The calibration tool Calib Tool supports calibration of a stereo vision system. The tool comprises a calibration grid matcher, a number of calibration techniques and calibration monitoring facilities. In this software image plane errors are minimised iteratively and robustly from an initial estimate of the calibration (Tina memo 2000-009). The technique permits the selection of arbitrary parameters a-priori and can also deal with radial distortion effects. The methods also permit the estimation of calibration parameter covariances for the purposes of optimal combination. The same software can also be used for the more standard tile based calibration techniques, such as Tsai.
Parameter dialog boxes are provided for altering a number of algorithmic parameters. Calibration is carried out with a local version of the camera model which can be copied from and back to the global model used in the stereo vision modules within Tina.
The left and right cameras of a stereo system can now be calibrated using the wire-frame models (Tina memo 2006-007). These models have been extended to encode occluding boundaries (lines between conic cross-sections) and lateral feature shifting. Lateral shifting is important in order to obtain good alignments to features in curved objects lit by arbitrary illumination. Good alignment is essential for statistical testing of feature visibility.
The recommended strategy for wire frame model constrution is a s follows;
Automatic alignment by the model matcher will be progressively supported as more views are added. More information is available in the calibration demonstration directory.