Two-dimensional simulations of displacement accumulation incorporating shear strain

Accumulating a sequence of incremental displacement estimates is a common technique in ultrasonic motion tracking, but the statistical relationships between these incremental estimates are not well understood. Using simple 2D simulations of a scattering medium under normal and axial shear strain, it is shown that the covariance between estimation steps has significant effects on the final accumulated estimate. Displacement estimation errors induced by strain are positively correlated, while errors induced by electronic noise are negatively correlated. Normal and axial shear strain share these statistical properties but differ in their dependency on tracking kernel size.