Background
Photogrammetry is an attractive technology for dimensional control applications in shipyards, but, at a cost of $500,000+, traditional film-based legacy systems have discouraged most shipyards.  Since the middle 1990's digital camera systems have been available, but, here also, six-digit prices for software still make shipyard management shy away from using them.

Objectives
At the University of New Orleans, we are developing interface software that will tailor inexpensive topographic mapping software for shipyard production.  Successes with industrial collaborators already serve as instructional material for spreading the good news that digital image photogrammetry is a working option for easy, low-cost dimensional control.  Furthermore, a quality control feature can now be incorporated into the measurement process heretofore unrealized in shipyard applications, namely, the facility to compute the Geometric Dilution of Precision through photogrammetric error propagation analysis.

Application Potential and Uses

Modular Construction – As a commonly used technique for constructing large vessels, small units or modules are welded together for later fit-up to the vessel.  But distortions in welding necessitate that extra material be left on the mating edges to accommodate hand fitting.  So, to allow "neat fit" construction, digital image photogrammetry is an effective tool in dimensional control.  The system is quite portable, and component parts can be in motion during measurement.

Ship Repair – To expedite the repair of damage resulting from collision, digital image photogrammetry can perform very rapid and accurate as-built surveys.  Low cost systems will allow this technology to be used by smaller repair yards rather than being available only to large regional shipyards.  Some surveys can even be done while the vessel is in motion, as long as the damage is visible and accessible for targeting.

Stability Analysis – With digital image photogrammetry new power plants can be modified and retrofitted to old vessels without detailed plans of hull dimensions.  For instance, tugboat hulls can typically be surveyed with less than six hours of dry dock rental time, and naval architects can have the results by the next day.

Interference Design – Digital image photogrammetry offers a measure of convenience that converts to cost savings through the development of pipe fitting designs from as-built surveys of engine rooms and existing pipe racks.  To save time, technicians can travel to vessels in other parts of the world, quickly perform the requisite imaging (even while at sea), and return to the shipyard.  Specialized parts can then be fabricated and largely completed before the vessel arrives at the yard.

Development Partners/Principal Industry Collaborators

Avondale Shipyards

Bender Shipyards

Bollinger Shipyards

A. K. Suda, Inc., Naval Architects & Marine Engineers

Project Status Summary

Interface software for shipbuilding applications is in active development and testing at the University of New Orleans.  Field applications have been successful in all potential areas except for interference design, which is still under work.

Future Plans

Additional work is needed for integration with common computer assisted design  software packages that will also display Geometric Dilution of Precision results within the CAD application.
 

Fore more information contact:

Mr. Clifford J. Mugnier
Phone: (504) 280-7095
e-mail:  cjmce@uno.edu

GCRMTC TECHNICAL BRIEFS are published periodically by the Gulf Coast Region Maritime Technology Center, a U.S. Navy Center of Excellence in Advanced Marine Technology based at the University of New Orleans.  GCRMTC's Mission is to "enhance international competitiveness in the U.S. shipbuilding industry through sponsored research."   For additional information, contact:  GCRMTC, University of New Orleans, New Orleans, LA 70148, Tel: (504) 280-3871, Fax: (504) 280-3898, E-mail: jtsen@uno.edu

The contents of this publication reflect the views of the MERIC staff and are based on information obtained from the literature.  The contents do not necessarily reflect the official views or the policies of MERIC or the Gulf Coast Maritime Technology Center.  This publication does not constitute a standard, specification, or regulation.  MERIC does not endorse products, equipment or manufacturers.  Trademarks or manufacturer's names appear herein only because they are considered essential to the object of this publication.