CLOSE-UP STEREOPHOTOGRAPHY 
USING A SINGLE CAMERA 
Gunnar Simonsson 
Department of Photogrammetry, Stockholm 
Stereoscopic photography of fixed objects 
using a single camera can be performed in 
accordance with any, for instance the normal, 
case by moving the camera from the one base 
point to the other between the two exposures. 
The method has long been used for instance 
with photo-theodolites. For the stereoscopic 
viewing of the photographs there are no 
stringent requirements placed on the relative 
orientation of the camera. For photogrammet- 
ric measurements, however, it is necessary 
to know or to be able to reconstruct the 
relative orientation. 
In comparator photogrammetry combined with 
data processing the relative as well as the 
absolute orientation can be calculated using 
y-parallaxes and control point co-ordinates. 
This method is excellent for the numerical 
determination of points but is not practical 
for graphical evaluation (for instance the 
drawing of contour lines and sections) due 
to the great demand it places on equipment 
and soft-ware. Therefore, in production 
graphical work is usually performed in an 
analogue instrument, such as the wild A7. 
To achieve efficiency and good economy in 
graphical photogrammetry using analogue 
instruments one fundamental requirement is 
that the stereo-camera (or the device holding 
the single-camera) should be stable enough 
to guarantee the same relative orientation 
from the one stereo-pair to the other. 
  
  
In order to make the fulfilment of this re- 
quirement meaningful the two photographs must 
be adjusted very accurately in the photograph 
holders of the instrument, with respect to 
the inner orientation. 
To achieve this accurate inner orientation of 
the photographs, a special photograph adjust- 
ing device is needed, this device being placed 
in the photograph holder of the stereo instru- 
ment. 
With the conditions above fulfilled the one 
Stereo-pair after the other can be oriented 
.in the instrument with practically no change 
in the orientation elements. Practical expe- 
rience has shown that the only adjustment 
needed is a slight change of elements to ob- 
tain correct distances in the direction of 
the camera axis. This "convergence adjustment" 
can be done either by adjusting $ of one of 
the projectors or by moving the photograph 
in the one photograph holder in the x-direc- 
tion using the photograph adjusting device. 
Which method should be used cannot be stated 
generally, and is not of great practical im- 
portance as the adjustment needed is very 
small. 
To accomplish the "convergence adjustment" no 
known distances are needed if the camera base 
is constant and a bar with two marks, distant 
from each other by the length of the base, is 
placed parallel to the base and photographed 
at the same time as the object. The discre- 
pancy in distance in the direction of the 
camera axis is eliminated with the base of the 
stereo instrument set at zero. 
Any photograph from a camera with a stable 
inner orientation can be adjusted in the 
photograph holder with an accuracy sufficient 
for most practical purposes, even with no or 
defective fiducial marks. With the first 
Stereo-pair oriented in the instrument the 
co-ordinates of the fiducial marks (or any 
identification marks or patterns in the photo- 
graphs) are recorded and used for the adjust- 
ment of the succeeding stereo-pairs with the 
aid of the photograph adjusting device. If 
the photographs are oriented in k as a first 
step only one fiducial mark is needed in each 
photograph to reconstruct its position in the 
photograph holder. 
DESCRIPTION OF THE DEVICE FOR 
CLOSE-UP STEREOPHOTOGRAPHY 
WITH A SINGLE CAMERA 
Single camera stereophotographs with a good 
stability with respect to relative orienta- 
tion can be taken at the Department of Photo- 
grammetry with a camera mounted in a camera 
holder designed and constructed according to 
the principles shown in Figure 1. 
The camera is placed unsymmetrically on a 
frame with four legs (C-Al, C-A2, D-Bl, D-B2 
in Figure l1). The legs fit accurately into 
four holes in a stable base, as is illustra- 
ted by the dashed arrows. For one of the 
camera positions the legs C-Al and C-A2 are 
fitted into the holes 1 and 2. For the other 
camera position the legs D-Bl and D-B2 are 
fitted into the same holes. (The other camera 
position is dashed in the figure). The photo- 
graphy base can be varied. It is double the 
distance from the camera to the center of the 
camera holder. A flash lamp or a photo-flood 
lamp may be placed in the center of the hol- 
der as shown in Figure 1. 
The camera axis will be reconstructed with a 
high precision from one exposure to the other, 
firstly, because of the great distance between 
the holes and, secondly because of the nature 
of the framework of the holder, which, assu- 
ming the base frame is stable, is itself a 
stable structure. This further means that 
only slender members are required for the 
frame which theoretically need only be pin-