Texte intégral / Full text (pdf, 20 MiB) - Infoscience - EPFL

3.5. Gaze Behaviors to Enhance Character Realism
Motion
Capture
Walking cycles
Walking
+ Trajectory
Trajectories
Interest Point
Detection
Crowd
Engine
Motion Editing
Final
Animations
Figure 3.5: Overview of the offline architecture allowing the addition of gaze attention behaviors
to virtual characters.
3.5.1 Gaze Behaviors for Crowd Characters
As mentioned, our first model to add gaze attention behaviors to crowd characters is an
offline one. The overall outline of this architecture is depicted in Figure 3.5. We use the
character trajectories from an existing crowd simulation, created using a crowd simulation
engine developed in lab and described in [Maïm et al., 2009]. The trajectories simply consist
in the position and orientation of each character at each time step. We then combine these
trajectories with motion captured walking cycles in order to reconstruct the character walking
motions. We adapt these walking cycles in order to eliminate footskating effects due to the
changes in speed of the moving characters. Using the character and object trajectories, we
then automatically detect where each character should look and when by assigning a score to
each other character and object in the scene. This score is determined by a scoring function
composed of various subscores, each associated to a particular feature such as distance or
orientation. Finally, we adapt the character motions in order for them to perform the gaze
behaviors. We compute the displacement maps to be applied to each recruited joint in order
to perform the gaze motion. We then smoothly propagate these displacements over time in
order to obtain a natural movement. The complete character animations are then re-injected
into the crowd simulation engine in order to obtain the final results. This architecture and all
of its components are discussed in detail in Chapter 4.
43