Saccade Mirror calibration

Summary

A high-speed gaze controller, Saccade Mirror, enables high-speed tracking (1msAuto Pan-Tilt technology) and can keep high-magnification imaging of dynamic target objects. This technology has various applications of 3D measurement of dynamic objects; efficient factory automation; precise computer graphics of flying birds or insects; and high-performance human-computer interaction. Although precise calibration is important for high-magnification 3D measurement by Saccade Mirror, conventional calibration methods are difficult to apply; shallow depth of field (DOF) due to long focal lengths at close focus position, and mechanical differences in a gaze model.

We propose a deepening DOF method with episcopic illumination and retroreflective calibration pattern, which provides sufficient luminance even with quite a small aperture (Fig. 1). The mirror-based gaze controller can introduce a coaxially placed projector with a beam splitter, which is almost the same system configuration as Dynamic Projection Mapping technology (Lumipen) in our laboratory. We can place the calibration pattern within the DOF even near the Saccade Mirror, and realize a wide gaze range calibration.

Moreover, we also propose a new gaze model with mirror thickness for Saccade Mirror, which has large translations of center of projection with two rotational mirrors (Fig. 2). Based on the calibration pattern captured at the wide gaze range by deepening DOF, we properly apply bundle adjustment procedure, which is a general camera calibration framework, and can achieve Saccade Mirror calibration.

Fig.1 System configuration to deepen DOF.		Fig.2 Mirror-based gaze model.

Reference

1. Tomohiro Sueishi, Hiromasa Oku and Masatoshi Ishikawa: Mirror-based High-speed Gaze Controller Calibration with Optics and Illumination Control, 2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) (Hamburg, 2015.9.30)/Proceedings, pp.3064-3070 (2015)
2. Kohei Okumura, Hiromasa Oku and Masatoshi Ishikawa: High-Speed Gaze Controller for Millisecond-order Pan/tilt Camera, 2011 IEEE International Conference on Robotics and Automation (ICRA 2011) (Shanghai, 2011.5.12) / Conference Proceedings, pp.6186-6191