During the 1930s, the U.S. Coast and Geodetic Survey (USC&GS),
now NGS developed the State Plane Coordinate System which have been very
popular at the local level. Many users find State Plan coordinates more
adaptable than UTMs because the zone boundaries fall along political lines
(e.g., State and County) as opposed to geometric lines. In addition,
State Plane scale distortions are generally smaller, allowing more accurate
distance computations when scale factor adjustments are omitted.
Standards for The State Plane Coordinate System of 1983 can be found at:
http://www.ngs.noaa.gov/PUBS_LIB/ManualNOSNGS5.pdf
(3.6
MB)
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The following procedure allows Magellan M-3xx, SporTrak, Meridian, and eXplorist series receiver GPS User Grids to display State Plane meter and survey feet coordinates directly:
State Plane point-of-origin data is difficult to find and takes considerable searching of the internet! However, Peter H. Dana, Ph. D., Department of Geography - University of Texas at Austin, pointed me to http://gpsinformation.net/mapinfow.prj -which has comma-separated-values data for all the State Planes in the US. About 20% of this file was used to create a spread sheet: http://gpsinformation.net/mapinfow-e.xls. For a summary of the spread sheet, see this TEXT.
NOTE: This Excel file is needed to obtain the data to enter into the GPS unit; however, it requires that you know which zone and whether the data you need is in the NAD-27 or NAD-83 datum beforehand. State Plane zones can be determined from: http://home.comcast.net/~rickking04/gis/spc.htm
For Data Supplied in Meters
Example from the Georgia data:
Georgia West Zone 1002 (Includes Atlanta)
Latitude of Origin = 30° 00' 00"
Longitude of Origin and Central Meridian = 84° 10' 00"
Datum = NAD-83
Scale = 0.9999
False Easting at Origin = 700,000 meters
False Northing at Origin = 0 meters
Settings for the Magellan User Grid using the new NAD-83 SPCS :
NOTE: Magellans will read out
grid coordinates in the form: "123-45-678E" -which would be 12,345,678E
To set up the NAD83 Georgia West zone in a Magellan, go to:
SETUP then MAP DATUM and enter NAD83
Exit SETUP, then enter and save waypoint 34° 50'N 85° 30'W
(A corner of the state was picked to get well away from the origin
and bring out any errors.)
Enter SETUP, COORD SYSTEM, PRIMARY, USER GRID and enter the parameters:
PROJECTION: TRANS MERC
LATITUDE OF ORIGIN: 30.00000N
LONGITUDE OF ORIGIN: 84.16667W
SCALE FACTOR: 0.99990000
UNITS TO METERS CONV.: 1.00000000
FALSE EAST AT ORIGIN: 700000.0 (meters)
FALSE NORTH AT ORIGIN: 0.0
The program CORPSCON by the U.S. Army Corps of Engineers will
allow you to transform easily between NAD 27 and NAD 83 in any of
the coordinate values you would like to use (e.g., State Plane, UTM or
Lat/Long). This public domain software will perform conversions
for individual points, and is available from: http://crunch.tec.army.mil/software/corpscon/corpscon.html
Another conversion site is Earth
Point.
Now convert lat/lon 34° 50'N 85° 30'W to state plane.
Compare Magellan and National Geodetic Survey online converter results:
east north
Magellan
578045 m 536747 m
NGS program
578044.5 m 536746.7 m
It's true the Magellans won't allow a negative number for false northing (as needed by the Garmins), but one isn't needed. That's just a kluge necessary to compensate for their limited user grids. (There's one exception we'll mention later.)
Also, the Magellans will display/accept coordinates in meters,
survey feet, international feet, cubits, whatever unit you want. Just enter
the appropriate UNITS TO METERS CONV. factor in the user grid setup (and
also enter easting and northing in the same units).
They can even do the oblique Mercator grid of Alaska Zone
1, and with consistent accuracy, as confirmed using NGS software. However,
inability to set a negative false northing is a factor here, as -5 million
meters is required. The workaround is to ignore the spurious leading 5
on northing when reading coordinates, and insert one when inputting. There
is no other state plane zones (NAD27 or NAD83) with negative false northings,
so this is a minor problem.
For Data Supplied in Survey Feet
IMPORTANT NOTE: The "Foot" specified for NAD 27 and NAD-83 are what are commonly called "U.S. Survey Foot," which is related to the meter by 1 m = 3.280833333333.... ft. This is important, as you will often find the conversion listed in many sources as 1 m = 3.280839895 ft, which is referred to as the International Foot, adopted by the U.S. Bureau of Standards in 1959. Ignorance of these differences can easily distort your conversions by 10-15 ft!
In the case of the Magellan's User Grid Coordinate System, the UNITS TO METERS CONV. must be in survey-feet/meter -or 0.30480061. The last third of http://gpsinformation.net/mapinfow-e.xls supplies points of origin in Survey Feet for NAD-83. Thus copying from that part of the table, the Magellans can read coordinates in Survey Feet by altering the above procedure as follows:
Example from the Georgia data:
Georgia West Zone 1002 (Includes Atlanta)
Latitude of Origin = 30° 00' 00"
Longitude of Origin and Central Meridian = 84° 10' 00"
Datum = NAD-83
Scale = 0.9999
False Easting at Origin = 2,296,583 feet
False Northing at Origin = 0 feet
Settings for the Magellan User Grid using the new NAD-83 SPCS :
NOTE: Magellans will read out
grid coordinates in the form: "123-45-678E" -which would be 12,345,678E
To set up the NAD83 Georgia West zone in a Magellan, go to:
SETUP then MAP DATUM and enter NAD83
Enter SETUP, COORD SYSTEM, PRIMARY, USER GRID and enter the parameters:
PROJECTION: TRANS MERC
LATITUDE OF ORIGIN: 30.00000N
LONGITUDE OF ORIGIN: 84.16667W
SCALE FACTOR: 0.99990000
UNITS TO METERS CONV.: 0.30480061 (survey-feet/meter)
FALSE EAST AT ORIGIN: 2296583 (survey feet)
FALSE NORTH AT ORIGIN: 0.0
Example of Lambert Conformal Conic State Plane Parameters
NOTE: About half the SPCS zones in the US use Lambert Projections. Magellan handles them easily.
Tennessee Zone 4100, NAD-83 (LCC Projection)
Latitude of Origin = 34° 20' 00" N
Longitude of Origin and Central Meridian = 86° 00' 00" W
North Standard Parallel = 36° 25' 00" N
South Standard Parallel = 35° 15' 00" N
False Easting at Origin = 600,000 meters
False Northing at Origin = 0 meters
Older TN State Plane Parameters (Note significant differences)
Tennessee Zone 4100, NAD-27 (LCC Projection)
Latitude of Origin = 34° 40' 00" N
Longitude of Origin and Central Meridian = 86° 00' 00" W
North Standard Parallel = 36° 25' 00" N
South Standard Parallel = 35° 15' 00" N
False Easting at Origin = 2,000,000 survey feet
False Northing at Origin = 100,000 survey feet
Settings for Magellan User Grid involving the NAD-27 LCC projection and display in survey feet:
To set up the NAD27 Tennessee Zone in a Magellan, go to:
SETUP then MAP DATUM and enter NAD27
SETUP, COORD SYSTEM, PRIMARY, USER GRID and enter the parameters:
PROJECTION: LAMBERT CON (conformal conic)
2 STANDARD PAR (Parallels)
LATITUDE OF ORIGIN: 34.66667N
LONGITUDE OF ORIGIN: 86.00000W
PARALLEL 1: (This is the northern parallel) 36.41667N
PARALLEL 2: (This is the southern parallel) 35.25000N
SCALE FACTOR: 1.00000000
UNITS TO METERS CONV: 0.30480061 (survey-feet/meter)
FALSE EAST AT ORIGIN: 2,000,000 (survey feet)
FALSE NORTH AT ORIGIN: 100,000 (survey feet)
The program CORPSCON by the U.S. Army Corps of Engineers will allow you to transform easily between NAD 27 and NAD 83 in any of the coordinate values you would like to use (e.g., State Plane, UTM or Lat/Long). This public domain software will perform conversions for individual points, and is available from: http://crunch.tec.army.mil/software/corpscon/corpscon.html
Using CORPSCON on a test point located at 36° 00'N, 83° 45'W (the NE corner of a DRG map for verification):
east north
Magellan
2,665,503' 592,970'
NGS program 2,665,502.7'
592,971.8'
Addendum: Instructions to handle the 'one-of-a-kind', Alaska Zone 1
In SETUP, do COORD SYSTEM, PRIMARY, LAT/LON, DEG/MIN (either one).
Still in SETUP, do MAP DATUM, PRIMARY, NAD83.
Exit SETUP, then enter and save waypoint 59 30' N 139 40' W.
Return to SETUP, do COORD SYSTEM, PRIMARY, USER GRID.
PROJECTION: OBLQ MERC
POINT AZ. (this toggles between POINT AZ. and TWO POINT)
LATITUDE OF CENTRAL PNT.: 57.0000N
LONGITUDE OF CENTRAL PNT.: 133.66667W
AZIMUTH OF CENTRAL LINE: 323.13010 (360° less -36.86989765°)
SCALE FACTOR: .99990000
UNITS TO METERS CONV.: 1.00000000
FALSE EAST AT ORIGIN: 05000000.0 (meters)
FALSE NORTH AT ORIGIN: 00000000.0
Read back the waypoint. The Magellan values vs. NGS software:
east north
Magellan
479251 m 5868655 m
NGS program 479251.1 m
868655.1 m
To get a better understanding of some of the geodetic principles involved, see "Geodesy for the Layman" http://www.ngs.noaa.gov/PUBS_LIB/GeoLay.pdf