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07/10/2009 17:05:25
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ina
Joined: 07/10/2009 16:56:11
Messages: 2
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I guess I am totally stuck. To use the cities webservice, I have to enter the
"coordinates of bounding box" north, east, west, and south
I have the coordinates of a city/place e.g.
lat=52.516900
lng=13.400831
How do I "translate"?
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07/10/2009 20:53:07
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marc
Joined: 08/12/2005 07:39:47
Messages: 4412
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If you don't have a bounding box, then I don't think you want to use the cities webservice, you are probably more interested in the findNearbyPlaceName service.
http://www.geonames.org/export/web-services.html#findNearbyPlaceName
Marc
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07/10/2009 21:14:15
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ina
Joined: 07/10/2009 16:56:11
Messages: 2
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Thanks for you answer.
marc wrote:
I don't think you want to use the cities webservice, you are probably more interested in the findNearbyPlaceName service.
No, I AM interested in the cities webservice, I want to find neighborcities, ordered by population. Using findNearbyPlaceName returns all kind of stuff, even with a given featureClass or featureCode.
http://ws.geonames.org/findNearbyPlaceName?lat=52.4981713016771&lng=13.3974838256836&radius=150&featureCode=PPLA&featureCode=PPLC&featureCode=PPLG
would work, but is limited to a) some sort of capital cities and b) the radius, which can be different depending on the area (rural areas need a bigger radius to find an appropriate amount of bigger cities than highly populated areas)
How do I get a bounding box?
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08/10/2009 22:25:16
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fred_kuijper
Joined: 24/01/2008 22:08:39
Messages: 35
Location: The Netherlands
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I'm sorry for interrupting but I happened to read this,
The result is limited because PPL has not been specified:
http://ws.geonames.org/findNearbyPlaceName?lat=52.4981713016771&lng=13.3974838256836&radius=150&featureCode=PPLA&featureCode=PPLC&featureCode=PPLG&featureCode=PPL
If the radius depends on the city's population size than this data item can be requested first and used to determine the radius.
btw I don't understand the problem with the bounding box. East is lng+x and west is lng-x, north is lat+y and south is lat-y.
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Fred Kuijper
The Netherlands |
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13/10/2010 02:45:17
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nikey
Joined: 13/10/2010 02:38:20
Messages: 4
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Nevermind
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15/08/2011 06:53:43
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saad786
Joined: 14/08/2011 20:02:09
Messages: 2
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fred_kuijper wrote:
I'm sorry for interrupting but I happened to read this,
The result is limited because PPL has not been specified:
http://ws.geonames.org/findNearbyPlaceName?lat=52.4981713016771&lng=13.3974838256836&radius=150&featureCode=PPLA&featureCode=PPLC&featureCode=PPLG&featureCode=PPL
If the radius depends on the city's population size than this data item can be requested first and used to determine the radius.
btw I don't understand the problem with the bounding box. East is lng+x and west is lng-x, north is lat+y and south is lat-y.
hi, i liked your thought. but could you please explain what are the X and Y values if you say :
East is lng+x and west is lng-x, north is lat+y and south is lat-y
For example :
my latand lng values are as below:
Latitude 48.8553996
Longitude 2.3341415
How can i get
East lng + x West lng -x North lat+y Sout lat-y
what are x and y in above?
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18/08/2011 06:13:16
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saphir
Joined: 05/06/2010 22:44:39
Messages: 130
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Hi Saad
It is impossible to have a general "worldwide" number for x and y, it is up to you to determine the dimensions of the bounding boxes needed for your purposes >>>
For your Paris sample the height of the box from Orly to St-Denis should be some 25km – if you apply this big value to a rural region or a state border region, the box will contain some distinct villages or cities...
You will have to take individual or compromise distances from the center.
As fred_kuijper wrote, you may try with the city population numbers to evaluate some specific compromise distances…
In the North-South direction, one degree of latitude is invariably a distance of 60 nautical miles or 111.12 km.
For the northern bounding, you add your chosen value in decimal degrees to the center latitude… or subtract for the southern one.
For Paris with my 25km-sample or 12.5km to north and south >
48.8553996° [=Center] plus (12.5km / 111.12km) = 48.9679° for the northern limit or
48.8553996° minus (12.5km / 111.12km) = 48.7429° for the southern one
The East-West direction is neither invariable nor linear, an equatorial longitude degree is 60 nautical miles too – but a pole longitude degree is zero.
You will have to divide your chosen distance converted to degrees by the cosinus of the latitude >>> with my 25km box >
2.3341415° [=Center] plus (12.5km / 111.12) / 0.65796164 [=cosinus 48.8553996°] = 2.5051° for the eastern limit or
2.3341415° minus (12.5km / 111.12) / 0.65796164 = 2.1632° for the western one
Regards
Urs
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