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Details of Grant 

EPSRC Reference: EP/C013506/1
Title: Application of Photogrammetry and Optical Scanning in Manufacturing
Principal Investigator: Ridgway, Professor K
Other Investigators:
Corney, Professor J Sims, Professor ND
Researcher Co-Investigators:
Dr R Gault Dr R Scott Dr A Sharman
Project Partners:
Department: Mechanical Engineering
Organisation: University of Sheffield
Scheme: Standard Research (Pre-FEC)
Starts: 01 October 2005 Ends: 31 March 2009 Value (£): 253,920
EPSRC Research Topic Classifications:
Design & Testing Technology
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
Panel History:  
Summary on Grant Application Form
The objective of the proposal is to introduce photogrammetry and optical scanning equipment to produce accurate three-dimensional models of the surface of an object. Although this is two items of equipment their use is linked and the full benefits of optical scanning cannot be achieved without using photogrammetry. Photogrammetry uses a very high-resolution digital camera to capture the image of a large object such as part of an aircraft or car. The image is enhanced by using small circular targets, which are attached to the object before the image is captured. These small circular targets provide a reference system on the object. In the case of a car or aircraft the targets are typically 600 mm apart and 8 mm diameter. In addition to the small circular targets coded targets comprising small uniquely shaped targets are also placed on the object at approximately 1 m intervals. The optical scanning system is used to capture the actual surface data of the object. The scanning system uses two cameras and a projector to project different fringe patterns on to the surface of the object. The fringe patterns are reflected at different angles dependent upon the distance and angle of the surface of the object. As the fringes patterns are reflected from the object the cameras use a system of triangulation, similar to finding the position when walking with a map and compass, to accurately calculate the position of any point of the surface of the object. In most cases the accurate positions of approximately1.3 million points are calculated. Unfortunately, to retain accuracy, the optical scanning system can only work over a small surface area and it is necessary to carry out a number of scans to collect data for a large object such as a car body. This is where the uniquely shaped targets identified by the photogrammetry system are used. The computer collecting all the point data uses the unique target shapes to stitch all the scanned shapes together and thus produce a digital model of the complete object. The alternative method of doing this would be to measure the object with a small probe continually passing up and down the object. This method is very slow compared to the use of photogrammetry and digital scanningThe method of accurately calculating the position of any point on the surface of an object can be very useful in a number of areas of manufacturing. A very basic case would be to accurately and quickly measure or produce a three-dimensional model of an object. This can be useful when examining worn parts where the amount of wear can be calculated by comparing models before and after use. This can be extended to the point where a system can be used to calculate the amount of material that needs to be added to a worn part to enable it to be remachined ready for reuse. A similar principle can be used to calculate the amount of wear occurring on cutting tools during machining. The system can also be used to compare the shape of an object after manufacture with the desired shape to calculate the amount of deformation produced. The system can also be used to design medical implants. When someone has a deformed jaw, or even if the jaw has been badly damaged in an accident, the dental surgeon can produce a wax model of an implant or replacement. The wax model can then be scanned using the optical scanning system to produce a three dimensional model. This can then be used to machine a replacement jaw or implant. Other research projects concern the collection of surface data from prototype products and components to design production tooling for a wide variety of manufacturing processes. In all these cases equations need to be determined and built into models to predict the amount of distortion during the manufacturing process and thus design production tooling.
Key Findings
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Potential use in non-academic contexts
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Date Materialised
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Further Information:  
Organisation Website: http://www.shef.ac.uk