New initiatives in phase unwrapping in digital photoelasticity

Phasemaps obtained by phase-shifting techniques contain ambiguous zones. To obtain total fringe order by phase unwrapping, the phasemap should be corrected for ambiguity. Each available ambiguity removal method can resolve ambiguity for only a class of problems. Appropriate selection of these algorithms and their combination for a specific case can give a better result. A comprehensive ambiguity removal methodology is demonstrated in this paper. Disturbance in the intensity pattern of the phase shifted images due to lines and marks on the models lead to noise in phasemaps. This in turn affects the ambiguity removal and unwrapping procedures. A methodology has also been proposed to remove the lines and marks from the phase-shifted images.