W3C home > Mailing lists > Public > public-geolocation@w3.org > March 2012

Re: Comment on Device Orientation API

From: Wolfgang Damm <wolfgang.damm@wikitude.com>
Date: Mon, 5 Mar 2012 16:37:07 +0100
Message-ID: <CAAMsROMzh_nk963x7AYK3LPyT0sMAyBnbBWtDJy=wSv2qy9PVw@mail.gmail.com>
To: Andrei Popescu <andreip@google.com>
Cc: Lars Erik Bolstad <lbolstad@opera.com>, public-geolocation@w3.org, Martin Lechner <martin.lechner@wikitude.com>
Hi all,

thanks for acting on our suggestion that quickly. We are very pleased with
the outcome and are looking forward to UAs implementing the
deviceorientation API.

Thanks,

Wolfgang

2012/3/5 Andrei Popescu <andreip@google.com>

> Hello,
>
> We discussed this issue at the face-to-face meeting today. Our
> conclusion was that it is very difficult to provide normative language
> that would force implementors to guarantee that device orientation
> events are generated for changes that are over a specific angular
> threshold.
>
> However, we do understand that the importance of ensuring that
> implementations of this spec are as similar as possible. For this
> reason, we will add non-normative language that recommends a maximum
> angular threshold of 1 degree.
>
> Thanks,
> Andrei
>
> On Thu, Mar 1, 2012 at 11:03 AM, Wolfgang Damm
> <wolfgang.damm@wikitude.com> wrote:
> > Hi all,
> >
> > my name is Wolfgang Damm and I'm working at Wikitude as Lead Software
> > Architect. In that role I'm responsible for developing an AR prototype
> using
> > the DeviceOrientation API. Let me jump right into the discussion.
> >
> > Lars, thanks for adjusting the cap.
> >
> > But, I still think that the specification needs to be reworded. The
> > pharse "significant change in orientation" is to vague and can be
> > interpreted in various ways. Even if it is problematic for our
> > usecase, Opera was still well within the specification.
> >
> > A few usecase come to my mind (and I think you have thought of a few more
> > already):
> > 1. Augmented Reality
> > 2. Games
> > 3. Determining Screen orientation (only Up, Down, left, right is of
> > interest)
> >
> > With the current specification I believe only usecase 3. is sufficiently
> > covered. For 1. and 2. it is up to the specific UA implementation if they
> > are possible.
> >
> > In my opinion, to cover the different update rate/accuracy needs of
> > different usecases without draining battery or degrading performance the
> > optimal way would be to let the web app specify how many updates/what
> > accuracy it needs. But if this is not an option, there should be a more
> > concrete wording of when events should be fired. Something in the line
> of:
> >
> > The event should be fired with a minimum update rate of around 100 ms or
> if
> > a significant change in orientation occurs.. The definition of a
> significant
> > change in this context is left to the implementation.
> >
> > By defining the update rate, a game developer knows what to expect when
> > using this API. It also helps in development that the event firing
> behavior
> > is more similar across different UAs..
> >
> > Best,
> >
> > Wolfgang
> >
> > 2012/3/1 Lars Erik Bolstad <lbolstad@opera.com>
> >>
> >> Hi Martin,
> >>
> >> Sounds like we've capped this at a too high level in Opera's
> >> implementation. We'll adjust that.
> >>
> >> Lars Erik
> >>
> >>
> >> On 29.02.2012 21:40, Doug Turner wrote:
> >>>
> >>> Hi Martin,
> >>>
> >>> Thanks for your suggestion.  This is an interesting idea, and one
> >>> that was discussed.  The draft states:
> >>>
> >>> The event should fire whenever a significant change in orientation
> >>> occurs. The definition of a significant change in this context is
> >>> left to the implementation. Implementations may also fire the event
> >>> if they have reason to believe that the page does not have
> >>> sufficiently fresh data.
> >>>
> >>> I tend to think that Opera filtering at 4 degrees is a UA bug.  Maybe
> >>> a RFE.  I do not think I want to expose tighter control here to web
> >>> application.  Surely any change to the API allowing such control
> >>> could be veto'ed by the UA.  Opera could still cap their
> >>> notifications at 4 degree changes even though the web application
> >>> asked for something tighter.
> >>>
> >>> It could also be an implementation concern.  I know when I fire lots
> >>> of events, the over all browser performance suffers.  I think UA's
> >>> need some flexibility here to provide the best possible performance.
> >>>
> >>> Thanks again,
> >>>
> >>> Doug Turner
> >>>
> >>>
> >>>
> >>> On Feb 29, 2012, at 6:46 AM, Martin Lechner wrote:
> >>>
> >>>> Dear members of the Geolocation Working Group,
> >>>>
> >>>> I am Martin Lechner, CTO of Wikitude, a member of W3C and developer
> >>>> of the Wikitude World Browser.
> >>>>
> >>>> We are currently developing an augmented reality project on
> >>>> platforms based on the DeviceOrientation API, and do have a comment
> >>>> regarding some specific items in the draft specification.
> >>>>
> >>>> The current specified update rate of the device orientation event
> >>>> is not sufficient for our usecase. Specifically the phrase: “the
> >>>> event should fire whenever a significant change in orientation
> >>>> occurs.” leaves it up to the implementation when exactly to fire an
> >>>> event.
> >>>>
> >>>> We are already seeing different implementation in the prerelease
> >>>> versions of Opera (LAB Opera Mobile) and Mozilla (Aurora). While
> >>>> Mozilla reports events quite frequently (which is preferred by us),
> >>>> Opera matches the specification and reports events only if there is
> >>>> a change of approximately 4 degrees.
> >>>>
> >>>> Our suggestion would be to let the web developer define how
> >>>> accurate the orientation changes should be reported. E.g. like the
> >>>> accuracy modes in Geolocation API. For AR it would be nice to have
> >>>> a high accuracy to achieve more events to get a smoother, more
> >>>> accurate calculation when moving the device.
> >>>>
> >>>> Best regards, Martin Lechner
> >>>>
> >>>> -- - - - Martin Lechner CTO
> >>>>
> >>>> Wikitude GmbH Ginzkeyplatz 11 5020 Salzburg/Austria Phone +43 662
> >>>> 243310 Mobile +43 676 840 856 300
> >>>>
> >>>> http://www.wikitude.com
> >>>>
> >>>>
> >>>>
> >>>
> >>
> >>
> >
> >
> >
> > --
> > Wolfgang Damm
> > Lead Software Architect
> >
> >
> > Wikitude GmbH
> > Ginzkeyplatz 11
> > 5020 Salzburg/Austria
> > Email: wolfgang.damm@wikitude.com
> > Phone: +43 662 243310
> > Mobile: +43 676 840 856 900
> > Web: http://www.wikitude.com
> > Twitter: twitter.com/Wikitude
> > Facebook: facebook.com/wikitude
> >
> > Make sure to subscribe to our developer newsletter so you don't miss any
> > update about ARchitect.
> >
>



-- 
Wolfgang Damm
Lead Software Architect

Wikitude GmbH
Ginzkeyplatz 11
5020 Salzburg/Austria
Email: wolfgang.damm@wikitude.com
Phone: +43 662 243310
Mobile: +43 676 840 856 900
Web: http://www.wikitude.com
Twitter: twitter.com/Wikitude
Facebook: facebook.com/wikitude

Make sure to subscribe to our developer
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Received on Monday, 5 March 2012 15:37:42 GMT

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