This paper presents a portable optical measurement system for capturingcontinuous key motion on any piano. Very few concert venues have MIDI-enabledpianos, and many performers depend on the versatile but discontinued MoogPianoBar to provide MIDI from a conventional acoustic instrument. The scannerhardware presented in this paper addresses the growing need for alternativesolutions while surpassing existing systems in the level of detail measured.Continuous key position on both black and white keys is gathered at 1kHz samplerate. Software extracts traditional and novel features of keyboard touch fromeach note, which can be flexibly mapped to sound using MIDI or Open SoundControl. RGB LEDs provide rich visual feedback to assist the performer ininteracting with more complex sound mapping arrangements. An application ispresented to the magnetic resonator piano, an electromagnetically-augmentedacoustic grand piano which is performed using continuous key positionmeasurements.