Calibration of the Olympus UZ-500
The goal of our scanning project is to build a 3D scanning system with two digital cameras and one
PMD camera. But these cameras all have a distortion, which would make the matching of the
pictures very hard. So one of the main tasks of our project is the calibration of our cameras, so we
could deskew them.
Two important methods exist, which could be used for calculation of the intrinsic parameters: The
Tsai algorithm and the Zhang algorithm. Tsai's algorithm needs pictures of a test field and exact
data about position and movement of camera and test field. The algorithm of Zhang is more
complex and needs more computing power. But for calculation with the Zhang algorithm are only
pictures of the test field needed, without any position data. So we chose Zhangs calibration method,
because it is easier to handle and computing power is no problem with modern systems.
We will now look how the Olympus UZ-500 was calibrated. We took many pictures, cam checker
calculated the intrinsic parameters and then we deskew some pictures. Now we introduce step by
step, what is important, when a camera should be calibrated.
2.1. The experimental setup
We used the Olympus camera, one laptop and a black/white chessboard for the setup. The
chessboard was fixed on the wall and the camera stood on its tripod in front of the chessboard.
(the experimental setup)
For every zoom and focus setting we made ten pictures from different views. The camera was
slightly moved after taking a picture. With our automated capturing tool, which is presented in the
tool documentation by Sebastian Szczepanski, we could take pictures for one zoom and all 120