Project 1:
Plotting Coordinates and Projections

The above maps are Plate Carree or Geographical Projections and were created with The Interactive Album of Map Projections, referenced below. Plate Carree Projections are both cylindrical, having straight meridians and parallels which intersect at right angles, and equidistant, where distances can be measured accurately along straight lines. "The scale of the projection is accurate on the Equator and all meridians, increasing with distance from the Equator along parallels." (3DSoftware)  The distortion associated with Plate Carree Projections occurs in both shape and area, ellipses widen indicating landmasses are "stretched", increasing with distance from the Equator on parallels.  However, on the Equator there is no distortion (3DSoftware).

The extent of the "main" map is as follows; 55.00° in the North, -60.00° in the East, 20.00° in the South, and -130.00° in the West.  With these geographical coordinates one can see East Greenville, PA, my home town, plotted in the United States of America. In order to show the relative location of East Greenville in Pennsylvania, I "zoomed" in by refining the extents of the map shown in the lower right-hand corner.  The extents are as follows; 42.50° in the North, -74.00° in the East, 39.3° in the South, and -80.75° in the West.

A Geographic Coordinate System is a system which uses a three-dimensional grid or "web" of longitudes and latitudes to determine locations on the Earth's rigid, spherical surface. Longitudes specify positions east and west ranging from +180° (or 180°E) to -180° (or 180°W).  The Prime Meridian, located at 0° longitude, is a commonly known longitude.  Latitudes, or parallels as commonly referred to, specify positions north and south ranging from +90° (or 90°N) to -90° (or 90°S).  The Equator (0° latitude), the North Pole, (90°N), and the South Pole (90°S) are commonly known latitudes. 

A Universal Transverse Mercator (UTM) Grid System is a unique application of the Transverse Mercator Projection, which covers nearly almost the entire Earth's surface. This system is both cylindrical and conformal.  UTM divides the "world" into 60 zones, each stretching 6° of longitude.  Within each zone, coordinates are specified as eastings (distances, in meters, east of origin) and northings (distances north of origin).  UTM is currently utilized by the Army Map Service (University of Florida).

North American Datum of 1927 (NAD27) aligned a coordinate system grid with the Clarke ellipsoid.  In 1983 a different approximation of the Earth's size and shape was accepted, or a change in reference ellipsoids.  The United States now aligned the coordinate system grid with the GRS 80 ellipsoid, referred to as NAD83. However, this caused the geographic coordinate system to shift ten to one hundred meters in regards to control point locations, which required adjustments of those control points (National Geodetic Survey).

State Plane Coordinate System (SPC) is a commonly used plane coordinate system which covers The United States and is divided into 120 zones.  SPC is based on either a Transverse Mercator or Lambert Conic Conformal map projections optimized for each zone. Zones with greater north to south distance are based on Transverse Mercator Projections and zones with greater west to east distances are based on Lambert Conic Conformal (DiBiase). Like UTM, coordinates are specified within each zone as eastings and northings.

The Geographic Coordinate System is a generally broader coordinate system.  It is the only system, of the aforementioned three, which covers the entire surface of the Earth. Universal Transverse Mercator Coordinate Systems cover most of the world, with the exception of latitudes higher than 84°N and 80°S. State Plane Coordinate Systems are limited to the United States, therefore they include the least amount of area.  In addition, their zones are smaller than the UTM.  However, since their zones cover smaller areas the SPC is more accurate than the UTM Coordinate System.  All three systems incorporate the use of longitude and latitude.  Geographic Coordinate Systems use longitude and latitude to locate specific locations while SPC and UTM Systems use them to specify different zone locations.  SPC and UTM Systems share exclusive characteristics. First, they both use "zones", secondly, within these zones, they use eastings and northings to locate individual locations.