Tilted angle measurement method of modular unit by 3d reconstruction of image

This paper reviews a method of measuring the tilted of horizontal angle of modular unit roof that occurs during fabrication and site assembly phase using three-dimensional restoration image process. Checkerboard patterns were used for camera calibration, and image analysis performed 3D reconstruction by locating the center coordinates of the circular target. A miniature model experiment was conducted before it was applied to the actual modular unit. The experiment measured the target at a distance of 300mm, 400mm, 500mm for the eight tilted angles of 0.5°, 1°, 1.5°, 2°, 3°, 5°, 7° and 10°, depending on the quantity (4,8,16,32,64,128 sheets) and distribution of concentration and distribution of the image data used for camera calibration. In sections with a tilted angle of 4 degrees or less, the error of the measurement angle using the concentrated image data was less than the error of the measurement angle using the dispersed image data. The result of the target at a distance of 400 mm, 500 mm, excluding 300 mm, showed a small error at a tilted angle of less than 3 degrees. The result of 300mm distance showed very large errors due to distortion of circular targets. Errors were reduced by the number of images for camera calibration, and the quantity of image data used for camera calibration from 32 sheets did not significantly affect the error.