Stereo Matching and 3D Reconstruction via an Omnidirectional Stereo Sensor

A catadioptric vision system using diverse mirrors has been a popular means to get panoramic images(K.Nayar, 1997) which contains a full horizontal field of view (FOV). This wide view is ideal for three-dimensional vision tasks such as motion estimation, localization, obstacle detection and mobile robots navigation. Omnidirectional stereo is a suitable sensing method for such tasks because it can acquire images and ranges of surrounding areas simultaneously. For omnidiretional stereo vision, an obvious method is to use two (or more) cameras instead of each conventional camera (K.Tan et al., 2004; J.Gluckman et al., 1998; H.Koyasu et al. 2002; A.Jagmohan et al. 2004). Such two-camera (or more-camera) stereo systems are relatively costly and complicated compared to single camera stereo systems. Omnidirectional stereo based on a double-lobed mirror and a single camera was developed (M.F.D. Southwell et al. 1996; T.L. Conroy & J.B. Moore, 1999; E. L. L. Cabral, et al. 2004; Sooyeong Yi & Narendra Ahuja, 1996) . A double lobed mirror is a coaxial mirror pair, where the centers of both mirrors are collinear with the camera axis, and the mirrors have a profile radially symmetric around this axis. This arrangement has the advantage to produce two panoramic views of the scene in a single image. But the disadvantage of this method is the relatively small baseline it provides. Since the two mirrors are so close together, the effective baseline for stereo calculation is quite small. We have developed a novel omnidirectional stereo vision optical device (OSVOD) based on a common perspective camera coupled with two hyperbolic mirrors, which are separately fixed inside a glass cylinder. As the separation between the two mirrors provides much enlarged baseline, in our system, the baseline length is about 200mm, the precision has improved correspondingly (Fig. 1).