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1 Projects Projects Final Reports Final Report Textual - PDF document

Mar 12, 2024 •391 likes •512 views

Paper Summaries Any takers? Sound and Animation This week is the last week for paper summaries. Projects Assignments and such Presentations Grading Schedule is now up on Web site Keyframing most should have gotten

  1. Paper Summaries � Any takers? Sound and Animation � This week is the last week for paper summaries. Projects Assignments and such � Presentations � Grading � Schedule is now up on Web site � Keyframing – most should have gotten � All projects have been scheduled! mail from me. � Please check date you are to present � Billiards – some should have gotten mail � Grad reports from me. � Next week � Final Presentation schedule – now final! � Please check date you are to present � Please include README files!!! Assignments and such Plan for Articulated Figure Motion � Articulated Figure Motion � Last week � Monday, Feb 6th � Today: Intro / Forward Kinematics / Spacetime Constraints � Group animation (flocking / particle) due � Wednesday: Inverse Kinematics � Hey the dropbox was left open! � This Week � Monday: Motion Capture / Assignment # 4 � Wednesday, Feb 15 th � Wednesday:Advanced Techniques in Articulated Figure � moCap assignment due Motion (using GAs /Procedural Methods) � Next week � Character animation / Guest Lecture on Falling � Sound & Animation 1

  2. Projects Projects � Final Reports � Final Report � Textual description of your system � Note that final reports / code are � Sections SEPARATE grading components � Problem/Project Description � Approach � Final reports/code are due on the last day � Implementation of class (March 2nd) � Overall System Architecture. � Overall Program Architecture � Note this is a hard deadline � Description of major data structures / objects � Dropbox is set up for report and code � Results / User Documentation submissions. � Future Enhancements � Appendix -- All Code listings Plan for today Motivation Films � Sound and Animation � Animations by Wayne Lytle � Visualization Guru at Cornell Theory Center � Quit to start Animusic in 1995 Motivational Film Motivational Film � More Bells and Whistles (1990) � Pipe Dream (2001) � Lytle wrote the the code for each band � Animusic member � Can’t See too much Animusic � Motion is MIDI controlled � Sound drives motion � First of several Animusic pieces to be shown at SIGGRAPH 2

  3. Motivational Film Motivational Film � Train Wreck (2003) � Geri’s Game (1997) � Martin Burolla � Technical challenge: Human & Clothing Modeling � From animation class (20022) � Geri makes a cameo appearance in Toy Story II. Sound and Animation Sound � Issues in Sound and Animation � What is sound? � Sound Generation � From webster.com � What do we play? � mechanical radiant energy that is transmitted by longitudinal pressure waves in a material � Sound Synchronization medium (as air) and is the objective cause of � When do we play? hearing � Spatial Sound � Where do we play Sound Remember this? � What is sound? � Spatial vs frequency domains � Sound can be described as a 1 dimensional � Most well behaved functions can be signal in time described as a sum of sin waves (possibly offset) at various frequencies � Describing a function by the contribution sound = f(t) (and offset) at each frequency is describing the function in the frequency domain 3

  4. Sound Sound � A mathematical description of an audio signal: ∞ = ∑ π ω + φ f ( t ) A sin( 2 t ) i i i = i 0 Contribution/amplitude frequency phase Foley/VanDam Sound: Loudness Sound: Pitch � Looking at sound in the temporal � Looking at sound in the frequency domain domain. � Sound can be described as a 1 dimensional � Humans “hear” sounds because of signal in time periodicities in the audio signal. � Humans perceive frequency as the sensation of pitch. � Signal values represent amplitude. � Humans can perceive pitches due to periodicities ranging from 20 – 20000 � We perceive the effect of amplitude as vibrations / sec (Hz). loudness. Sound: Pitch Sound: Timbre � Tone quality of a sound � Remember our discussion of CD audio � Formally defined as � sampling rate of 44,100 samples/sec � ∆ = 1 sample every 2.26x10 -5 seconds � Characteristic of sound not due to amplitude and pitch. � CDs can accurately reproduce sounds with � Also defined frequencies as high as 22,050 Hz. � Quality of tone that distinguishes between musical instruments � Sound shape 4

  5. Sound: Timbre Sound: Summary � Timbre is the perception of the Physical Perceptual “spectral makeup” of a signal. Characteristic Characteristic � Adding non-fundamental frequency to the Amplitude Loudness signal. Frequency Pitch � Another annoying audio applet – Timbre Spectral “shape” Timbre Sound Generation Sound Generation � So how does one generate sound for � When talking about digital (sampled animation? sound) � Easiest means � The process of digitizing is called pulse code modulation (PCM). � Recording / Sampling -- Still the primary means for sound generation in the film industry � PCM = = sampled sound � Using sampled sound – Still the primary means � WAV for sound use in games. � AIFF � MP3 (compressed PCM) Sound Generation Sound Generation � Subtractive Synthesis � Additive Synthesis ∞ ∞ = ∑ = ∑ π ω + φ π ω + φ f ( t ) A sin( 2 t ) f ( t ) A sin( 2 t ) i i i i i i = = i 0 i 0 � Define values for A i , ω i , and φ i � Start with noise (equal energies at all � Calculate sin and add frequencies) � Alternately, do in the addition in frequency � Subtract contribution of frequencies space. from noise. 5

  6. Sound Generation Sound Generation � Granular Synthesis � Using physically based models � Like particle system � SIGGRAPH 2001 Videos � Combine a multitude of sound “grains” into a sound events � Questions Sound Synchronization Sound Synchronization � Sound driving motion � Sound must be synchronized to the � MIDI motion � Designed as a communication mode between � Methods: sythesizers, samplers, instruments, computers � Sound events � Motion driving sound � Pitch � Defining Sound events � Devices � Deriving timbre from motion � Used by Animusic in creating their videos � Sound driving motion � Example video from Bingo guys. Spatial Sound 3D Sound � Sounds (and listeners) have spatial positions � Making sounds appear as if they are � 3D sound emitted from a given position � Making sounds appear as if they are emitted from a accounting for listener position given position accounting for listener position � Head related transfer functions (HRTF) � Reverberation � Filtering of sound based on reflection off of environment � Audio cubes / surround sound � Doppler Effect � Strategic placing of speakers � Change in pitch due to moving objects 6

  7. 3D Sound: HRTF 3D Sound: HRTF � a description of all the physical cues of sound localisation. � Implemented as filters � function of four variables: ie three space coordinates and frequency. � Determined by measurement Anderson/Casey 3D Sound: HRTF 3D Sound: reverberation � Like light, sound can be seen as traveling in 3D environment in rays. � Unlike light, sound travels much slower � Speed of sound: � Speed of light Anderson/Casey 3D Sound: reverberation 3D Sound: reverberation � Reverberant sound is � Examples the collection of all the � From BKL Consultants Ltd. reflected sounds in an (http://www.bkla.com/reverb.htm) enclosed space � No reverb � Acoustics � 0.8 sec reverb time � Reverb Time = time � 1.5 sec reverb time required for sound to � 5.0 sec reverb time decay one millionth of the original power � One more SIGGRAPH video 7

  8. 3D Sound: Doppler effect 3D Sound: Doppler effect � Non-annoying applet break Sound: Putting It all Together Sound: Putting It all Together � Sound Rendering Video Examples Takala/Hahn Remember CGII: Procedural Approaches to sound generation Shading � Shade Trees [Cook84] � Hueristic � Shading calculated by combining basic � Whatever sounds good. functional operations. � Physically Based � Operations are organized in a tree. � Analysis of vibration � Nodes - Operations � Children - operands � Emperical data � Result of shade tree evaluation is a color � Sampled Sound � Equiv to parse tree (compiler design) � Basis of Renderman shading language. 8

  9. Remember CGII: Procedural Remember CGII: Procedural Shading Shading � Shade Trees - example…copper � Basic ideas behind shade trees: � Describe textures / shading functionally � Using Parameters from 3D world � Can we use a similar model for sound? [Cook84] Timbre Trees Timbre trees � Functional sound synthesis � Sound related functions � Periodic functions � Convolution � Noise � Filtering � Nodes for animation, 3d parameters Hahn/Geigel. Et al Timbre trees Timbre trees � Nodes could also be used to simulate: � Reverberation � Delay � Spatial Sound Hahn/Geigel. Et al 9

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