J. J. THERRIEN 
A Simultaneous Section Adjustment for Small Computers 
The horizontal section adjustment is a very powerful tool for extending control over 
wide areas. The solution outlined is designed for smaller computers ; it makes it possible to 
perform the simultaneous adjustment of a large block of sections with a fraction of the storage 
requirement of the direct numerical solution. The most popular block adjustments in use at the 
present time are, adjustment of strips by polynomials, the Jerie Analogue method, and the nu 
merical section adjustment. The simultaneous section adjustment of a block of reasonable size 
has so far been confined to large computers. The method outlined in the paper permits us to per 
form this adjustment on a small computer without compromise in ease of data handling and wi 
thout restricting the flexibility of the simultaneous section adjustment. 
This article gives the theory behind the solution and an outline of the computer pro - 
gramme. 
J.M. ZARZYCKI 
Emploi en aérotriangulation des indications combinées du statoscope, de la chambre 
d'horizon et du système de navig at ion Do ppler. 
ETATS-UNIS D'AMERIQUE 
James ANDERSON 
Triplets : a basic unit for analytical aerotriangulation 
A method of analytical aerotriangulation to be applied to strips of photography is de - 
veloped in which the triplet is used as the basic unit. The procedure consists of : (a) Relative 
orientation of individual triplets in arbitrary orthogonal coordinate systems ; (b) determination 
of triplet coordinates in the individual arbitrary coordinate systems ; (c) triplet assembly ; and, 
(d) transformation to ground control. 
Relative orientation is accomplished using a rigourous least squares adjustment re - 
suiting in residuals that are applied to the photographic coordinates of each point employed in 
the triangulation. Corrected plate coordinates are then used to compute adjusted point coordi 
nates in the individual triplet coordinate systems. Triplets are assembled with a linear three 
dimensional coordinate transformation. Transformation of points in the arbitrary system to 
ground positions is accomplished by higherdegreee three-dimensional coordinate transforma 
tions. 
The method of aerotriangulation is being programmed on the CDC 1604 electronic 
computer which has a 32, 000 11-digit word storage capacity. Tests with fictitious photography 
will be used to verify the theoretical accuracy of the method. 
Robert B. FORREST 
The Analysis of Orientation Element Differences to Investigate Error Causes in 
Aerial Triangulation 
If the true errors of the orientation elements of a strip of aerial photographs are 
known, true aerial triangulation error propagation curves for each element can be obtained from 
the orientation elements recorded during triangulation. 
The true positions and attitudes of each photograph in a strip of 37 were accurately deter 
mined from known ground control points, using analytical orientation techniques, à least squares 
solution, and a digital computer. Aerial triangulation of the same strip was performed several