Map Projections
For ICON Engineering
State Plane Coordinate System
- Utilizes Lambert Conformal Conic projection
- Two standard parallels where cone intersects sphere
- Scale decreases between parallels, increases outside
Lambert Conformal Conic
Conformal projection
- Angles are preserved
Conic projection
- Scale (distance) preserved at the standard parallels
Colorado State Plane Central
PROJCS["NAD_1983_HARN_StatePlane_Colorado_Central_FIPS_0502_Feet",
GEOGCS["GCS_North_American_1983_HARN",
DATUM["D_North_American_1983_HARN",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic"],
PARAMETER["False_Easting",3000000.000316083],
PARAMETER["False_Northing",999999.999996],
PARAMETER["Central_Meridian",-105.5],
PARAMETER["Standard_Parallel_1",38.45],
PARAMETER["Standard_Parallel_2",39.75],
PARAMETER["Latitude_Of_Origin",37.83333333333334],
UNIT["Foot_US",0.3048006096012192]]Components of the .prj file:
Name and Geoid data
Parameters unique to Colorado State Plane Central
Coordinates
Projecting vs Defining Projection
Projecting data is mathematically changing coordinates from one projection to another
Defining a projection is letting the GIS know which projection the data is in currently
If coordinate system is unknown, it must be defined. You can determine which projection it is in by checking its feature extents in ArcCatalog
Standard Projections Used at ICON
NAD83 HARN/Colorado State Plane North (us feet): EPSG 2876
NAD83 HARN/Colorado State Plane Central (us feet): EPSG 2877
NAD83 HARN/Colorado State Plane South (us feet): EPSG 2878
NAD83/UTM Zone 13 North: EPSG 26913
QUESTIONS?
Map Projections
By Eben Dennis
