GPS Location lookup is not accurate

Advanced Renamer forum
#1 : 09/10-15 22:24
John Grantman
John Grantman
Posts: 4
I read the other posts regarding the GPS location lookup and I understand the concept of finding larger locations of 1000 people or more for smaller locations. But I am having the opposite issue.

I live in Chicago, Illinois (United States) which is the 3rd largest city in the country (population over 3,000,000). I have several pictures with GPS coordinates for Chicago locations. One example is "Wrigley Field" which is a professional baseball stadium in the middle of metropolitan Chicago. The GPS data is:

41 deg 56' 50.84" N, 87 deg 39' 20.82" W

Looking up the coordinates manually shows:

3700 W Waveland Ave, Chicago, IL 60613, USA
Latitude: 41.947456 | Longitude: -87.655783

That is the correct location. However, in AdvancedRenamer when the tag <GPS City> is used it returns:

"Lincolnwood, Illinois" which is a much smaller city (population 12,697) which is 8-9 miles away. I found similar inaccuracy for several European locations from a recent trip to following cities (Cork, Dublin, Prague, Athens, Rome, Geneva, Brussels, London, Bilbao, Amsterdam).

I took over 1000 pictures over a month across these cities and the values for <GPS City> and <GPS State> are different than Google, Apple iCloud or GeoSetter when the coordinates are used to find the location.

It appears the looked up location data is "close" but just several miles off. I don't know Europe nearly as well as the US where I consistently see the same inaccurate locations.

Is there anything I can do to adjust the lookup with an offset or something to make it more accurate? Can an alternate data source be used if the issue is the database used for the lookups?

Any help is appreciated.

Overall this is a WONDERFUL tool and the GPS issue is really the only issue I have found. The core functions are excellent.

Thank you for creating this tool.


09/10-15 22:24
#2 : 11/10-15 15:33
Kim Jensen
Kim Jensen
Administrator
Posts: 756
Reply to #1:
Choosing a city is always somewhat fuzzy. Advanced Renamer use the database og GeoNames (http://www.geonames.org/) which is a very good source of GPS-tagged cities and countries. However it contains a lot of cities, maybe too many cities. The best choice of city name can be difficult to determine without a proper algorithm for excluding small cities. I don't know how google determines the city of an image, but what Advanced Renamer does is to find the nearest city with a population of 1000 or more. In your case you are more interested in another larger city located a little longer away.
My algorithm is somewhat arbitrary; any algorithm has to be. The 1000 population limit might be too low. I might also want to find the largest of the 5 nearest cities. It is difficult to choose the best algorithm for all needs.
I might add an option to Advanced Renamer where the user can choose how high the lower limit should be. In your case you could set this limit to 25000.
Do anybody know how other systems find the nearest city?


11/10-15 15:33
#3 : 19/11-15 03:38
John Grantman
John Grantman
Posts: 4
Reply to #2:

I understand the idea of limiting the lookup to larger cities but in the example I provided, the GPS coordinates are in Chicago... the 3rd largest city in the United States. However the city that is looked up is a small town near Chicago.

I found this developer site about Google reverse geocoding and put in the same coordinates and it looked up Chicago correctly.

41.947456,-87.655783

https://developers.google.com/maps/documentation /javascript/examples/geocoding-reverse

It does provide code for the lookup which may be helpful if you can use the Google API.


19/11-15 03:38