Theodolite 
à image axis 
  
  
Theodolite 
image 
- — em 
  
  
  
Theodolite 
horizontal 
circle 
A 
UJ 
N 
Figure 2 - The relation between theodolite image coordinates 
(x and z) and the horizontal direction o and the 
vertical direction f. 
tan (90 - à, + a) 
tan B/Cos (90 - ag + a) 
Where 
other 
ag is the horizontal direction of the 
theodolite station. 
The main 
are: 
advantage of the theodolite images 
No need for development and processing for 
theodolite image. 
No need for comparator to measure the theo- 
dolite image co-ordinates which are obtai- 
ned from the measured vertical and hori- 
zontal directions. 
No limitations on the depth of focus, the 
format size and the intensity of light for 
the theodolite image. 
Generally, the accuracy of the theodolite 
image co-ordinates are much better than a 
photographic image co-ordinates. A one- 
111 
"second theodolite gives an accuracy in the 
x and z co-ordinates of t 0.5 microns for 
a 100 mm principal distance. 
Four out of five relative orientation para- 
meters of the two theodolite images are 
known and having zero values. 
A sample of the horizontal and the vertical 
directions taken from theodolite two stations 
(left and right) and their corresponding theo- 
dolite image co-ordinates for principal dis- 
tance of 100 mm, is given in table (1) and (2). 
Relative Orientation 
The used instruments and the required measure- 
ments for calculating the co-ordinates of the 
two theodolite images have been given. Also 
the orientation parameters of each theodólite 
image have been discussed. Investigating the 
orientation parameters of the two theodolite 
images one finds that: