Geographic coordinate systems; GCS (ระบบพิกัดภูมิศาสตร์)
Longitude (ลองติจูด; เสน้ แวง, แกนนอน) value is ±0-180 degree. Begin at Prime Meridian lines (pass
through Greenwich, England) that have 0 degree, connect north pole and south pole as plumb (vertical)
lines.
To the east is + positive and it is represented by “E”
To the west is - negative and it is represented by “W”
Latitude (ละติจูด; เสน้ รุง้ , แกนตั้ง) values are ±0-90 degree. Begin from the Equator which is 0
degree, parallel horizontally with Equator up to north pole and down to south pole.
Go up is + positive and it is represented by “N”
Go down to is - negative and it is represented by “S”