Fig. 1. Experimental apparatus for recording antennal movements. An animal was tethered on a free-moving Styrofoam ball to allow its unrestrained locomotion (Okada and Toh, 2000). Three video cameras were set just in front (1), top (2) and side (3) of the animal. Video images were processed by a 4-split multi-viewer, videotaped, and analyzed using a PC. Photograph on the right is an example of synthesized video frame after the processing, showing frontal (1), top (2) and side (3) views.