RE: Position Heading Questions?

Angel,

 

I did read (and notice) your original email.  I have to point out that facing/azimuth includes the elevation angle.  However, it doesn’t necessarily mean that both have the same cost-benefit.  Horizontal does tend to be more useful.  Each parameter that you add increases complexity.  (Although I’m not certain that holds true after discovering that some cities have multiple layers.)

 

There are an arbitrary number of parameters that could be added.  The real trick is to find the set that is important.  I tend to think that (at least initially) a vertical angle isn’t going to be of much use.

 

Cheers,

Martin 

 

From: Angel Machín [mailto:angel.machin@gmail.com] 
Sent: Monday, 17 November 2008 4:37 AM
To: Thomson, Martin
Cc: Greg Bolsinga; public-geolocation
Subject: Re: Position Heading Questions?

 

Hi Greg, Martin

 

It has been already proposed, please read this thread: http://lists.w3.org/Archives/Public/public-geolocation/2008Oct/0017.html


 

I suggested (with little success :-) ) the use of two new parameters, the "facing" or azimuth (taken from the compass) and the "elevation angle" (taken from accelerometers) corresponding to the horizontal coordinate system (http://en.wikipedia.org/wiki/Horizontal_coordinate_system) <http://en.wikipedia.org/wiki/Horizontal_coordinate_system> 

 

I know it is not exactly location, it is device orientation, but it could be useful for some location-aware applications. It could be used for example to identify stars or constellations in a hypothetical sky-map system or any "point-to-identify" application.

 

Regards,

 

Angel

 

On Sun, Nov 16, 2008 at 5:14 PM, Thomson, Martin <Martin.Thomson@andrew.com> wrote:

Hi Greg,

We've addressed a similar problem in the IETF [1].

Essentially, there are use cases for having both.  Best example I know of is where someone is travelling past a store in a car.  They point their device at the store and press the "what store is that" button.  I know that this sort of thing is already used in some places.  Having both pieces of information is very useful.  Either one on its own might be misleading.

My proposal:

facing // 0th order: degrees
speed // 1st order: m/s
heading // 1st order: degrees

The referenced draft currently has two more, but those are still being debated and might be removed:

acceleration // 2nd order: m/s
acceleration heading // 2nd order: degrees

Cheers,
Martin

[1] http://tools.ietf.org/html/draft-singh-geopriv-pidf-lo-dynamic



> -----Original Message-----
> From: public-geolocation-request@w3.org [mailto:public-geolocation-
> request@w3.org] On Behalf Of Greg Bolsinga
> Sent: Saturday, 15 November 2008 3:47 PM
> To: public-geolocation
> Subject: Position Heading Questions?
>
>
> Hello --
>
> The Position object has a heading field. It is described as: "The
> heading attribute denotes the direction of the hosting device". Is
> this the heading of the vector of travel while moving, or the
> direction the user is currently facing, no matter the direction of
> travel? The context of the following field, speed, seems to indicate
> that this is the heading of the direction of travel.
>
> However, I can see the use for a 'which way is the device oriented'
> compass-style heading, as well as the direction you're traveling in.
> One can be facing backwards to the direction of travel! :)
>
> What do you think? I think having both fields is fun, but I'm not sure
> what heading has to do with a location specification if I was going to
> be really picky about it. :) No matter what, I think the Position
> object's heading description needs to be clarified. I'd also like both
> types of headings to be available, both with the "If the
> implementation cannot provide speed information, the value of this
> attribute must be null." wording.
>
> Thanks,
> -- Greg
>
>

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