[Ssc-dev] lat long order in j3m
Harlo Holmes
harlo.holmes at gmail.com
Thu Oct 30 14:18:01 EDT 2014
elasticsearch is the tool we use to index & search submissions. this has
been in the stack since version 1.
while the data can be munged a few ways on intake, the geoJSON notation is
the one I chose:
http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-geo-distance-filter.html#_lat_lon_as_array_4
currently, the mobile client sends data in the standard lat/lng float
array; on intake, i reverse those points to subscribe to the geoJSON model.
another option could be to change the float array into an object {'lat' :
lat, 'lng' : lng}, but that is not what we do currently, and it might be
best to make that change on the mobile client rather than on the server.
On Thu, Oct 30, 2014 at 1:54 PM, David Oliver <david at guardianproject.info>
wrote:
> Harlo,
>
> I think it would be wise to distinguish between what is a standard in our
> internal data representation from what is displayed to users. I've emailed
> a friend of mine with 30 years of experience in geographic information
> systems (including ESRI, the most prominent commercial GIS) and, as I
> suspected, his views align with the majority of things you see on the web
> related to display of earth-positioning data: lat/long is the order people
> are used to seeing.
>
> I looked at the GeoJSON website and see that they use terminology not
> familiar to most normal people, but probably ingrained in actual working
> cartographers (because it maps well to the idea of the Cartesian plane):
> "easting" and "northing". In an absolutely hilarious error, this page on
> Wikipedia describes the meaning, and how to display.....then get's it
> backwards because....well, because that's what people expect: latitude,
> followed by longitude:
>
> http://en.wikipedia.org/wiki/Easting_and_northing
>
> By the way, who are "Elastic Search" and why is that of overriding
> importance to us?
>
>
>
>
>
>
> David M. Oliver | david at g <david at olivercoady.com>uardianproject.info |
> http://g <http://olivercoady.com>uardianproject.info | @davidmoliver | +1
> 970 368 2366
>
> On Thu, Oct 30, 2014 at 11:53 AM, Harlo Holmes <harlo.holmes at gmail.com>
> wrote:
>
>> Actually, the order is Lon, Lat, to conform to GeoJSON standards (which
>> is required by Elasticsearch.)
>>
>> On Thu, Oct 30, 2014 at 11:52 AM, David Oliver <
>> david at guardianproject.info> wrote:
>>
>>> Agreed - the order is LAT, LONG
>>>
>>> more info: http://www.geomidpoint.com/latlon.html
>>>
>>>
>>>
>>> David M. Oliver | david at g <david at olivercoady.com>uardianproject.info |
>>> http://g <http://olivercoady.com>uardianproject.info | @davidmoliver | +1
>>> 970 368 2366
>>>
>>> On Thu, Oct 30, 2014 at 10:53 AM, Svetlana Chirkova <schirkova at gmail.com
>>> > wrote:
>>>
>>>> Hi guys, just wanted to confirm that standard/convention of gps
>>>> coordinates ordering (lat,lon vs lon,lat)
>>>>
>>>> i always thought it was lat, lon (
>>>> http://stackoverflow.com/questions/7309121/preferred-order-of-writing-latitude-longitude-tuples
>>>> )
>>>>
>>>> but j3m is lon,lat at the moment.
>>>>
>>>> just wanted to confirm that:
>>>> - it's suppuposed to be 'long,lat'
>>>> - j3m will continie to be 'long,lat'
>>>>
>>>> ?
>>>>
>>>> where am i...
>>>>
>>>> Thanks!
>>>>
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>>>
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