9 
dm 
3.3. THREE-DIMENSIONAL TEST OBJECTS 
In the non-topographic applications of photogrammetry one very often has 
to use cameras in which the interior orientation is unknown. The cameras are 
usually focussed at short distances. In order to calibrate such cameras the 
author in 1964 performed his first experiment with a three-dimensional test 
object, Fig. 1. The calibrating technique is described in [29] and [33]. An 
example is given in [30], where a three-dimensional test object was produced 
by translating a glass grid. See also chapter 8.2. 
Kaasila [20] has developed a similar technique for calibrating projectors of 
stereo-autographs Wild A7 and A8. In 1966 Harley [17] describes a method 
for calibrating close-up cameras by photographing three-dimensional arrays 
of targets, but no examples are given. Also Gelhaus [9] has used a similar 
technique.