Some Common Questions about Modal Animation
Q. Is the violin really moving that way?
A. Modal Animations show the real scanned movement of a specific violin, at one specific frequency; but MUCH slower and with MUCH more motion, for clear visibility.
Q.What is a mode anyway?
A. When most objects receive a deforming impulse, they will flex and vibrate in a variety of patterns or vibration modes as they dissipate that energy. Each and every mode will vibrate best at one specific pattern and speed, or frequency. Those mode frequencies and patterns are determined by the shape, strength, density and damping, and thus determine that object’s resonance profile.
Q. How are these animations made?
A. The method is similar to the motion capture used in many animated movies. The violin is vibrated with an impulse, (usually a calibrated impact hammer), while its surface movements, or vibration spectra, are sampled at a variety of preselected points. Later these points are used to construct a virtual computer model of the violin. The relative motion of each point at any given frequency is used to animate the image. The 3D laser scans are the most advanced to date, but useful measurements can be taken with an accelerometer (a tiny motion sensor).
Q. What do the mode file names mean eg; 273hz, 545, 710, 1360 etc?
A. The MODES with animation files here are listed by HERTZ (vibration cycles per second), eg. 440 HZ = A 440. Refer to the Musical Note Frequencies document to correlate Hertz and musical pitch.
Q. Can we tell which note on the violin is caused by any specific mode?
A. Any note played on a violin string is made up of a whole series of frequencies ie; the FUNDAMENTAL frequency plus an entire series of the HARMONIC frequencies. If any of those harmonic frequencies fall ON or NEAR a resonance peak, the associated modal vibrations can radiate at that pitch. In normal playing, many modes are simultaneously activated, and it is only by means of modal analysis that individual modes can be isolated.