Practical estimation of DPIV uncertainty using pseudo-image pairs

While the sources of uncertainty in PIV measurement have long been understood, quantifying the contribution of each source has proved elusive. Here we present a straightforward approach using image pairs formed from a real image and that same image, subject to a uniform non-integer displacement. This procedure thus naturally incorporates contributions of image quality, optical setup, and pixel resolution to uncertainty. The pseudo-image pairs for a range of displacements are used to estimate an ensemble of displacement vectors, which is then used to estimate the bias and random errors in displacement. This method is particularly useful for identifying pixel locking bias. Applications of this approach to both fully-developed turbulent pipe flow and impinging jet flow will be presented.