Soil stability problems caused by vibratory loading, such as that of earthquakes and wind, have been increasingly observed. Designs and developments, which include a soil dynamic triaxial testing apparatus and a triaxial sample surface dynamic deformation measurement method based on the digital image processing technology, have been proposed to study the characteristics of soil under dynamic loads. The sub-pixel coordinates of corner points of squares on rubber membrane wrapping soil sample can be extracted using a high-speed camera that synchr...