1. The Shape of Animations Jason Harrison (Fiddling with the algorithms of Jeffery Boyd and Jim Little, and the animations of Jessica Hodgins, James O’Brien and Jack Tumblin)

2. Animation Metrics l “rate” animations by using metrics l use comparisons for databases, analysis, description... l aim for metrics based on human perceptual processes l Start with “Shape of Motion”

3. Shape of Motion l Jeffery Boyd and Jim Little l analysing video without models l optical flow l time varying signals l relative phases of signals l feature vector

4. N+1 frames... optical flow time-varying scalars scalar sequences phases {s 11, s 12,…, s 1n }{s 12, s 22,…, s 2m }{s n1, s n2,…, s nm } 11 22 mm... (phase reference) (s 1, s 2, …, s m ) feature vector(F 1, F 2, …, F m-1 ) phase features F 1 =  1 -  m F 2 =  2 -  m F m-1 =  m-1 -  m... “Shape of Motion”: Data Flow

5. Scalars computed l x coordinate of centroid l x coordinate of centroid weighted by |(u,v)| l y coordinate of centroid weighted by |(u,v)| l weighted centroid x - unweighted centroid x l weighted centroid y - unweighted centroid y l aspect ratio l aspect ratio weighted by |(u,v)| l aspect - weighted aspect l x coordinate of centroid weighted by |u| l y coordinate of centroid weighted by |u| l x coordinate of centroid weighted by |v| l y coordinate of centroid weighted by |v|

6. Boyd and Little’s Experiment l 6 participants l Walk for about 15 minutes l Toss first 2 passes l Analyse 7 passes l Compare between participants (control variable)

7. Example Gait (total sequence is 76 frames long)

8. Results aspect ratio x coordinate of centroid

9. Human Perceptions and Judgements of Motions l Jessica Hodgins, James O'Brien, and Jack Tumblin at Georgia Tech l participant study l dynamics model used to simulate runner l wireframe and polygonal models l camera moves steadily with runner

10. Animations: l 72 4-second running animations (36 of each model) l shoulder swing l motion computed dynamically l currently lost on /imager/raid

11. “Shape of Animations”: Data Flow l remove moving floor (chroma key) l crop and scale down by half l convert to grey scale l compute optical flow l compute fundamental frequency l pick good reference signal for phase l compute feature vectors

12. Fundamental Frequency l Median frequency of sequences for an animation l (min/max/ave/median) Stick figure animation

13. Any patterns? phase

14. One pattern x coordinate of centroid aspect ratio

15. Future Work l order sequences based on features? l clustering, rankings? l automatic analysis? l polygonal versus stick models?

16. Effect of Rendering Models? l geometry and surface appearances l lighting l camera position, parameters and movement l should resolution and frame rate be an issue?