Dense 3D Displacement and Strain Measurement Framework of Miter Gates Using Computer Vision

Abstract

This paper investigates the framework of vision-based dense 3D displacement and strain measurement using a digital camera. The framework has three components: (i) Estimation of 3D displacement and strain from images before and after deformation (water-fill event), (ii) evaluation of the expected accuracy of the measurement, and (iii) selection of the measurement setting with the highest expected accuracy. The framework first estimates the full-field optical flow between the images before and after water-fill event, and project the flow to the finite element (FE) model to estimate the 3D displacement and strain. Then, the expected displacement/strain estimation accuracy is evaluated at each node/element of the FE model. Finally, methods and measurement settings with the highest expected accuracy are selected to achieve the best results from the field measurement. Physics-based graphics model (PBGM) is used effectively to simulate the vision-based measurements in a photo-realistic environment and evaluate the performance of different methods and measurement settings by comparing the estimated values with the ground-truth values. The framework investigated in this paper can be used to analyze and optimize the performance of the measurement with different camera placement and post-processing steps prior to the field test.