computer graphics: programming, problem solving, and visual communication
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Computer Graphics: Programming, Problem Solving, and Visual Communication. Steve Cunningham California State University Stanislaus and Grinnell College PowerPoint Instructor’s Resource. Dynamics and Animation. Using motion effectively in your work. An Animation Is…. - PowerPoint PPT PresentationTRANSCRIPT
Computer Graphics:Programming, Problem Solving,
and Visual Communication
Steve Cunningham
California State University Stanislaus and Grinnell College
PowerPoint Instructor’s Resource
Dynamics and Animation
Using motion effectively in your work
An Animation Is…
• A sequence of individual images that are presented over time
• The images can either be– computed separately and assembled into the
sequence later, or– computed in sequence and displayed as they are
computed (real-time animation)
• The choice depends mostly on how complex the images are and whether you want to save the sequence for re-display
An Example
• Particle systems example: four frames showing progress
• This sequence shows how particles move
Procedural Animation
• Motion is built into the model so that objects are in different places with each display– Can be based on a meaningful parameter
(such as time) or– Can just use frame-to-frame increments
Procedural Animation (2)
• Changes can be built into the model through the scene graph– Any component of the scene graph can use
a parameter or can be changed with each display
– Transformations (e.g. rotation or translation)– Geometry (e.g. number of objects or the
particular shapes used)– Appearance (e.g. color, texture, alpha)– View (e.g. eyepoint, view direction)
Procedural Animation (3)
• Interpolations give us an important kind of procedural animation
• Points can be moved along spline curves using a parameter t that is the spline curve parameter
• These points can be eyepoints, geometry points, or can even be interpreted as directions or any other 3D value
Interpolation Examples
• Texture interpolation– From the left-hand
texture to the right-hand one
• Geometry interpolation– From the left-hand
geometry to the right-hand one
Interpolation Examples (2)
• Eyepoint animation: along a spline curve with control points shown in red
Problems with Animation
• Frame rates -- making the animation look smooth– Real-time animation speed can depend on
the speed of the computer• If your user has a newer computer, the animation
may seem too fast
– Some images are so complex that real-time animation cannot be done in acceptable time
Problems with Animation (2)
• Temporal aliasing -- sampling at discrete points in time– Common example is the moving spokes
problem; a single frame is shown
Showing Motion in Static Frame
• Showing traces • Accumulation buffer
Non-Real Time Animation
• Computing frames individually and showing only finished frames avoids some of the problems with real-time animation
• Frames can be assembled with many kinds of movie-making tools
• Movie-showing software takes care of frame rates for you
• Extra work is involved in assembling the movie, however, and you cannot experiment with the animation
Non-Real Time Animation (2)
• There are other considerations if you want your animation to play on TV– For “normal” [non-HD] TV there are real
issues with image size and the YIQ color system that will be used to transmit the picture
– Look carefully at color choices and color bleeding problems