Photogrammetric Modelling for 3D Reconstruction from a Dual Fluoroscopic Imaging System
Date
2019-01-03
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Abstract
Biplanar videoradiography (BPVR), or clinically referred to as dual fluoroscopy (DF), imaging systems are increasingly being used to study the in-vivo skeletal biomechanics of human and animal locomotion. DF imaging provides a novel solution to quantify the six-degree-of-freedom (6DOF) skeletal kinematics of humans and animals with high accuracy and temporal resolution. Using low-dose X-ray radiation, DF systems provide accurate bone rotation and translation measurements. In this research domain, a DF system comprises two X-ray sources, two image intensifiers and two high-speed video cameras. The combination of these elements allows for the stereoscopic imaging of the bones of a joint at high temporal resolution (e.g., 120-250 Hz), from which bone kinematics can be estimated. The utilization of X-ray-based imaging results in challenges that are uncommon in optical photogrammetry. Unlike optical images, the inherent lack of colour information in DF images complicates fundamental tasks such as the derivation of image observations for the system calibration. Furthermore, the incorporation of an image-intensifier to produce DF images results in high distortion artifacts that are uncommon in optical photogrammetry. The use of image intensifiers also results in non-uniform intensity response in the DF images. Unlike optical images with well-established camera models, the systematic distortion behaviour in DF images is empirically modelled. The novelty in this research work is in providing a complete, scientific, straightforward and accurate photogrammetric framework for deriving 3D measurements from a DF imaging system. This research work provides means for automating the DF calibration procedure and introduces solutions for improving the methodology of 3D reconstruction from DF imaging. A thorough photogrammetric analysis over the system aspects points out the weaknesses in the iii traditional 3D reconstruction procedures and suggests accurate alternatives. The dissertation presents five scientific contributions: (1) a semi-automated methodology to derive the image observations from time series DF calibration images, (2) validation of an empirical DF sensor model (bundle adjustment-based) for the calibration of the DF system and introducing it as a superior replacement for the traditional direct linear transformation-based (DLT) calibration approaches, (3) a rigorous accuracy assessment methodology for the evaluation of the DF system reconstruction capabilities, (4) a novel methodology for the temporal stability analysis of an imaging system calibration parameters, and (5) a virtual-3D-model means to facilitate establishing the alignment between stereoscopic DF image pair and an MRI/CT model (2D-to3D registration).
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Keywords
dual fluoroscopy, photogrammetric calibration, 2D to 3D registration, accuracy assessment, stability analysis, X-ray photogrammetry, biplanar videoradiography
Citation
Al-Durgham, K. M. (2019). Photogrammetric Modelling for 3D Reconstruction from a Dual Fluoroscopic Imaging System (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.