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Gary
For my area the data returned from the currently hardcoded "reverse-geocoding" sites is commonly, either misleading, or too general.

Geoname.org often returns the names of old western "ghost-towns". These are not really helpful as a reference, since they seldom appear on current maps. Because much of my area is rural, Google Earth often gives me designations referring to electoral boundaries. Again, this is less than helpful.

The most obvious and most easily implemented solution would be the following. Have a method of entering a "reverse-geocoding" site URL with the appropriate command parameters,  such that other "reverse geocoding" databases could selected and then referenced during "reverse geocoding". I have seen this done in other geo-tagging apps.

However; there is another very robust solution that comes to mind. Call this a "pipe-dream", because it might take a bit of work to implement in code. Allow a user to define their own table of named local regions (ie. Banff National Park or Spray Valley Provincial Park), defined by a user-specified polygon of coordinates. Give this table priority over external lookups. If the geo-tagging coordinates fell within the polygon, the specified Regional Name would be returned as the City, plus the Province/State, and Country specified in the record. One could even allow an average elevation to be specified in the table as a default. The user would need to do a bit of work once, but they would recoup that many times over. 

Regards;
Gary
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houdah
Hi!

Thank you for the suggestion.

Do you have any particular reverse geocoding services in mind?

Best,
Pierre Bernard
Houdah Software s.à r.l.

Houdah Software s. à r. l.
https://www.houdah.com

HoudahGeo: One-stop photo geocoding
HoudahSpot: Advanced file search utility
Tembo: Easy and effective file search
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Gary
Hi Pierre;

I'll try to prepare a list of sites and will send them to you.

In the meantime, here is a site that supplies polygons defining the boundaries of regions within a country. Seems that I'm not the first to have that idea and that it is not a "pipe-dream" after all. It supplies them in many formats, including a database and kml. Makes using them quite a bit easier.


There is also a very nice site that you and other users may wish to explore. It has a very wide variety of GIS-related tools and data sources. All of them are free.


Regards;
Gary

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Gary
Hi Pierre;

I've tried to find some alternative, free, online databases. The links I've tried in past are no longer active or have the queries throttled based on your IP address. However; I'll keep looking. More and more sites are looping things back through Geonames, Google Maps, or GoogleEarth. This is unfortunate, as their reverse-locations are sometimes not all that good.

Here is something you might find interesting. In looking for sites, I came across the following article. 

(http://www.johnsample.com/articles/GeocodeWithSqlServer.aspx)

The fellow is using a local sql server and freely available "Tiger" line data files to do geocoding and reverse geocoding. It appears that he supplies the necessary interface code to do lookups and reverse-lookups free of charge.

This approach could solve a common complaint of people who don't have an internet connection to do reverse geocoding. It's all self-contained. Could really be nice when one takes a lap-top on a field-trip.

When time permits, I might download things and evaluate the accuracy of his reverse geocoding.

Regards;
Gary

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houdah
Hi!

Thanks for the follow-up.

The proposed solution unfortunately has quite a few limitations. E.g. the data needed for this must first be found and downloaded to the users' machines. Data for the UK is very unlikely to be available, …

I will keep exploring solutions to improve upon the current reverse geocoding.

It might be a good idea to let the user build up a list of favorite places and link to one of those as long as the photo falls within reasonable range.

Best,
Pierre Bernard
Houdah Software s.à r.l.

Houdah Software s. à r. l.
https://www.houdah.com

HoudahGeo: One-stop photo geocoding
HoudahSpot: Advanced file search utility
Tembo: Easy and effective file search
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Gary
Hi Pierre;

What you suggest is very similar to the database of polygons approach that I noted in my first email.

The only slight difference is that the "polygon approach" doesn't rely on the shortest distance between two points to determine a match. That approach may be failing, because you need both distance and direction to reduce the number of degrees of freedom for the set of potential solutions. This where most reverse geocode sites appear to fall down and why they may be choosing an incorrect location name.

The proposed method would look for the coordinates of the point to be within a user-defined polygon of n points of a 2-D plane. The algorithm to determine a match is not likely to be as straight forward as the usual approach, but would be "deadly" accurate. For a localized area, the extra work is a one-time effort and pays a continuing dividend for any who do a lot of shoots in a certain locale. If you'd like, I'll see if I can find a variant of the algorithm that is suitable and potentially easy to code.

Regards;
Gary
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