UPDATING PROPROSAL 
ON 
SPECIFICATIONS FOR AIR PHOTOGRAPHY 
Proi. Ir. Frangois L.J.H. Corten 
Dipl.-Ing. Rudolf W. Lorenz 
ITC 
HISTORY 
During several decades, many "Specifications for aerial photography" have been collected, combined 
and copied from parts of Specifications which were made for other purposes. Often, then, the totality 
of the document was inhomogeneous not only, but even contradictory in itself, giving rise to conflicts 
between producer and client or user. 
This has been recognized by the British Air Survey Association (BASA) - as producers of aerial 
photography - and by ITC - serving as checking agency for government clients or users of the photography, 
or serving as arbiter in cases of conflicting opinion. 
The BASA has taken the initiative and has gone through the trouble to compile a set of "Specifica- 
tions for vertical Air Photography". This has been adopted and published by the Royal Institute of 
Chartered Surveyors (RICS). 
At the International Congress of the ISP, at Hamburg, 1980, it was suggested that Commission I 
might update these Specs in order to arrive at an agreement as broad as possible, with the aim to have 
them accepted by the ISP at the Rio Congress in 1984. 
PURPOSE 
The "Specification for vertical aerial photography" aims to define the desired qualities of the 
photographic product rather than to describe the methods, ways and means of production. 
It is intended for general use worldwide. 
It aims to define aerial photography of good standard which can be achieved in practice. 
Specifications for aerial photography shall be really "specific" so as to avoid any misinterpretation 
and misunderstanding. 
On the other hand, they should be as simple as possible so as to leave the producer free in his choice 
about how to produce the desired result. 
FACTORS AFFECTING TIME, EFFORT AND COST OF PHOTOGRAPHY 
The Specification is designed to satisfy the needs of most clients and users of black and white 
photography and includes, therefore, some optional and alternative clauses, which may be selected as 
required. Also clients or users may wish to make their own additions and deletions to suit particular 
requirements. 
These options and alternatives should not be used in an attempt to aim at perfect photography. 
"Perfect" aerial photography does not exist as - in the chain of optical-physical-chemical stages 
from the object until the photographic product - each of these stages induces a degrading effect on 
image quality. 
It is logical, however, to aim at aerial photography which is most efficient for the required purpose 
and end product, and no more than that. Any constraint which is imposed on the producer will lead to 
unduely larger effort, production time and cost. 
Examples: 
- Specifying "cloudless" photography instead of allowing a maximum of, say, 3Z cloud aggregate may 
- in certain climates - lead to standby weeks doubling the period of photography. 
- Limiting the minimum or the maximum of solar altitude beyond necessity may have a similar effect. 
It is therefore suggested that the options shall be considered positively by the client to arrive at 
the photographic and mapping production in the most efficient way. 
UPDATING 
ITC - after having used the RICS Spec's in various instances - feels that usefulness can be increased 
by making them more user-oriented and presents an updated version. 
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