ABSTRACT
Basing on laser triangulation principle and structured illumination, this dissertation designed a set of laser 3-D scanning system for foot, studied the key technology of this system, and successfully developed the prototype of foot laser scanning system. The main work includes:
After consulting relative references domestic and abroad, the principle of the scanning system based on laser triangulation principle is analyzed. Basing on the camera model, the mapping relationship between the surface profile points of foot and the corresponding pixel points of light band is deduced.
The general structure is designed which includes image capture system, synchronous motion system and mechanical structure. The debug and control program is completed which realized the synchronous running of the image capture system and motion system.
The calibration of foot laser scanning system is implemented, including the camera calibration and global calibration. A black-white chessboard calibration target and Zhang Zhengyou’s algorithm are adopted to calculate the intrinsic parameters of cameras. Basing on these, an accurate filament calibration target is designed to calculate the transformation matrix between world coordinates and pixel coordinates by DLT method so as to complete the global calibration of the foot laser scanning system.
After the installation and adjustment of scanning system, the scanning tests on the foot model and standard metal block were completed. Analysis on the section of point cloud shows that the relative measurement error in the length direction, height direction and depth direction is less than 0.6%. The technical indexes reach that: scanning range of 360mm×120mm×160mm(length×height×width), typical resolution of 1mm×0.2 mm×0.3mm(length×height×depth).
KEY WORDS:human foot scanning, laser scanning, global calibration, 3D digitalization