This study introduces an efficient image-based three-dimension motion tracking system for civil structures. The proposed system consists of hardware (four camcorders, a commercial PC and frame grabber) and software. The effective software and measurement scheme are developed to obtain the dynamic motion with six degrees of freedom. Several laboratory tests were conducted to verify the effectiveness of the proposed system with the maximum error of less than 3%.

This study introduces an algorithm for geometric distortion corrections in sonar images. The proposed algorithm mainly consists of two stages. At the first stage, the raw images are processed with median filter and Frost filter for noise reduction and intensity enhancement. In the last stage, the geometric distortion correction is conducted using angular information given by a gyro sensor. The algorithm was successfully applied on raw sonar data collected on a pier survey.