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A REAL TIME PHOTOGRAMMETRY SYSTEM FOR UNDERWATER AND 
INDUSTRIAL APPLICATIONS 
John Turner (Managing Director), David Yule (Photogrammetrist) and Joe Zanre (Electronics Development Engineer) 
Camera Alive Limited, Aberdeen, Scotland 
ISPRS Commission V 
ABSTRACT: 
A market survey within the Offshore Oil and Gas Industry highlighted the operational deficiencies in providing a dimensional 
measurement service based on traditional photographic based photogrammetry. This has led to the development of a real- time 
photogrammetry system which can be used operationally in air or underwater. 
The developed Non-Contact Measurement System (NCMS) is used by engineers and operational technicians to extract three- 
dimensional data for use in on-site decision making processes, or for reporting via CAD systems, to aid with construction, 
maintenance and repair. 
The system allows a range of inputs, including a purpose designed digital stills camera incorporating a high resolution CCD, 
video cameras, scanned photographs and satellite images. Analysis is carried out using a PC based image processing system, 
with full stereo viewing, and software written as a Microsoft Windows application. 
The paper introduces the development of the system, reports on its benefits and introduces the applications for such a product. 
KEY WORDS: 
Real-Time, Digital Photogrammetry, Digital Camera, Image Processing, Close-Range, CAD/CAM, Underwater. 
1. INTRODUCTION 
1.1 Historical 
Camera Alive have used conventional photogrammetry as the basis for a 
measurement service provided to the Offshore Oil and Gas Industry since 
1980. Its applications have been focussed on underwater activities where 
remote measurement of three- dimensional objects was necessary for such 
tasks as the repair or maintenance of steel tubulars, the monitoring of corrosion 
and the evaluation of weld defects or impact damage. Other applications, out 
of the water, have included the measurement of drilling derricks, the survey 
of structural components of the offshore platforms between the sea and the 
deck, measurements required to plan the installation of additional pipework 
and to fabricate clamps or other strengthening or repair pieces. ~~ Figure 1 
illustrates a typical result from the underwater survey of tubular steel structural 
members prior to the installation of a clamp. 
Since the introduction of the service in the North Sea in 1980 photogrammetry 
has been used in almost every offshore producing region of the world. 
Marketing and sales activity had defined the main three- dimensional meas- 
urement requirements of the Offshore Industry as: 
* Fast Image Capture and Presentation of Results; 
* Accuracy; 
* Objectivity; 
* Cost Effectiveness. 
While conventional photogrammetry, based on the use of photographic camer- 
as, was regarded as a useful tool for many applications, its use was being 
excluded from many potential applications because: 
It was not able to deliver the measurements without a significant delay. 
Photographs had to be chemically processed to confirm that they contained 
the subject matter and were of good photographic quality. The photographs 
then had to be transported onshore for analysis. A further delay resulted in 
ascertaining the precise measurements required from the analysis, in liaison 
with the engineer. The result then had to be presented in draft form before 
being revised and finally presented. Often the results were not available in 
time to be beneficial within an ongoing operation. This restricted the use of 
photogrammetry to surveys which could be carried out in advance of the 
remedial or installation phase of the job. 
The extraction of the data was not able to be controlled directly by the user of 
the data, which led to interpretation errors. 
The cost of the service could only be justified when no other technique could 
be used to obtain the measurements, hence restricting the range of applications. 
In 1989, at the instigation of five far sighted Oil and Gas Companies, a detailed 
analysis of their measurement requirements was made. This highlighted in 
particular the programmed exploration and production in water depths of 
greater than 300 metres. At these water depths the use of divers became 
prohibitively expensive and potentially damaging to their health. The alter- 
native was an increase in the use and expansion in the range of applications of 
Remotely Operated Vehicles (ROVs), figure 2. If this was to be achieved it 
would be necessary to have available a remote dimensional measurement 
system that could meet the need for cost effective, accurate and objective 
dimensional data within short time scales, preferably in real time. The objec- 
tives for the development had been set. 
1.2 Feasibility 
A range of state of the art technological solutions to remote dimensional 
measurement problems were considered. These included laser and acoustic 
techniques. However, the requirement for any system to be integrated into an 
ROV which was always moving relative to the subject focussed the investiga- 
tion on techniques that could acquire data on the whole subject instantaneous- 
ly, rather than sequentially. For this reason a visual imaging technique was 
essential. 
1.3 Development Objectives 
The feasibility study concluded that, on the basis of the main requirements for 
speed, accuracy, objectivity and cost effectiveness, the development objec- 
tives should be set as follows: 
The use of photogrammetry principles would meet the requirements of accu- 
racy and objectivity, as well as that of using a visual imaging technique that 
would capture the whole scene instantaneously. 
The speed of image capture requirement necessitated replacing the photo- 
graphic cameras with electronic imaging devices, with a corresponding change 
in the analysis equipment to handle these electronic images. 
The duration of the measurement process could be reduced by automating 
many of the set-up and measurement routines. The use of analysis equipment 
designed to handle electronic images would enable this process. 
The cost benefit would be achieved by replacing the expensive optical / 
mechanical analysis system with a PC based image processing system, as well 
as designing the user interface so that it could be operated directly by the 
engineer who required the information, rather than by a skilled technician.