6. Collins, S.H. 
Canada 
THE BLOCK ADJUSTMENT OF COLOUR 
IN HIGH-ALTITUDE PHOTOGRAPHY 
This paper describes a complete program of density calibration for colour and multi-spectral high-altitude 
photography. The central technique is a ‘block adjustment’ of colour, considered as a multi-dimensional 
variable, over a complete block of frame photography; in a manner analogous to the block adjustment of point 
location in analytical photogrammetry. The images of selected ground areas are located in the overlaps between 
frames and between flight-lines. The colours of these ‘pass points’ are used to determine correction functions 
for colour variations that occur within and between frames throughout the roll. The part of the sun-angle effect 
which is due to the nature of the terrain is suggested as a powerful discriminant for automatic 
photointerpretation. 
A method is also described for the absolute calibration of the whole block for ground radiance. The method 
is photographic, and it ties the radiance values to a great variety of known terrain and cover types on a regional 
basis. The value of this work in providing comprehensive ground truth for satellite imagery over a large region 
is discussed. 
3. Corten, F.L.J.H. 
Netherlands 
PERFORMANCE AND ECONOMY OF 
SURVEY FLIGHT SYSTEMS 
In a condensed review, the aerial photographic system is considered as a “black box” composed of aircraft, 
instrumental components, aerial cameras and other sensors, electronic guidance, photographic laboratories, 
survey flight and photography officers, and professional knowledge. 
Such units can be composed to meet general and specific mapping and planning tasks: performances are stated 
in terms of standard deviations, showing that good navigational and imagery quality is obtained also in 
difficult cases - large and monotonous areas, mountainous countries - in routine surveys. 
Efficiency of these systems is high, investments are relatively low; economy dictates the necessity of replacing 
conventional equipment by integrated survey flight and photography systems. 
8. Cruset, J. 
France 
THE PHOTOGRAPHIC MATERIALS, THEIR CHARACTERISTICS 
AND PROCESSING (FROM 1968 TO 1972) 
This invited paper deals with the photographic materials, as used in aerial photography, chiefly for 
photogrammetry and photo-interpretation purposes. The material's main characteristics, uses, processing and 
further exploitations are reviewed. This paper is based both on a very detailed questionnaire circulated by the 
author to some 80 experts and national reporters and on their answers, unfortunately not so numerous as 
expected, one dozen. Its main scope is, thanks to the collected informations and comments, to start a discussion 
on the various topics concerned at the Ottawa Congress. 
9, Dossi, S.W. 
United States 
COLOR (A REPORT) 
The use of color films for aerial photography has been the subject of debate and investigation for a number 
of years. This report continues these deliberations by discussion of the experimental and practical work of