas Development 
The Directorate of Overseas Surveys assists developing countries in basic land 
surveying and mapping. It has continued to produce new and revised topographical 
mapping by photogrammetric methods for countries in Africa, the Middle East, 
the Far East, the Pacific, the Caribbean and Central America and for the British 
Antarctic Survey. 
Requests for large scale mapping of specific development areas now exceed 
those for 1:50 000 mapping. In 1973-74, for example, maps at scales of 1:1250, 
1:2500 and 1:5000 accounted for nearly two-thirds of those produced by photo- 
grammetry (149). Nearly all the large scale map series are contoured, with a 
vertical interval of either 10 ft or 2. 5 m; the contour plot is screened and 
combined with the detail plot in positive form so that diazo copies can be made as 
required. Plots showing selected features only were produced to assist a 
cadastral survey project. 
564 contoured 3© sheets of 1:50 000 mapping were produced during the period 
under report (18, 126). Contour intervals were 25 ft, 50 ft, 100 ft, 20 m and 
40 m according to the type of country and its views on metrication. The smallest 
scale basic maps produced photogrammetrically were the 1:250 000 series of 
Antarctica plotted from tricamera photography (136, 137) (see Section 3 of this 
Report). 
The photomapping techniques described in the 1972 report were developed and 
improved to give better distinction between vegetation categories and to reduce 
the number of printing colours required. Photomaps were produced at scales of 
from 1:2500 to 1:125 000, in addition to the regular series at 1:25 000 and 
1:50 000. The photomap is not considered to be economic for developing urban 
areas, but has proved to be very successful in areas such as semi-desert and 
swamp where natural features and vegetation dominate the landscape (47, 116, 
128). The latest experiment combines a photomap sea plate (showing off-shore 
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detail) with a line map of the land. 
The first 1:250 000 planimetric maps using LANDSAT-1 imagery as a monochrome 
photobase were produced for part of Antarctica: the imagery was fitted to ground 
control where available and the graticule extended across the mapping block (137).