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Re: Sensor API feedback: OrientationData

From: Doug Turner <doug.turner@gmail.com>
Date: Fri, 2 Mar 2012 11:12:17 -0800
Message-Id: <2904F2E4-4279-4474-9C15-9BB2CC589D8F@gmail.com>
To: public-device-apis@w3.org
Hi Jonas, Tran,

I am concerned that there is overlap between the Sensor Api and the DeviceOrientaiton Spec:

I worry that web developers will not know which API to use.  Tran, have you looked at our draft specification?  I am wondering how we can make these two efforts result in something that is consistent and pleasing to developers.

Answer to questions Jonas raised:

> I'm having trouble understanding the difference between the OrientationData and AccelerationData sensors.

They are measuring different things.  Orientation has to do with rotation about an axis measured by a gyro.  Acceleration will tell you change in speed measured by an accelerometer. 

> it's impossible to tell the difference between gravity and acceleration.

True. http://en.wikipedia.org/wiki/Equivalence_principle

> is the OrientationData sensor simply a convenience function on top of the AccelerationData sensor?

Both tell you something about the reference.  You really want to know both acceleration and orientation to fully understand what is happening to the reference.  You can't always determine orientation from acceleration or visa versa.

> Could someone explain the meaning of the alpha, beta and gamma values?

The DeviceOrientation spec goes into great detail about what these values are.
Received on Friday, 2 March 2012 19:12:45 UTC

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