The shape function and lens distortion affect the accuracy of digital image correlation (DIC). Many studies have been conducted on the shape function and lens distortion correction, and an appropriate shape function with lens distortion correction can reduce measurement errors. However, the influence of the implementation order of correcting lens distortion with known distortion parameters and matching subsets with different shape functions has not been discussed. The two implementation orders are: correcting matched grid points after matching distorted subsets and correcting distorted images before matching the subsets. The former will cause undermatching, and the latter will produce additional interpolation errors. Simulations and an experiment with known lens distortion parameters were performed to evaluate the accuracy of the two implementation orders. The forward additive Gauss–Newton algorithm with first-order and second-order shape functions was applied to the measurements. The results show that the order of correcting distorted images before matching subsets has higher accuracy as compared with another order, and a second-order shape function should always be used unless the underlying deformation is known to be lower order.
The illumination variation exerts a significant influence on the accuracy and efficiency of digital image correlation (DIC) technology. However, the existing intensity change models assume that all the pixels in the reference subset have the same gray-level intensity change parameters, which cannot accurately reflect the effect of illumination variations. We pay attention to the position effect on intensity variations and propose a position-based intensity change model to study the illumination variation in DIC. The proposed model combines the gray-level intensities, the illumination variation, and the position parameters of a reference subset. The forward additive Gauss–Newton algorithm with a first-order shape function is applied to evaluate the feasibility and effectiveness. Simulation and experimental results verify that the proposed model has higher accuracy in different illumination conditions as compared with the existing second-order intensity change model.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.