Precise optical method for three dimensional ship deformations measurement

We present an optical method to measure three dimensional (3D) ship deformations. This method is based on optical collimation theory and thereby, with a crosshairs image projected and captured in a collimation optical path, the 3D deformation angles, including the pitching angle, the yawing angle and the rolling angle, could be calculated by image’ variation. In order to improve the measurement precision, sub-pixel location algorithm is adopted in image processing. Particularly, given that the rolling angle is the most difficult to measure in a collimation optical path, numerical simulation is carried out to analysis the error characteristics of this angular measurement. Experimental results indicate that this 3D ship deformations measurement achieve the precision of several arcsecs in the distance of 25m and in the deformation range of -120″~120″.