Initial Estimates in Digital-image Correlation Method by a New Displacement Mode
非常应变模式数字相关方法的初值估计

On the basis of a new displacement mode for Digital image Correlation Method, both the Jacobian Vector and the Hessian matrix of Newton Raphson iterative procedure are given. The initial estimates of displacement and displacement gradients for Newton Raphson iteration are studied. Two methods of initial estimates are proposed: (1) using real time image subtraction scheme and a micro motion compensation mechanism to take zero constantly as initial estimates; (2) using fast iteration to give the initial estimates of displacement. Some problems in the initial estimates and the convergence of Newton Raphson iteration are discussed.