The introduction of artificial parallaxes to produce stereomates is 
only possible in the direction of the profiles (i.e. forward or 
backward), therefore the direction of the profiles should agree with 
the flight direction (within a few grades). 
The geometric correction for regularly distorted images is acm 
present only by affine transformation. In future it will be extended 
up to a third degree polynomial correction. 
Operational considerations 
A standard OR-1 (also the ITC version with the present program 
"ORI") requires input from a magnetic tape. It consists of an iden- 
tification number, the scan length, the slit width, the photocoord- 
inates of three orientation points and the "image profiles". "Image 
profiles" are a list of photo coordinates of those points which 
should be imaged at 1 mm intervals along the scan lines in the 
orthophoto. 
Such tapes can be produced directly by scanning stereo models in a 
photogrammetric plotter which is specially equipped for this purpose 
with a tracking system and a recording device for photo coordinates 
(e.g. WILD PE3 + PBKIl [ 4PAZI ]). The recorded data can only be used 
for the production of an orthophoto with fixed scale and fixed slit 
size from one specific photograph. Stereomates can not be made with 
. this system. The area must be re-scanned to produce an orthophoto 
from a different photograph or with a different slit size or at a 
different scale. 
Another way to produce the required input tapes is to use a digital 
computer to convert any height information into the necessary "image 
profiles". There are programs available for the production of ortho- 
photos, stereomates and other kinds of geometric image transforma- 
tions, e.g. the SORA programs [31.14]; To find the transformation 
parameters these programs require (amongst other data) photo coordi- 
nates of control points. These coordinates can be measured directly 
in the new Wild version of the OR-1. Subsequently the data must be 
transferred to a computer provided with the SORA programs. To be 
able to abandon the empirical orientation of the photograph, the ORI 
must be left idle until the SORA processing is ready and the 
magnetic tape is transferred. Then the production on the OR-1 can 
start. 
There is no time lack between measurement of the control points on 
the OR-1 and production of the orthophoto (or other product) in the 
ITC approach. The measurement of up to 10 points does not take 
longer than an empirical orientation. This is because prepositioning 
is done by the computer after the measurement of the first two 
points. Only very small manual corrections are required after the 
third or fourth point if there were no blunders in the first 
measurements. Blunders can be eliminated interactively. 
For perspective, affine or polynomial image transformation the 
computations are very easy and therefore an external computer is not 
needed. All the system needs is a ground control file, measurements 
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