[Geojson] [georss] [Geowanking] simple 3D geocode for AR

[Chris Goad]

> It is not a question of just
> differencing - since we will in fact know the local coordinates much
> more accurately than the coordinates of the position of the object
> relative to the earth.

Also, as Anselm mentioned,  another hugely  important case for AR is 
multiple instancing.  The notion of  "global coordinates" of the features of 
a manufactured item that has many instances makes no sense.

And an observation: For moving objects,  the underlying reason that local 
representation is sensible is that the local coordinates of features are the 
invariant facts - facts that will remain true over indeterminate motions in 
the future, unlike global coordinates however well known at any particular 
time.

-- Chris


----- Original Message ----- 
From: "Ron Lake" <rlake at galdosinc.com>
To: "Christian Willmes" <c.willmes at uni-koeln.de>
Cc: "geojson" <geojson at lists.geojson.org>; <geowanking at geowanking.org>; 
"GeoRSS" <georss at lists.eogeo.org>
Sent: Tuesday, September 01, 2009 12:05 PM
Subject: Re: [georss] [Geowanking] [Geojson] simple 3D geocode for AR


> If precision, convenience are of no interest than yes a (x,y,z)
> Geocentric CRS will work - but differences in typical large scale
> applications will be very small.  If your application recognizes (e.g.
> image processing) some object in the environment - it would be normal to
> specify things relative to the object (e.g. labels, measures on the
> object etc) and these are more sensibly expressed in a local coordinate
> system (typically rectilinear) - you may not know the accurate location
> of the object itself (nor its orientation) - but you only care about its
> approximate location (e.g. via GPS) and then the more precise location
> of things relative to the object.  It is not a question of just
> differencing - since we will in fact know the local coordinates much
> more accurately than the coordinates of the position of the object
> relative to the earth.
>
> R
>
> -----Original Message-----
> From: Christian Willmes [mailto:c.willmes at uni-koeln.de]
> Sent: September 1, 2009 11:50 AM
> To: Ron Lake
> Cc: geojson; geowanking at geowanking.org; GeoRSS
> Subject: Re: [Geowanking] [georss] [Geojson] simple 3D geocode for AR
>
> Christian Willmes schrieb:
>> Hi all,
>>
>> every single (not moving) point on earth
> sorry, I don't know why I wrote that... You can surely also model moving
>
> objects in a Geocentric Spatial Reference Frame...
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