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CSCI480/582 Lecture 8 Chap.2.1 Principles of Key-framing Techniques Feb, 9, 2009. Outline. Managing data with time dimension Key-framing in general Rigid Object Motion Translation of object space coordinate Parametrization - Arc length Speed control
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CSCI480/582 Lecture 8 Chap.2.1 Principles of Key-framing Techniques Feb, 9, 2009
Outline • Managing data with time dimension • Key-framing in general • Rigid Object Motion • Translation of object space coordinate • Parametrization - Arc length • Speed control • Acceleration control - Ease-in/Ease-out
Managing data with time dimension • Data in 3D scene • Vertex positions • Vertex Color/Material • Light source locations/parameters • Texture image/coordinate • Model transformations • Camera locations – view transformations • Any data or OpenGL pipeline configurations can be changed along the time axis
Key-framing technique in general • A certain time frames are picked out as key-frames • Key-frames are defined manually which usually holds main sketches of the dynamics in the animation • The rest frames in between adjacent key-frames are created automatically using interpolations
Key-framing examples Start Frame End Frame Linearly Interpolated Animation Start Frame End Frame Linearly Interpolated Animation Start Frame End Frame Linearly Interpolated Animation
Key-framing Applied to three typical motions • Rigid-body motion • Vertex geometric properties does not change relative to the object coordinate space • Motion can be described as a function of ModelView matrix to time • Object deformation • Vertex geometric properties change relative to the object coordinate space • Non-geometric motion • From material, color, light property, texture
Rigid Body Motion Yw Object Space Xw Zw World Space • Geometric transformations of the object coordinate system in the world space define rigid body motion • Further decompose the object coordinate transformations into • Translation: a point moving in a 3D world space • Rotation: vector orientations in a 3D world space
Rigid Body Motion – Parametrization by Arc Length along a curve 1D: 3D: • Arc length refers to the length of the curve from a point P(u1) to another point P(u2) • Speed control by • Arc-length relative to time • Acceleration: Ease-in / Ease-out for natural motion