O'Reilly logo

Introducing Geographic Information Systems with ArcGIS: A Workbook Approach to Learning GIS, 3rd Edition by Michael D. Kennedy

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Two Projected Coordinate Systems: UTM and State Plane

A coordinate system called Universal Transverse Mercator14 was developed based on a series of 60 projections onto semi-cylinders that contact the Earth along meridians. (To consider, for example, one of these projections, imagine a sheet of paper curved so that it becomes a half cylinder whose radius is that of the Earth’s. Then, with the axis of the cylinder oriented in an east–west direction—hence the term transverse—the paper is brought into contact with a globe along the meridian designating 3° longitude. Then, the surface of the Earth between 0° and 6° is projected onto the paper). This process is repeated for central meridians of 9°, 15°, 21°, and so forth up to 357°. The term “zone” is ambiguously used for this swath of territory. However, UTM projections are further subdivided into areas, also called zones, covering 6° of longitude and, for most zones, 8° of latitude. Further, ArcGIS divides a total zone into a northern and a southern part. In any event, a coordinate system is imposed on the resulting projection such that the numbers in any given zone:

  • Are always positive
  • Always increase from left to right (west to east)
  • Always increase from bottom to top (south to north)

The representation of our previously discussed object (at 38° N and 84.5° W) in the UTM coordinate system, when that system is based on WGS84, is a “northing” of 4,208764.4636 meters and an “easting” of 719,510.3358 meters. The northing is the distance ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required