  Reconstruction and monitoring of displacement and strain fields is an
important problem in engineering. We analyze the remote and non-obtrusive
methods of strain measurement based on photogrammetry and Digital Image
Correlation (DIC). The method is based on covering the photographed surface
with a pattern of speckles and comparing the images taken before and after the
deformation. In this study, a comprehensive literature review and comparative
analysis of photogrammetric solutions is presented. The analysis is based on a
specially developed Digital Image Synthesizer To Reconstruct Strain in Solids
(DISTRESS) Simulator to generate synthetic images of displacement and stress
fields in order to investigate the intrinsic accuracy of the existing variants
of DIC. We investigated the Basic DIC and a commercial software VIC 2D, both
based on displacement field reconstruction with post processing strain
determination based on numerical differentiation. We also investigated what we
call the Extended DIC where the strain field is determined independently of the
displacement field. While the Basic DIC and VIC 2D are faster, the Extended DIC
delivers the best accuracy of strain reconstruction. The speckle pattern is
found to be playing a critical role in achieving high accuracy for DIC.
Increase in subset size for DIC does not significantly improves the accuracy,
while the smallest subset size depends on the speckle pattern and speckle size.
Increase in the overall image size provides more details but does not play
significant role in improving the accuracy, while significantly increasing the
computation cost.
