addition, some of the equipment reported on has been in commercial use for considerably 
longer than the past four years. The remaining six replies did contain appropriate 
information and a summary of this material is included herein. 
SECTION IV. LITERATURE REVIEW 
To put some meat on the assorted bones (some very significant bones, to be sure) I 
received in response to our appeals, I made a systematic review of key North American 
publications, and a few others where pertinent materials might be found. I reviewed all 
issues from January 1968 to the present, of the following publications: Photogrammetric 
Engineering (technical papers and annual reports), Surveying and Mapping, Canadian 
Surveyor and Photogrammetria. The January 1971 issue of Bildmessung und 
Luftbildwesen, which was devoted entirely to the September 1970 symposium of ISP 
Commission II, was of considerable help. 
In addition, I reviewed the books of pre-published technical papers supplied by the 
American Society of Photogrammetry at their national meetings. It is noteworthy that of 
the 341 papers published by these meetings, only 23 concerned photogrammetric 
instruments of restitution. 
Also, I made two interesting observations in reviewing Sustaining Member annual reports 
in Photogrammetric Engineering. These are: 
a. At times Sustaining Members do not update their previous year’s report, even 
though they have good reason to do so. 
b. There are developments mentioned here which never are written up as technical 
papers, even though they should be. 
During the process of my literature review, I compiled a bibliography of all North 
American papers concerned, in general, with my subject. They are listed, alphabetically, by 
author, in the bibliography. Those papers which I specifically mention in my report are 
keyed by number in my reference list, in the order that I refer to them. 
SECTION V. SPECIFIC DEVELOPMENTS 
For ease in assessing total progress in the individual specialities, the items reported on 
are sorted into six (6) major categories, as follows: 1) traditional rectification, 2) 
mensuration, 3) differential rectification, 4) stereocompilation, 5) map revision, and 6) 
auxiliary items. Within these categories selected developments are generally cited in 
alphabetical order of the responsible agencies. 
1. Traditional Rectification 
Although traditional rectification, which removes the distortions of the aerial camera 
lens and recovers the orientation of the camera, had reached a high state of perfection in 
the World War II era with equipment such as the Zeiss SEG I, improvements are still being 
6 
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