GVII-38 
PHOTOGRAMMETRIC ENGINEERING 
The quality of the prints was moderately good, haziness at the borders often 
caused troubles. The photographs were too old (4 years) for experiments of this 
kind. 
During the last ten years more than a million square miles in British colonies 
have been covered by aerial photographs taken for the Directorate of Colonial 
Surveys with funds provided by the British Government. This photography is 
mainly intended for the production of 1:50,000 maps, but was mostly taken at 
a scale of 1:30,000 in the hope that the larger scale would be useful to other 
users concerned with interpreting vegetational, geological and soil details. Sev 
eral sets of the photo prints have been supplied for the use of such workers in 
the colonies. These photographs have been of great assistance to the Colonial 
Forest Departments. Many of them are still engaged in locating and assessing 
their resources; the 1:30,000 photos have also served well for reconnaissance 
work and for stock-mapping on extensive lines. 
Due to the difficult weather conditions, little photography has been taken so 
far over the tropical rain forest zones of West Africa and British Guiana; such 
as has been obtained has not proved of much help for forestry purposes. On the 
other hand useful separation of forest types can be effected on the 1:30,000 
photographs of Sarawak and North Borneo. As the aerial view concentrates 
attention on the forest canopy, the size and character of the tree crowns and the 
topographic site are the main criteria used in classifying the forests in those ter 
ritories. 
Throughout much of Central and East Africa the tree cover is associated 
with a ground flora of grasses, and varies in density from woodland with a 
closed, although light, canopy to open grassland with scattered trees. The many 
variations can be distinguished on the 1:30,000 air photos, which have been 
used both for forestry purposes and for general land use surveys. The latter type 
of work was pioneered in Central Africa by C. G. Trapnell, who in recent years 
has conducted an Ecological Training Scheme, which makes extensive use of air 
photo interpretation. 
For detailed forestry investigations the 1:30,000 scale is too small, and pho 
tographs of between 1:10,000 and 1:20,000 are required. Photography of this 
nature has been secured for special projects in some colonies where forestry prac 
tice is more highly developed. In Cyprus 1:10,000 air photos are available; 
their use has been described in the Forest Department’s Technical Pamphlet 
No. 17, “Classification of Forests into Crop Types and the Preparation and 
Interpretation of Stock Maps in Cyprus” by A. Polycarpou. Photographs at the 
mean scale of 1:15,000 have been taken for detailed stock-mapping in Kenya 
and British Honduras. In the latter project some experimental color photography 
was also taken from a height above ground of 7,500 feet; this revealed practi 
cally no detail not visible on high quality black and white prints; it may prove 
possible, however, to identify the distinctive color of mahogany and one or two 
other species provided photography is available at the appropriate season. 
Two projects at present being undertaken by Hunting Aerosurveys, Ltd. 
are concerned with forms of vegetation mapping. 
In the mountain area of Northern Iraq a forest survey was recently com 
pleted with two main purposes in view. The first was to assess the value to the 
Iraq Forest Department of the existing 1:40,000 air photographs covering the 
whole of the forest area. The second was to provide certain basic data on the 
forest types by making detailed enumerations of sample plots. Enlargements 
to 1:200,000, made to assist preliminary photographic interpretation, made