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

Mike Liebhold mnl at well.com
Fri Aug 28 16:34:54 PDT 2009


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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>>   
>>     
>
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