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Re: ISSUE-19 (point-encoding): How should we represent points? [Core FPWD]

From: Jens de Smit <jens@layar.com>
Date: Fri, 10 Jun 2011 15:58:10 +0200
Message-ID: <BANLkTikRyW5B8JXn12dd=Fj+vm4W8DYygg@mail.gmail.com>
To: public-poiwg@w3.org
Hey,

On Wed, Jun 8, 2011 at 3:23 PM, Thomas Wrobel <darkflame@gmail.com> wrote:
> I'm certainly all for efficiency when using a large number of points,
> but as I said, my concern was staying implementation neutral.
> A lot of typical use, especially for AR, wont actually be defining
> area's, but rather placing remotely linked things (ie, meshs or sound)
> at specific locations. In 3d terms this would be a pivot point or a
> single centre point - essentially the one point by which the remote
> data is placed relative too. As AR systems might not be using XML
> (indeed, mine wont be, and existing ones already seem to favour Json),
> it would be good if at least for specifying the main point there is
> key name fields defined for the geolocation values.

I've heard (on the list and on the call yesterday) arguments for both
the short, space separated form and the long, individual key form.
Brevity and conformance to GML/GeoRSS are arguments for the short
form, ease of lookups/XSLT and explicit naming of lat/lon/alt for the
latter.

Saying "let's use both" obviously places the burden on the
implementors... but I think this is still manageable, so I'd like to
see both.

> For that mater, even when specifying an area for other use, doesn't it
> still make sense to have "main" point and position the rest relative
> to that? If I'm defining the area of a building, putting the corners
> in meters relative to one lat/long is probably more efficient/easier
> then all the points as lat/longs? [/suggestion]

We've had some discussion on the call yesterday  on using relative to
offset from an absolutely located point. What also came up on the call
was to adopt GeoRSS's profile of GML for these values. That does seem
pretty nice but I wonder how easy it is to switch between coordinate
reference systems (from WGS84 to relative meters and back). The
examples I've seen from GeoRSS make it look like WGS84 is default and
every point that's in a different system needs an attribute specifying
that, that sounds like it's going to be to verbose...

Anyone with more experience who can give some insight into this?

Jens
Received on Friday, 10 June 2011 13:58:55 UTC

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