Zicheng Liu and Michael F. Cohen. Keyframe motion optimization by relaxing speed and timing. In Computer Animation and Simulation '95 -- Proceedings of the 6th Eurographics Workshop on Simulation and Animation, pages 144--153, Springer Verlag. Maastricht, Netherlands, 1995.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... degrees of freedom to control the balance as with the torso orientation in [22] or with the ankles, hip, and waist in [14] Systems based on Dynamics have demonstrated the possibility to achieve a dynamic balance for the motion of various legged entities [14] 25] 26] Optimal control [12] [19], 27] can generate realistic physically based postures and animations. Nevertheless, it usually faces high computation cost for large dimension systems (i.e. more than 50) and lacks the design freedom required for the animator. Furthermore, as stated in [14] 26] the associated parameter ....

....and lacks the design freedom required for the animator. Furthermore, as stated in [14] 26] the associated parameter space of both Dynamics and Optimal control is not easy to handle for an animation designer. The performance and the interface have been improved with a keyframe based optimization [19]. However, the design problem of complex key postures with balance remains. The position control of the center of mass has found considerable attention in the control of legged robots (and animals) 6] 11] 13] 25] 26] However, the position of the center of mass is only controlled ....

Z. Liu and M.F. Cohen, "Keyframe Motion Optimization by Relaxing Speed and Timing," Proc. Sixth EUROGRAPHICS Workshop Animation and Simulation, Maastricht, Springer Verlag Wien, Sept. 1995

....design from the storyboard and artistic directives about the characters. The logical requirement on the software tools is to ask both for the highest realism and the greatest freedom of design in order to edit and improve any detail of the motion. However, as appears on Figure 1 (inspired by [6]) the techniques providing highly realistic motions, at least from the physical aspect of the problem, are the ones providing the least design freedom. We now review them and analyze why the live recording, also known as Performance Animation, is now the most popular technique is that field. ....

....optimization techniques [10] 11] they still face severe computation costs for such high dimension of animation space. As appears on Figure 1, the second limitation of that technique comes from the insufficient amount of animator control over the resulting motion. A recent advance in that field [6] improves these two aspects by combining the optimization with the keyframe technique: the animator has a greater control by specifying keyframed postures, eventually with their associated key time, as constraints. It is also possible to specify higher level constraints as velocity of the ....

Liu Z., Cohen M.F., Keyframe Motion Optimization by Relaxing Speed and Timing, Proc. of 6th EUROGRAPHICS Workshop on Animation and Simulation, September 95, Maastricht, Springer Verlag Wien

....on the error as measured by the Euler Lagrange error functional. Other differences include the use of variable frames (the system inserts these) and unconstrained minimization. In optimizing over a small number of variables for fast algorithms, our work is also similar to that of Liu and Cohen [12]. Although this paper describes the creation of quaternion splines primarily for animation, splining in curved spaces and constructing minimal energy motions is important to other communities such as computer aided geometric design, robotics and kinematics. A few related papers are found in [8, ....

Z. LIU and M.F. COHEN. Keyframe motion optimization by relaxing speed and timing. In 6 th Eurographics Workshop on Animation and Simulation (Maastricht 1995), pages 144--153, 1995.

....our approach is similar to the spacetime constraints paradigm ( witkin kass 88] cohen 92] liu et al. 94] in that we seek to minimize an objective function, our approach is more closely allied to traditional keyframing and our primary application is to interpolation of keyframes. Unlike [Liu Cohen 95] we fix the keyframes both spatially and temporally as is more common in conventional animation techniques (except that we allow partial keyframes that fix only some degrees of freedom) In addition, we improve on the method presented in [Liu Cohen 95] in that we optimize the intermediate path ....

....is to interpolation of keyframes. Unlike [Liu Cohen 95] we fix the keyframes both spatially and temporally as is more common in conventional animation techniques (except that we allow partial keyframes that fix only some degrees of freedom) In addition, we improve on the method presented in [Liu Cohen 95] in that we optimize the intermediate path between keyframes instead of using a simple spline or hermite approximation. In our approach, specification of generalized co ordinate velocities is not necessary since our optimization procedure requires only the position of keyframes. There has been ....

Zicheng Liu and Michael F. Cohen. "Keyframe Motion Optimization By Relaxing Speed and Timing", 6th Eurographics Workshop on Animation and Simulation.

....5] although these techniques are not shown to be generalizable to quadrupeds. The concept of trajectory optimization for animation can best be traced back to the spacetime constraints work of Witkin and Kass[18] This area has subsequently been explored in greater depth by Cohen[6] Liu and Cohen[11], Rose et al. 13] and others. Our work focusses on how to make a trajectory optimization approach practical for the problem of quadruped animation. Trajectory optimization is a general way of framing motion synthesis problems, but there are a great number of choices that need to be made in order ....

Z. Liu and M. F. Cohen. Keyframe motion optimization by relaxing speed and timing. Computer Animation and Simulation '95, Proceedings of the Eurographics Workshop, pages 144-- 153, 1995.

....on the error as measured by the Euler Lagrange error functional. Other differences include the use of variable frames (the system inserts these) and unconstrained minimization. In optimizing over a small number of variables for fast algorithms, our work is also similar to that of Liu and Cohen [12]. Although this paper describes the creation of quaternion splines primarily for animation, splining in curved spaces and constructing minimal energy motions is important to other communities such as computer aided geometric design, robotics and kinematics. A few related papers are found in [8, ....

Z. LIU and M.F. COHEN. Keyframe motion optimization by relaxing speed and timing. In 6 th Eurographics Workshop on Animation and Simulation (Maastricht 1995), pages 144--153, 1995.

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Zicheng Liu and Michael F. Cohen. Keyframe motion optimization by relaxing speed and timing. In Computer Animation and Simulation '95 -- Proceedings of the 6th Eurographics Workshop on Simulation and Animation, pages 144--153, Springer Verlag. Maastricht, Netherlands, 1995.

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Z. Liu and M. F. Cohen. Keyframe motion optimization by relaxing speed and timing. In

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