3. 
II. AEROTRI ANGULATION PROCEDURE 
Aerotriangulation using triplets consists of the following major steps: 
(A) Relative orientation. 
(b) Coordinate computation. 
(c) Triplet assembly. 
(D) Transformation to ground control. 
A more complete outline of each step follows. 
A. Relative Orientation 
The solution for relative orientation of the triplet in an arbitrary 
space coordinate system is performed by a rigorous least squares adjustment 
in which random errors in measured plate coordinates are minimized. This 
adjustment involves use of two types of condition equations: (a) the 
coplanarity or intersection equation which enforces the condition that rays 
from pairs of corresponding images intersect in space; and (b) the triplet 
equation which enforces the condition that rays from a triplet of corresponding 
images intersect at a common point. 
Derivation of these equations follows. 
1. Arbitrary Coordinate System and Initial Assumptions 
Let the consecutive photos in any triplet be designated i, j, k as 
illustrated in Figure 2.01. The arbitrary X, Y, Z triplet coordinate 
system has an origin at exposure station 0. and the X, Y, Z coordinate axes 
3 
are parallel to the respective (x, y, z)j, photo coordinate axes. For 
relative orientation of the triplet, photo j is placed in a fixed vertical 
position. The X-component of the air base 0. - 0. may be fixed at any arbitrary 
J 
quantity, X Qi . For example, the approximate base distance at either photo or 
terrain scale can be used and a comparable initial assumption can be made for 
X Qk (for this example let X Qi = 1.0). Assuming direction of flight from