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

Sat Aug 29 09:38:16 PDT 2009

> whats the problem here? Its simple coordiante transformation stuff... or 
> do I miss something?!

PS

There is a substantive issue here to do with local coordinate systems.  When 
representing the features of a particular object it is sometimes useful to 
employ coordinates local to that object, and represent separately the 
position of the object in the world or relative to its parent in a 
heirarchy. Reasons: The  coordinates of features relative to the object may 
be known more accurately than global position of the object, and an AR 
device's relative position to the object might also be known with greater 
precision than its global position.  The object may not have a fixed 
position (eg AR on board a ship). The representation is more compact.

3d modeling formalisms support this (and full GML does too), but  GeoRSS, 
GeoJSON, and KML do not. This is probably an argument for going to 
represententations  built for 3d in the first place for AR applications 
where local coordinates play a necessary role, but concievably there is a 
niche for our lightweight geo standards extended  by addition of a 
transformation node.

-- Chris

----- Original Message ----- 
From: "Christian Willmes" <c.willmes at uni-koeln.de>
To: "Mike Liebhold" <mnl at well.com>
Cc: "Ron Lake" <rlake at galdosinc.com>; "geojson" <geojson at lists.geojson.org>; 
<geowanking at geowanking.org>; "GeoRSS" <georss at lists.eogeo.org>
Sent: Friday, August 28, 2009 6:00 PM
Subject: Re: [Geowanking] [georss] [Geojson] simple 3D geocode for AR

> Hi,
>
> whats the problem here? Its simple coordiante transformation stuff... or 
> do I miss something?!
>
> The device gets the geocoordinates from the web, and computes those using 
> its own position and orientation to local camera coordinates....
>
> its that simple... I think. ;-)
>
> regards,
> Christian
>
> Mike Liebhold schrieb:
>> Ron Lake wrote:
>>> The most logical coordinate
>>> system for locating such items is a rectilinear coordinate system (x-y-z
>>> frame) centered (origin) at the focal point of the camera.
>> What's the use case?
>>
>> In most cases, we probably can assume that the geo-annotations exist 
>> independent of the viewpoint; e.g. a viewer should be able to see the 
>> note attached to a restaurant from any perspective as they pass on a 
>> sidewalk, or drive by.
>>
>> In that case, we need absolute coordinates, not relative to the camera 
>> perspective.
>>
>> imho
>>
>> Mike
>>> Cheers
>>>
>>> Ron
>>>
>>>
>>> -----Original Message-----
>>> From: Mike Liebhold [mailto:mnl at well.com] Sent: August 28, 2009 2:05 PM
>>> To: Ron Lake
>>> Cc: Joshua Lieberman; geowanking at geowanking.org; geojson; GeoRSS
>>> Subject: Re: [georss] [Geojson] simple 3D geocode for AR
>>>
>>> Ron Lake wrote:
>>>> The use of geographic coordinates for [location of things in the field
>>> of view relative to the camera] likely does not. [ make sense]
>>>
>>> Ron,
>>>
>>> This is really counter intuitive, Can you explain what you mean?
>>>
>>> - Mike
>>>> -----Original Message-----
>>>> From: georss-bounces at lists.eogeo.org
>>>> [mailto:georss-bounces at lists.eogeo.org] On Behalf Of Joshua Lieberman
>>>> Sent: August 28, 2009 11:03 AM
>>>> To: geowanking at geowanking.org
>>>> Cc: geojson; GeoRSS
>>>> Subject: Re: [georss] [Geojson] simple 3D geocode for AR
>>>>
>>>> In both GeoRSS GML and GeoJSON, some explicit CRS needs to be specified 
>>>> to use 3-coordinate locations. The simplest one for GeoRSS seems to be 
>>>> epsg:4979 ( urn:ogc:def:crs:EPSG:4979 ). It would need a slight 
>>>> modification to support the GeoJSON long-lat encoding. Otherwise use 
>>>> GeoRSS Simple and the elev property.
>>>>
>>>> e.g.
>>>>
>>>> <georss:elev>346</georss:elev>
>>>> <georss:point>42.3234 -173.234134</georss:point>
>>>>
>>>> Well-known text description of 4979
>>>> (http://spatialreference.org/ref/epsg/4979/ )
>>>> GEOGCS["WGS 84", DATUM["World Geodetic System 1984", SPHEROID["WGS
>>> 84",
>>>> 6378137.0,298.257223563, AUTHORITY["EPSG","7030"]], 
>>>> AUTHORITY["EPSG","6326"]], PRIMEM["Greenwich",0.0, 
>>>> AUTHORITY["EPSG","8901"]], UNIT["degree",0.017453292519943295], 
>>>> AXIS["Geodetic latitude",NORTH], AXIS["Geodetic longitude",EAST], 
>>>> AXIS["Ellipsoidal height",UP], AUTHORITY["EPSG","4979"]]
>>>>
>>>> Josh
>>>>
>>>> On Aug 28, 2009, at 1:05 PM, Ron Lake wrote:
>>>>
>>>>> Sorry my example should have been
>>>>>
>>>>> <Point id = "P1" CRS = "http://www.blah.bla/standardCRS.xml">
>>>>> <coordinates>100 200 150</coordinates>
>>>>> </Point>
>>>>>
>>>>> But the argument is the same. Similar encodings can be made in JSON
>>>>> etc.
>>>>>
>>>>> R
>>>>>
>>>>> -----Original Message-----
>>>>> From: georss-bounces at lists.eogeo.org
>>>>> [mailto:georss-bounces at lists.eogeo.org] On Behalf Of Andrew Turner
>>>>> Sent: August 28, 2009 9:57 AM
>>>>> To: geowanking at geowanking.org; GeoRSS; geojson
>>>>> Subject: Re: [georss] [Geojson] simple 3D geocode for AR
>>>>>
>>>>> Simplest?
>>>>>
>>>>> Just include a 3rd coordinate in GeoRSS-Simple point or GeoJSON
>>> point.
>>>>> No, this is not explicitly valid. But you see where that discussion
>>>>> gets us. Long windy roads of elusive semantic talk (arguably
>>> necessary
>>>>> in the lon term, but not simple or useable *now*, which is when
>>> people
>>>>> are building these tools).
>>>>>
>>>>> If we lose interest without achieving a near term concensus,
>>>>> developers will just do arbitrary, different solutions. Give them a
>>>>> simple answer now, even if it makes your strict-validation-only-skin
>>>>> crawl just a little bit. :)
>>>>>
>>>>> So I say just do it, and we'll catch up with documenting it as uses
>>>>> emerge.
>>>>>
>>>>> Also, KML already supports 3D points.
>>>>>
>>>>> Andrew
>>>>>
>>>>>
>>>>>
>>>>> (via mobile)
>>>>>
>>>>> On Aug 27, 2009, at 4:35 PM, Mike Liebhold <mnl at well.com> wrote:
>>>>>
>>>>>> A friend wrote me with a request for clarification on a topic we've
>>>>>> discussed many times here, but every time we've approached a
>>>>>> consensus the answer seems elusive.
>>>>>>
>>>>>> Many devleopers are starting to create applications for iPhones and
>>>>>> Android phones to view location specific data through the
>>>>>> viewfinder using the -imprecise- capabilities of the built in gps
>>>>>> and compass and applications platforms like Layar.
>>>>>>
>>>>>> The question:
>>>>>>
>>>>>> What is the -simplest- way to geocode a geoannotation in 3D using
>>>>>> geoRSS/Atom, geojson, KML ....?
>>>>>>
>>>>>> (Is there a practical reason why WGS '84 shouldn't be implicit, and
>>>>>> a CRS lookup NOT be required?)
>>>>>>
>>>>>>
>>>>>> _______________________________________________
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>>>>>> Geojson at lists.geojson.org
>>>>>> http://lists.geojson.org/listinfo.cgi/geojson-geojson.org
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