CS559: PC Representation.


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CS559: PC Design Address 36: Activity Li Zhang Spring 2008 Slides from Brian Curless at U of Washington Today PC Liveliness, Molecule Frameworks Perusing
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CS559: Computer Graphics Lecture 36: Animation Li Zhang Spring 2008 Slides from Brian Curless at U of Washington

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Today Computer Animation, Particle Systems Reading (Optional) John Lasseter. Standards of conventional activity connected to 3D PC liveliness. Procedures of SIGGRAPH (Computer Graphics) 21(4): 35-44, July 1987. http://portal.acm.org/citation.cfm?id=37407 (Optional) WILLIAM T. REEVES, ACM Transactions on Graphics, Vol. 2, No. 2, April 1983 http://portal.acm.org/citation.cfm?id=357320

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Particle framework diff. eq. solver We can comprehend the development of a molecule framework again utilizing the Euler technique: void EulerStep ( ParticleSystem p, drift DeltaT ){ ParticleDeriv (p,temp1);/* get deriv */ScaleVector (temp1,DeltaT)/* scale it */ParticleGetState (p,temp2);/* get state */AddVectors (temp1,temp2,temp2);/* include - > temp2 */ParticleSetState (p,temp2);/* overhaul state */p->t += DeltaT;/* upgrade time */}

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N x v P Bouncing off the dividers Handling crashes is a helpful extra for a molecule test system. For the present, we’ll simply consider straightforward point-plane crashes. A plane is completely indicated by any point P on the plane and its ordinary N .

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N x v P Collision Detection How would you choose when you’ve reached the plane?

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x v Normal and tangential speed To figure the impact reaction, we have to consider the typical and tangential segments of a particle’s speed. N P

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Collision Response v ’ v after before The reaction to crash is then to instantly supplant the present speed with another speed: The molecule will then move as indicated by this speed in the following timestep.

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Collision without contact all in all, we don’t test minutes in time when particles are in careful contact with the surface. There are a mixed bag of approaches to manage this issue. A basic option is to figure out whether a crash more likely than not happened before, and after that imagine that you’re right now in careful contact.

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Very straightforward crash reaction How would you choose when you’ve had an impact? N x 3 v 3 x 1 v 1 P x 2 v 2 An issue with this methodology is that particles will vanish under the surface. Likewise, the reaction may not be sufficient to convey a molecule to the opposite side of a divider.

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More confounded impact reaction Another arrangement is to change the upgrade plan to: recognize the future time and purpose of crash mirror the molecule inside of the time-step N x v P

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Generate Particles Particle Attributes starting position, beginning speed (both pace and heading), introductory size, beginning shading, introductory straightforwardness, shape, lifetime. WILLIAM T. REEVES, ACM Transactions on Graphics, Vol. 2, No. 2, April 1983

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Generate Particles Particle Attributes starting position, introductory speed (both rate and heading), beginning size, starting shading, starting straightforwardness, shape, lifetime. WILLIAM T. REEVES, ACM Transactions on Graphics, Vol. 2, No. 2, April 1983

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Generate Particles Particle Attributes beginning position, starting speed (both pace and bearing), introductory size, introductory shading, beginning straightforwardness, shape, lifetime. WILLIAM T. REEVES, ACM Transactions on Graphics, Vol. 2, No. 2, April 1983

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Generate Particles Initial Particle Distribution Particle chain of command, for instance Skyrocket : firecracker Clouds : water drops

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Throwing a ball from a robot arm Let’s say we had our robot arm sample and we needed to dispatch particles from its tip. How might we compute beginning rate? Q=R(theta)*T1*R(phi)*T2*R(psi)*P We need dQ/dt

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Principles of Animation Goal : make characters that move in a persuading manner to impart identity and state of mind. Walt Disney added to various standards. ~1930 Computer representation artists have adjusted them to 3D liveliness. John Lasseter. Standards of conventional activity connected to 3D PC movement. Procedures of SIGGRAPH (Computer Graphics) 21(4): 35-44, July 1987.

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Principles of Animation The accompanying are an arrangement of standards to remember: 1. Squash and stretch 2. Organizing 3. Timing 4. Reckoning 5. Complete 6. Optional activity 7. Straight-ahead versus posture to-stance versus blocking 8. Circular segments 9. Moderate in, moderate out 10. Embellishment 11. Bid

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Squash and stretch Squash : level an item or character by weight or by its own energy. Stretch : used to expand the feeling of velocity and stress the squash by complexity. Note: keep volume steady! http://www.siggraph.org/instruction/materials/HyperGraph/movement/character_animation/standards/squash_and_stretch.htm http://www.siggraph.org/training/materials/HyperGraph/activity/character_animation/standards/bouncing_ball_example_of_slow_in_out.htm

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Squash and stretch (cont’d)

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Squash and stretch (cont’d)

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Anticipation An activity has three sections: expectation, activity, response. Anatomical inspiration: a muscle must reach out before it can contract. Watch: bugs-bunny.virtualdub.new.mpg Prepares gathering of people for activity so they recognize what\'s in store. Coordinates group of onlookers\' consideration.

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Anticipation (cont’d) Amount of suspicion (consolidated with timing) can influence view of velocity or weight.

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Arcs Avoid straight lines subsequent to most things in nature move in bends.

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Slow in and moderate out A slowing so as to amaze posture can be underlined down as you get to it (and as you abandon it). By and by, numerous things don\'t move suddenly yet begin and stop bit by bit.

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Exaggeration Get to the thought\'s heart and underline it so the gathering of people can see it.

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Exaggeration Get to the thought\'s heart and stress it so the group of onlookers can see it.

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Appeal The character must intrigue the viewer. It doesn\'t need to be charming and cuddly. Plan, straightforwardness, conduct all influence offer. Illustration: Luxo, Jr. is made to seem uncorrupt. http://www.youtube.com/watch?v=HDuRXvtImQ0&feature=related

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Appeal (cont’d) Note: dodge flawless symmetries.

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Appeal (cont’d) Note: keep away from immaculate

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