Tap pressure strength detection using accelerometer

Question

Yesterday, in the presentation about the new Garageband for iPad 2, Apple demoed an interesting feature: The detection of the tap pressure by using the accelerometer. (See t

Answer 1

viggio24 is right. finger-area sensing works fine. (i have some posts here with the trivial line of code to get it). the only problem is that it's not clear what the consequences are if you ship with it enabled; we assume that it simply won't be approved in the best case.

Answer 2

Perhaps it's due to the more sensitive gyroscope? Combined with Accelerometer data, it's probably reasonably easy to determine even small changes in movement. Just a hunch. Unless there's something they're not telling us, which wouldn't be a first.

Answer 3

Well simply do this experiment:

open with XCode the AccelerometerGraph tutorial app included in the XCode bundle. Then start the app (High Pass filter, better using Adaptive filtering): you will see the blue line changing according to the strength of the app. Of course this is affected by trembling in the table, which adds noise to the measure, but you can still filter it by checking the accelerometer data with the touch event.

So this kind of pressure detection is possible using the accelerometer.

Answer 4

Tap area size detection? (Harder tap, larger fingerprint) Tap dynamics?

Just thinking.

Answer 5

I imagine that the aluminium case and the table don't prevent from very small movements and that the sensor is very sensitive.

Or, Garage Band user experience is better with iPad standing on the Smart Cover.

Answer 6

Even if the SDK exposes to us the touch area only, I believe the screen hardware is providing to the operating system much more info: touched pixels (used for area detection) and touch duration. Together (and experimenting) they can give you a good estimate of the applied pressure. It would be nice if Apple were releasing this empirical pressure estimation to developers.