Types of coordinate systems:
The following are 2 common types of coordinate systems used in a GIS
1) Geographic coordinate systems; GCS (ระบบพิกัดภูมิศาสตร์) is the system using 3D
spherical surface to define locations on the Earth surface.
A point is referenced by its Longitude (ลองติจูด; เสน้ แวง, แกนนอน) and Latitude (ละติจูด; เสน้ รุง้ ,
แกนตั้ง) values.
Longitude and Latitude are angles measured from the earth’s center to a point on the
earth’s surface. The angles are often measured in degrees, minute and second.
2) Grid or Projected coordinate systems; PCS (ระบบพิกัดกริด) is defined on a flat, 2D
surface (such as Universal Transverse Mercator (UTM), this is the perpendicular coordinate
system that comes from the crossing of 2 parallel straight-lines system and equal distance
between 2 parallel straight lines .
Unit of distance is meter in metric system.