Coordinate Transformation - more

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barryhaupt
Posts: 7
Joined: Fri May 21, 2004 6:47 pm
Location: New Jersey

Coordinate Transformation - more

Post by barryhaupt » Sat May 20, 2006 7:16 pm

Trying out the "coordinate system test dialog" functionality and got an unexpected result.

Tried to convert from Lat Lon to NJ SPC

Input (LL):
Lat 40 44 29.032670N
Lon 74 10 39.881780E

Result (NJ83 - NAD83 New Jersey State Planes, Meter)
x (easting) -25,796,549.10212
y (northing) 33,760,978.24435

Expected result:
x (easting) 177,215.982
y (northing) -211,882.267

What's up?

Glen Cameron
Posts: 1395
Joined: Fri Nov 08, 2002 12:18 pm
Location: Corbeil, Ontario, Canada
Contact:

Post by Glen Cameron » Sun May 21, 2006 8:43 am

If I go to the MsPoints menu -> Geodetic -> Manual Coordinate Conversions - select the datum as you mentioned - and enter in the values you listed, I do get the correct answer.

Latitude was entered as: 40.4429032670
Longtitude was entered as: -74.1039881780

Northing calculated was: 211882.267500295
Easting calculated was: 177215.981783766

Cheers,
Glen W. Cameron, C.E.T.
City of North Bay, Ontario

barryhaupt
Posts: 7
Joined: Fri May 21, 2004 6:47 pm
Location: New Jersey

Coordinate Transformation - more

Post by barryhaupt » Tue May 23, 2006 4:25 pm

Thanks Glen,

Actually, the problem was that I entered the longitude as East instead of West. After I made the correction, the Coordinate System Test Dialog program worked fine.

How would I go about understanding the expected accuracies that are inherent in the various transformations, expecially the transformations from State Plane NAD 27 to State Plane NAD 83? How does this transformation program compare to Corpscon, which as an accuracy of 12 to 18 cm for NAD 27 to NAD 83 State Plane transformations?

Barry

Glen Cameron
Posts: 1395
Joined: Fri Nov 08, 2002 12:18 pm
Location: Corbeil, Ontario, Canada
Contact:

Post by Glen Cameron » Tue May 23, 2006 5:42 pm

We use the Tralaine program under license and to quote from their web-site: http://www.mentorsoftwareinc.com/products/tralaine.htm


NAD27 to NAD83 Conversions

NAD27 to NAD83 conversions (or vice versa) are performed using the exact same algorithm and data files as used by the National Geodetic Service's NADCON program. Tralaine's results are numerically identical to those of NADCON. You can convert directly from NAD27 grid coordinates to NAD83 grid coordinates in one pass through the file. The Canadian National Transformation is fully supported.

Datums

Tralaine's Datum Dictionary contains the definition of 161 datums used around the world. Conversions between datums is accomplished using DMA's multiple regression formulas where data is available, or the Bursa/Wolfe or Molodensky transformations. User's can add new datum definitions using Tralaine's datum editor. Conversions from, for example, NAD27 to WGS72 make full use of the NADCON Overlay if present.



I do not have much else I can quote to answer your question so I hope their web-site will provide what you need.

Cheers,
Glen W. Cameron, C.E.T.
City of North Bay, Ontario

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