[X3D-Public] Accelerometer environment sensor

Don Brutzman brutzman at nps.edu
Fri Nov 20 13:58:27 PST 2009

Keith Victor wrote:
> Hey Don:
> I agree that an orientation_changed output field would be helpfull in 
> addition to the raw acceleration data.  For true 3D orientation, you 
> would also need compass input along with the accelerometer.  Or, is this 
> the 2D orienation, as I had described.  We need to clearly define this.

agreed.  another limitation is that you don't have a "fix" capability
to know where "zero" or "north" or "origin default orientation" might be.
Hence thus suggestion to define default orientation based on when
enabled field becomes true.

> In an ideal world, you can integrate acceleration to get relative 
> velocity.  And, once again to get relative position.  But, Im afraid 
> thats not going to work with these simple devices.  The acceleration of 
> gravity is so much stronger than anything else going on, that the only 
> thing it is good for is detecting the orientation of the device ( which 
> way is down ), and any extreme shaking.  You're not going to get any 
> good velocity data out of an iPhone ;(

that is a good question that is worth further checking - who can do that?

> What is the "IsActive" output field do?  Does that tell you if the 
> device supports this feature.  If its enabled, and working, its going to 
> be active. Perhaps SFBool isSupported   is a better name.

isActive is required as part of the X3DSensor abstract interface.
so applying your definition in this context sounds appropriate.

all the best, Don
Don Brutzman  Naval Postgraduate School, Code USW/Br           brutzman at nps.edu
Watkins 270   MOVES Institute, Monterey CA 93943-5000 USA  work +1.831.656.2149
X3D, virtual worlds, underwater robots, XMSF  http://web.nps.navy.mil/~brutzman

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