Research Output
Three step fringe projection for breast height profile imaging through phase shift variation
Digital fringe projection for hand surface coordinate variation analysis caused by osteoarthritis
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Publication
Breast imaging is essential in the study of breast cancer diagnose as well as monitoring of breast cancer patients. Preliminary early detection of breast tumors may aid in the survival rates of cancer patients thus preventing the cancer from metastasizing to other body parts or organs. The current trend of breast imaging involves the usage of mammograms, breast ultrasound and MRI which may be harmful due its hazardous imaging sources. Therefore, an imaging method for identifying the breast surface changes using non-hazardous imaging sources based on the three-step fringe projection method is developed. In this work, a digital fringe projection system with three phase shift variances was developed to perform imaging of a round shaped phantom breast. The setup for fringe projection system consists of a digital projector, a computer and a camera. The value of phase shift increment that was experimented are π/4, π/2 and 2π/3. The phase shift was varied to determine the appropriate phase shift on the round shaped breast based on the three-step fringe projection. The fringe visibility calibration of the three step fringe projection system based on the camera aperture settings of f/5.6 is calibrated to enhance the fringe pattern contrast during breast height profiling. Phase Mapping and Phase Unwrapping technique was applied to obtain the height profile of the round breast and was compared to measurements obtained from a digital vernier caliper. The results demonstrate that the 2π/3 had the most optimum height profile image with a standard eviation of less than 0.08 cm from the digital caliper measurements. Based on the results, the 2π/3 phase shift is most suited to be applied in the imaging of round breast when applying the three-step fringe projection.
Publication
Hand osteoarthritis is one of the most common forms of arthritis which impact millions of people worldwide. The disabling problem occurs when the protective cartilage on the boundaries of bones wear off over time. Currently, in order to identify hand osteoarthritis, special instruments namely X-ray scanning and MRI are used for the detection but it also has its limitations such as radiation exposure and can be quite costly. In this work, an optical metrology system based on digital fringe projection which comprises of an LCD projector, CCD camera and a personal computer has been developed to anticipate abnormal growth or deformation on the joints of the hand which are common symptoms of osteoarthritis. The main concept of this optical metrology system is to apply structured light as imaging source for surface change detection. The imaging source utilizes fringe patterns generated by C++ programming and is shifted by 3 phase shifts based on the 3 steps 2 shifts method. Phase wrapping technique and analysis were applied in order to detect the deformation of live subjects. The result has demonstrated a successful method of hand deformation detection based on the pixel tracking differences of a normal and deformed state.