Geocoding in Thailand

Geocoding is the process of converting addresses into geographic coordinates, which you can use to place markers or position the map. The Google Geocoding API provides a direct way to access a geocoder via an HTTP request. Additionally, the service allows you to perform the converse operation (turning coordinates into addresses); this process is known as "reverse geocoding." We've made a working demonstration on this site, but since Google restricts queries to a limit of 2,500 geolocation requests per day, this page is only available after a login (but not visible for a demo user). Therefore use Google's own example if you want to try out the examples.

Addresses in Thailand

I will try to explain the problem by means of an an example, namely the office address of Thailand Property Gate in Pattaya:
449/84, Moo 12, Thepprasit Road, Nongprue, Banglamung 20150 Chonburi
That's how they write it and that's how western people usually understand and are able to find it. But if you feed Google's geocoder with this, it simply finds – nothing. The correct address (at least for the Google geocoder) would be
Thep Prasit, Na Kluea, Bang Lamung, Chon Buri 20150, Thailand
but the marker position is not correct, it is about 1000 meters further east than the actual office location. The address that positions the marker correct is
Khankheha, Na Kluea, Bang Lamung, Chon Buri 20150, Thailand Hmm, what is wrong? Wrong is the transcription of the Thai letters into the latin alphabet. The address would be written like this in Thai langauge:
449/84 หมู่12 ถนน เทพประสิทธิ์ ตำบลหนองปรือ อำเภอบางละมุง จังหวัดชลบุรี 20150
and, you probably guessed it, the marker is positioned correctly if you feed the geocoder with this address. Google seems to follow the Royal Thai General System of Transcription and this means that there is no Thepprasit Road but rather a Thep Prasit and this road is not in Nongprue but rather in Na Kluea, Bang Lamung (not in Naklua, which again would be wrong, yet a common way of writing it). While it is no problem at all to find the Royal Thai Consulate in Hamburg, Germany, which is at
An der Alster 85, 20099 Hamburg, Germany
you almost always run into problems, if you try to find a Thai address transcribed into latin letters. Actually this is understandable, because no one would search a European address transcribed into Thai letters...

Conclusion

Google is extremely smart and speaks Thai. But it does not understand the rubbish that western people to some extent have made of the Thai words. The Thai alphabet consits of 44 consonants representing 21 distinct consonant sounds plus many vowels, while the latin alphabet has only 23 letters. It stands to reason that when transcribing one alphabet into the other, rules must be observed. If you are not willing to follow these rules, because you fear that your customers would not understand or find Na Kluea instead of Naklua, don't use automatic gecoding.