Photogrammetric prediction of girdle pressure

A new method is proposed for indirect prediction of skin pressure induced by a tight-fit girdle, using in situ photogrammetric measurements in a close range. The 3D information of the markings on girdles being worn by seven woman subjects was acquired by five photographs captured from different horizontal angles. After digitizing the markings on the photographs, the body curvature and fabric strain at eight specific positions were calculated. From the result of the ANOVA test with repeated measures, both the body curvature and fabric strain were significantly different among subjects. Based on the materials' force-strain curves obtained from the Instron tensile test, the corresponding girdle pressure P was predictable by the local strain ε, fabric tension per unit length T and body curvature K. The predicted pressure values were verified by experimental measurements using novel pliance-x pressure sensors. The root-mean-squared error was 3.57 mmHg while an error of 4 mmHg was inherent in the current pressure measuring system. The correlation coefficients r (0.935) and r² (0.873) indicated a significant linear relationship between the predicted and experimental pressure values (p < 0.001).