Projection -  First and Second Standard Parallels & False Easting

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05-21-2012 01:50 PM
PremRadhakrishnan
New Contributor III
I am trying to find the first and second standard parallels of Indiana State Plane East projection. I am trying to figure out how to implement some formulas as described in this document "Map Projections - A working Manual  "  p107-109 and examples p295

http://pubs.er.usgs.gov/publication/pp1395


Where do I find this information for a projection system. I cant see this particular piece of information anywhere. I am also looking for the false easting of the central meridian which I am assuming is just the False Easting as defined in the projection.

Below is a link to the spatial reference in question
http://spatialreference.org/ref/esri/102673/ 

Thanks in advance
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MarcinGasior
Regular Contributor
Actually, the State Plane Indiana East is a projected coordinate system which uses Transverse Mercator projection.
This projection doesn't have standard parallels but only False_Easting and False_Northing parameters.

You can check up those parameters eg. by downloading .prj file from the spatialreference.org site you mentioned.
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MelitaKennedy
Esri Notable Contributor
Here's some of the important bits:

    PROJECTION["Transverse_Mercator"],
    PARAMETER["False_Easting",328083.3333333333],
    PARAMETER["False_Northing",820208.3333333333],
    PARAMETER["Central_Meridian",-85.66666666666667],
    PARAMETER["Scale_Factor",0.9999666666666667],
    PARAMETER["Latitude_Of_Origin",37.5],
    UNIT["Foot_US",0.30480060960121924]

One thing to watch out for is that this definition is US survey foot-based. The false easting and northing parameters are also in US survey feet. When you implement the projection, the units are set by the unit of the semimajor axis of the ellipsoid (spheroid) so you'll need to convert it to US feet, or convert the results to US feet before adding the false easting and northing values.

Melita
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