The most commonly used camera calibration method is perhaps the DLT (direct linear transformation) method originally reported by Abdel-Aziz and Karara (1971). The following pages are devoted to the DLT method:
The DLT method uses a set of control points whose object space/plane coordinates are already known. The control points are normally fixed to a rigid frame: calibration frame. The flexibility of the DLT-based calibration often depends on how easy it is to handle the calibration frame. The following pages provide some insight regarding the use of the calibration frame:
The main problem the DLT method has is that the parameters one obtains from the calibration are not mutually independent from each other. This jeopardizes the orthogonality of the rotation matrix. The following page introduces & explains an alternative approach reported by Hatze (1980).
In underwater motion analysis, light refraction at the water/glass/air interface causes deformation of the image. Fitting the deformed image to the object space/plane coordinates of the control points in turn causes deformed object space/plane. The following pages deal with the refraction error and the camera calibration issues in underwater motion analysis:
This section also includes pages dealing with some additional issues such as:
© Young-Hoo Kwon, 1998-