PREFACE 
The 1971 Symposium of Commission III of the International 
Society for Photogrammetry was held at University College 
London from 9 - 13 August 1971. Eighty delegates attended 
from twentyfive countries, and the Commission Board were 
honoured to welcome, among the delegates, four Council 
Members of ISP, the President, the Secretary General, 
the Treasurer and the Congress Director (of the XIIth 
Congress to be held in Ottawa in 1972). 
During seven technical sessions the papers reproduced 
in these proceedings were each presented by the author 
and discussed. Verbal presentations and discussions 
also took place for some lines of study where papers had 
not been produced. The Commission Board wish to thank 
the authors for their valuable contributions, and all 
participants for the interesting discussions which ensued. 
The Commission Board also wish to acknowledge most 
gratefully the assistance received from the following: 
the Provost of University College London for the use of 
College premises for technical meetings and also for 
the Symposium Dinner attended by 66 delegates and their 
ladies on Thursday 12 August 1971; 
the President of the Photogrammetric Society who 
entertained delegates and ladies at a Reception on 
Monday 9 August 1971; | 
the President of the Royal Institution of Chartered 
Surveyors for allowing the Institution premises to be 
used for the Reception; 
and lastly the Director General of the Ordnance Survey 
who provided accommodation for one technical session 
on Wednesday 11 August 1971, and then permitted 
delegates to visit areas of work in the new Ordnance 
Survey Headquarters building at Southampton.