Thursday, January 28, 2010

New Muban in Sakon Nakhon

Already on January 19, a new administrative village (Muban) in Sakon Nakhon was announced (Gazette). The northern part of village 2 Ban Ngon (บ้านง่อน), Sawang Daen Din subdistrict, Sawang Daen Din district was split off and forms the new village 26 named Ban Ngon Mai (บ้านง่อนใหม่).

Sadly the TAO website has no map of the village boundaries, but what is funny is the map found in the PDF to show the location of the subdistrict - the coloring is the same as in the Wikipedia tambon maps I created, only I never did any for the northeast.

But I have now programmed the conversion of the coordinates as they are given in these announcements. These are written in the MGRS scheme, a different way to write UTM coordinates. To further complicate it, the first three characters - zone number and zone band - are omitted, as these can be deduced directly from the fact that it is a coordinate in Thailand. The conversion was a bit tricky, and I am not fully sure which datum I have to use as with neither WGS84 nor the Thai Indian 1975 they exactly fit a landmark in Google Earth, which however could also be due to a minor misalignment of the satellite images there - I believe the southernmost point should be on highway 22, so I have it all moved up to 500 m to the east. As I did not parse the boundary descriptions but only the explicit coordinates, the map below gives only an idea of the outline of the new village 26 (blue) and the remaining village 2 (red).

View Muban 26, Sawan Din Daeng in a larger map

Update: as you notice in the map, the points now fit the landmarks - I found the error in my datum conversion code.

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