n— s 
148 RELATIVE ORIENTATION IN MOUNTAINOUS TERRAIN, VAN DER WEELE 
The influence of this term can be corrected by methods similar to those given for Aw in 
the case of vertical photography. 
For example, one possible procedure may be stated as 
  
  
  
  
  
  
  
  
  
follows: 
3 ge 1. Eliminate the errors in and b, in the normal way. 
\ 
*/ A 2 Pp 
p" 
5 6. A 
7 7 „m 
: x x, X 
Fig. IILa. Fig. III.b. 
2. Make p; — 0, using the chosen « rotation (See fig. IILa.) 
3. Make p, — 0, with x'. Read x^. 
4. Make p, — 0, with x'. Read x',. 
5. Set x" on another value. 
6. Repeat steps 3 and 4. Read x’, and x',. 
7. Construct a graph, as in Fig. IILb., where p' — x', — x',, and p" — x', — x's. 
8. Read (at A) the correct value for x', and introduce this in the instrument. 
9. Make p, — 0, with x". 
On the principles treated in Section II, and illustrated in the above example, a great 
number of variants can be based, adapting the procedure to the special features of the 
instrument, or to the inclination of the operator. A numerical solution, similar to that 
treated by Dr. H. G. Jerie in Photogrammetria No. 1, 1953/54, can be used with advan- 
tage. The same formulae may be applied if, as a first solution, the pseudo elements AA*, 
4B* etc. are solved. The real elements may then be computed from equations (IIL1), 
according to the choice of elements which has been made. 
IV. Oblique photography. 
The parallax formula for oblique photography can be written in a similar form to 
that of equation (IL.2). As an example, assuming that the c-axis is primary, the formula, 
for the elements of the left projector, reads: 
Y? + Z? X 
=p, 7 Ao! — Z (Y eos o t Z sino) Ag' t- Ab, — 
Y X 
Z Ab. + Z (Y sin o —Z cos o) Ax' 
which may be re-grouped as follows: 
XY Y? + Z2 Y 
eo 7 (—4q' eos o + 4x’ sin w) — Z [o^ zi Z 1b, 
+ X (—4A49' sin o — Ax' cos o) d b 
XY Y2 + Z2 
or: —p, = 7 AA** — Z |B** — Z iC XAD** -- AE