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It seems ESRI and QGIS don't have the same definition for my most commonly used projection, NAD83 StatePlane Indiana West (US ft). When I create data in an ESRI product the projection shows up in QGIS as:

USER:100001 - * Generated CRS (+proj=tmerc +lat_0=37.5 +lon_0=-87.08333333333333 +k=0.9999666666666667 +x_0=900000 +y_0=250000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=us-ft +no_defs)

When I create data in QGIS the projection information shows up under the Custom folder as:

NAD83_Indiana_West_ftUS
Authority: Custom

Projection: Transverse_Mercator
false_easting: 2952750.0
false_northing: 820208.333
central_meridian: -87.08333333333333
scale_factor: 0.999966667
latitude_of_origin: 37.5
Linear Unit: Foot_US (0.3048006096012192)

Geographic Coordinate System: GCS_North_American_1983
Angular Unit: Degree (0.0174532925199433)
Prime Meridian: Greenwich (0.0)
Datum: D_North_American_1983
  Spheroid: GRS_1980
    Semimajor Axis: 6378137.0
    Semiminor Axis: 6356752.314140356
    Inverse Flattening: 298.257222101

ESRI's normal entry is:

NAD_1983_StatePlane_Indiana_West_FIPS_1302_Feet
WKID: 2966 Authority: EPSG

Projection: Transverse_Mercator
False_Easting: 2952750.0
False_Northing: 820208.3333333333
Central_Meridian: -87.08333333333333
Scale_Factor: 0.9999666666666667
Latitude_Of_Origin: 37.5
Linear Unit: Foot_US (0.3048006096012192)

Geographic Coordinate System: GCS_North_American_1983
Angular Unit: Degree (0.0174532925199433)
Prime Meridian: Greenwich (0.0)
Datum: D_North_American_1983
  Spheroid: GRS_1980
    Semimajor Axis: 6378137.0
    Semiminor Axis: 6356752.314140356
    Inverse Flattening: 298.257222101

How big of a deal is this? The only difference I can see is in the precision of the scale factors. Is there another difference I missed? Is it worth worrying about?

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Sorry for the title typeo, and thanks for the edit! I don't know what happened to that 'd'. –  HeyOverThere Dec 6 '12 at 16:10
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1 Answer 1

up vote 3 down vote accepted

No, there is nothing wrong about it. Only that Qgis is not sure if EPSG:3535 is wanted. Qgis itself writes the EPSG code at the end of the .prj file, ESRI don't do it.

You can export your file to that CRS, and compare the both with "on-the-fly" disabled.

I get an offset of 0,009 mm. I hope you can live with that ;-)

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I've only used EPSG:2966, and that's the only one I've seen on data from state and/or university sources from around here. Thanks for the offset calc! That puts my mind at ease. –  HeyOverThere Dec 6 '12 at 16:12
    
EPSG:2966, 2968 and 3535 have all identical proj strings. That might be the reason why QGIS is not sure which to take ;-) –  Andre Joost Dec 6 '12 at 16:34
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