Walking Cycle Animation and Interpolation. Rama Hoetzlein email@example.com. Recap… Where are we. 9:00-12:00 (morning) 13:00-16:40 (afternoon)
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Walking Cycle AnimationandInterpolation Rama Hoetzleinrama@create.aau.dk
Recap… Where are we 9:00-12:00 (morning) 13:00-16:40 (afternoon) DAILY TOPIC: Walking, Posing and AnimationKeyframes, Auto keyingQuick lab:Walk cycles Quick lab: Walk cyclesMuybridge, motion studies Posing Walk cycle dynamics, Human dynamics Keyframing Assignment: Animation MORNING: Animation AFTERNOON: Motion CaptureCritique of animations History and foundationsStart on Motion Capture topic Rotoscoping, camera tracking Current trends: Performace cap.Lab: Import of mo. cap dataAssignment: Refine animations. OR import mo.cap dataMotion Capture session with Stefania and Camilla Hagg- Full-body capture session Feb 21st (Mon) Mar 2nd (Wed) Mar 15th
Today.. 1. Key frame (drawing)2. Auto keysQuick lab: Walk cycle (#1) 3. Interpolation 4. Graph editorQuick lab: Walk cycle (#2)
Assistant Animators “Gradually we developed a professional class of ‘clean up men’ who took pride in their work. It was their skill that made the pictures look so fine, yet for a number of years they never got screen credit, nor even the salary they deserved…An ideal group would include an assistant animator (simple changes), second assistant (still learning), breakdown man, and inbetweener who could double as a handyman. The last category included everything: threading the film, taking a test over to the cutter..”
In computer animation, the software replaces the inbetweener with a mathematical process of interpolation.With interpolation, the computer automatically determinesintermediate frames from the start and end frames.* As a mathematical process, interpolation may not give the results you expect… But it is easy to get started..
Steps for Auto Keying Set total frames TurnAuto Key on Load theTiming panel here
Steps for Auto Keying Select object first.. Right-click on any attributeand select Set Key.Usually this is done onTranslate and Rotate of rig controllers.
Steps for Auto Keying Set time slider to desired time Notice lines tell you where you have keys. .. and move object to location for that time
Animating a Walk Cycle(first attempt) Use the Human rig provided. Or another if you like. 1. Use the Auto Key technique.2. Set your total animation time to 25 frames (8 sec)3. Hint: The time between strides is 1 second for full cycle (30 frames), ½ second per leg (15 frames)4. Note the body translates at a constant rate in space
Keyframingusing Interpolation Mathematical problem: Given a set of points, what are the most reasonable points in between?
Brief History of Computer Animationof Keyframes Linear interpolation…. just use a weighted average between points. Linear is discontinuous at the key points.Linear only account for two points.
Splines In boat building, splines are thin pieces of wood that are bent to fit the key points set by clamps.The spline interpolates the clamp points.
Bezier Curves Paul de Casteljau (1959), invented Bezier curves. Pierre Bezier used in automotive modeling. Key pointTangent point Bezier curves are continuous at the key points.Bezier curves interpolate the end key points (pass through them)
Bezier Curves Bezier curves require non-interpolated points 12 key points neededOnly 4 of these interpolate the curveIn practice the other 8 are made into tangent points. Polynomial Curves Use all the pointsto create a fit curve.Does not need to pass through the key points.Computationally expensive.
Why is this important in animation? Difference between this… and this…
linear “..simple linear animation between key frames will not produce a realistic result.” 1974, Burtnyk & Wein
Contact pose - Both legs are at their extreme point. Opposite arm is forward.Recoil - Weight falls on the recoil pose. Front foot fully touches. Body at lowest position, arms at extreme. Passing - Back leg passes the contact leg. Arms at sides.High point - Body at highest pose. Back leg is pushing body forward. Back toe peels off the ground. Contact – DOWN to – Recoil – UP to high-point – AND – Contact -- ..
World reference frame - Outside observer Contact foot is stationary on the ground. (otherwise you fall)Back foot advances quickly to catch next contact. Local reference frame - View from camera following the character Contact foot moves backward relative to body center.Back foot advances at same rate that contact trails. http://www.idleworm.com/how/anm/02w/walk1.shtml
World Reference Frame Left foot, Right foot, and Body Incorrect versionCan you tell what’s wrong with this?Can you tell which foot is which?
World Reference Frame Left foot, Right foot, and Body Correct versionWhat’s different? Why?
Now back foot iscontact foot. Contact foot stays plantedon the ground. Linear interpolation keeps it flat. Whole bodytranslates forwardlinearly. Back foot eases up to the forwardlocation rapidly, but not linearly.