Hi team,

I am looking for someone who might be able to help me understand why there are discrepencies between data entered in Location and displayed with the Gmap module, VS using maps.google.com as a normal user.

Firstly a disclosure: I have applied the user-driven "patch" at http://drupal.org/node/584014 I know this is not supported, but it brings geocoding to many countires.

You can replicate these discrepencies and see the differences:

Correct Behaviour with maps.google.com
Go to the maps.google.com website. Enter "56 Jigatanicho, Nishikyo-ku, Kyoto City, kyoto, japan". If you are on the "map" view, you will see your marker centered on a green "park". This is correct.

Incorrect Behaviour with Location+GMaps module using patch5 in #24 of the link given above
Load up a node (or other item) with the address "56 Jigatanicho, Nishikyo-ku, Kyoto City, kyoto, japan". View the map. You will see you are incorrectly placed over 1 mile to the south-east on a building.

Replicated incorrect behaviour in maps.google.com
Go to maps.google.com. Enter "Nishikyo-ku, Kyoto City, kyoto, japan" (we have removed the street and number). This "suburb level" search in maps.google.com gives an identical result to the "incorrect" result from Location with patch.

This leads me to believe Location is potentially only providing Google the suburb level details only, or otherwise GMaps is cripling the results to show suburb level only. Results can get a lot worse: In one regional area test I did, sometimes the "reach" of the area is so large, the marker can be "incorrect" by the equivalent of a 40 minute.

I have tested this with 4 addresses I know of in Japan. Only 1 is obscure. All 4 fail in the same way.

What I don't understand is: how can this happen? Why can't we just expose the entire address string to google and get the correct result? (I'm presuming this is being done). What is going wrong?

I also wonder how many other countries have a similar problem?

Any suggestions for why this may be occuring would be greatly appreciated.

Cheers,
Jason

Comments

jindustry’s picture

jindustry commented

This google faq may provide a clue: http://code.google.com/apis/maps/faq.html#geocoder_differences
I just started using the Location module, but I believe the location module uses the geocoding api when the address is entered to get coordinates. As the faq mentions, this data may differ from maps api. Since a confidence score is also returned, you may be able to see if the confidence geocoding on the Japanese addresses in question is low.

nodecode’s picture

nodecode commented

dealing with this same problem for the United States. Google returns a map maker that is not in the correct location. From my tests, locations with the same postal codes end up with a map maker in the same place regardless of where their address falls within that postal code.

wuihung’s picture

wuihung commented

i have similar problem for Malaysia address too. couldn't able to figure what's wrong. :(

legolasbo’s picture

legolasbo
he/him
Primary language Dutch
Location Middelburg
commented
Status: Active » Closed (outdated)

Closing old D6 issues as D6 is end of life