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MEASURABILITY AND INTERPRETABILITY OF PHOTOGRAMMETRIC DETAILS * 
  
A/Prof. J. C. Trinder 
School of Surveying 
University of N.S.W. 
SYDNEY, AUSTRALIA. 
Abstract 
This paper presents a review of the results of research on the 
visual tasks of measurement of coordinates, and the interpretation of 
photogrammetric details. The accuracy achieved by the task of poin- 
ting to symmetrical objects, and asymmetric objects eg. edges of 
details are discussed, and an attempt is made to relate visual per- 
formance to physical characteristics of the photographic image. A 
discussion is given on the problem of assigning weights to photogram- 
metric coordinate measurements as a function of point location, and 
therefore imaging quality of the photogrammetric system. 
The distinction between the visual tasks of object detection 
and object recognition and hence interpretation is emphasised and a 
review is made of some current research results on the interpretation 
of photographic details related to image quality. 
1. Introduction 
The impact of pointing precisions and accuracies on the overall 
accuracy of photogrammetric processes has gained increased significance 
as the capabilities of photogrammetric measuring equipment have 
improved. Indeed, the precision of stereocomparators and analytical 
plotters, now of the order of 0.5 to lum approaches the highest 
precisions which can be achieved by human observers. Pre-marking of 
all ground points, including pass points, has become a regular proce- 
dure in photogrammetric operations, in order to improve the accuracy of 
pointing to identifiable images of ground points. Bundle methods of 
block adjustment with additional parameters have now made it possible 
to obtain accuracies of coordinates after adjustment of Sum or better. 
* Paper presented to I.S.P. Commission I Symposium, Tokyo, 1978. 
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