INTRODUCTION 
To date most photogrammetric measurements have been based on the 
geometry of a single photograph or that of a stereopair. The 
measured quantity is usually deduced from a number of observa- 
tions taken from only one photograph or one stereopair; there is, 
therefore, a high degree of uncertainty regarding the accuracy 
of measurements. 
Since highly accurate measurements are of paramount importance 
in some engineering and industrial measurement problems, it was 
decided to develop a close range photogrammetric system which 
would reduce the degree of uncertainty and improve the accuracy 
of the resulting measurements. 
In developing such a system the following points were taken into 
consideration:- 
1. that the system should be a versatile one, to be used for 
stereo as well as multi-stereo. 
2. that the system should be easily adapted for the normal as 
well as the general case of close-range photogrammetry. 
3. that the assembly of the data acquisition system and its 
operation should be simple and the apparatus, if possible, 
portable. 
4. that mathematical expressions should be derived for both 
the normal case and the general case using a strong geo- 
metric representation for the data reduction system. 
5. that a special test board should be designed and precisely 
constructed, so that a comparison could be made between the 
results obtained from the stereo and multi-stereo systems. 
It is obvious that in order to satisfy the above requirements, 
a multi-station system should be employed. Such a system has 
already been reported in general terms by Kenefick (1971) and 
its accuracy has been referred to by Hottier (1976). Granshaw 
(1980) also described the application of the Bundle method to 
multistation photography. He concluded that such a combination 
can provide high and homogeneous precision. Most recently 
Atsushi Okatomo (1981) reported the results of his work on 
Model Construction Theory with multiple photography. His work 
was based on the mathematical basis (Okatomo 1981 Part I) of 
the general orientation problem of a stereoscopic pair of 
photographs. 
The system described in this paper is based on four stations 
only, has the advantages of being economical, reliable, port- 
able and practicable for its close range applications. The 
results of the system not only confirm the work done by the 
previously mentioned authors, but also show. that in practice 
the accuracy is generally improved with its highest value in 
the dimension parallel to the camera optical axis. 
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