A networked and computer-controlled multi-sensor 3D fringe projection measurement system

• Main Author: Qudeisat, Mohammed Ahmed
• Published: Liverpool John Moores University 2012
• Subjects: 615.842
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589740

A 3D non-contact real-time multi sensor fringe measurement system is proposed in this research. The system is designed to help radiotherapists detect human body measurements and motions during the cancer radiotherapy treatment process in real-time. The ability to detect body movements will help radiotherapists to accurately estimate the actual radiation dose that was delivered to the tumour volume. The researchers at JMU built a three-sensor system that covers 3600 around the object so that the system can have full visibility around the human body under treatment. Each sensor consists of one camera and one projector and each sensor works on its own exclusive light bandwidth to enable all sensors to work concurrently without affecting each other's operation. Each sensor is connected to its own data processing unit that controls its operation and carries out data processing tasks and all three data processing units are connected to a main central computer that controls and coordinates the operation of the three sensors. The author developed a novel empirical calibration approach to calibrate the three sensors concurrently; the proposed calibration approach solves the depth calibration problem and the perspective problem to provide the system with the ability to measure 3D shapes in an absolute physical coordinate system that is consistent with the coordinate system of the radiotherapy treatment machine. The author also implemented two algorithms for absolute 3D body shape measurements. The first is a multi-frame algorithm using the phase-stepping technique while the second is a single-frame algorithm that is based on the Fourier Fringe Analysis technique. A performance comparison between these two methods is given in the literature. Finally, the author describes measurement validation and error reporting methods to provide the system with the ability to estimate the quality of its own measurements, to detect errors and report failures in the measurement process. This feature is very crucial to system operation especially in sensitive applications like cancer treatment as it provides qualitative and quantitative measures of validity to the measurements. This research has resulted in a practical real-time system that is implemented at both, the LAB and Christie Hospital Manchester. The system has been thoroughly tested and it has shown very good performance in terms of reliability, accuracy, usability and speed.