Visualizing the motion of the pectoral fins is important for enhancing
the authentic quality of the artificial fish model. A pair of
motionless pectoral fins can make an otherwise life-like swimming fish
look awkward. From the simplified functional modeling of the pectoral
fins described in Section 
, a straightforward
visualization will be to make the geometric model of the pectoral fins
be at an angle corresponding to the 
's. Since will
only change when necessary and successive angles are
generally not continuous, the fin motion will unfortunately look
sudden, stiff and hence unrealistic. If we interpolate the angles to
yield smooth motion, the fins will look almost motionless compared to
the fish's lively body movement. For this reason, we separate the
control for visualization purpose from the control for fish locomotion
(or functional purpose) described in Chapter .
Real fish can move their pectoral fins in extremely subtle and complex
ways that may not be possible to capture accurately using our
simplified model. However, many of these delicate details of the fin
motions are barely detectable from any distance. In fact, the
pectoral fins often move so quickly that only a rough motion pattern,
such as flapping or oaring, is distinguishable. We have simulated
these two main motion patterns of pectoral movement in the artificial
fishes. The implementation details can be found in
Appendix and the results are depicted in
Fig. and Fig. below.
Figure: Snapshots of the pectoral flapping motion.
| Xiaoyuan Tu | January 1996 |
