IMPROVED 3-DIMENSIONAL IMAGE CORRELATION FOR SURFACE DISPLACEMENT MEASUREMENT

A PC-based, 3-D surface profile and displacement measurement system ca pable of micron-level accuracy using moderately priced off-the-shelf e quipment has been developed. For use in field applications, a simplifi ed calibration process using precision grids and camera translations i s developed. An improved image correlation process is developed which corrects for perspective distortions due to viewpoint differences betw een the two cameras. The accuracy of the system was assessed experimen tally and results expressed using several different error measures, in cluding a new error measure proposed by the authors. The accuracy for both the profile and displacement measurement systems was established through a series of profile and translation tests. The baseline tests confirmed that the measurement system is capable of highly accurate fu ll-field measurements. The system was also used successfully to measur e both the bending of a clamped circular plate under pressure loading and the local buckling which occurs during tension loading of a cracke d plate. (C) 1996 Society of Photo-Optical Instrumentation Engineers.