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Vermont SPCS scale factor

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(@gmpls)
Posts: 463
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Good morning everyone. Hopefully there is someone from VT or at least someone familiar with VSPCS scale factors on this board.

I'm working on a project that is in Vermont State Plane CS, NAD 83 and when I calculated a combined scale factor in Trimble TBC, it gave me 1.0000012721. This worries me because in NY most scale factors in my area are 0.9999....

The OPUS data sheets for the 2 points I processed show similar results so I think I'm ok but I'd like to be sure.

Any thoughts?

Gregg

 
Posted : August 13, 2014 5:19 am
(@tim-reed)
Posts: 104
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Combined Scale = Grid Scale * Elevation Scale.

 
Posted : August 13, 2014 7:50 am
(@bill93)
Posts: 9834
 

Download CORPSCON and check against its results.

As mentioned, the factor depends on where you are relative to the SPC zone.

 
Posted : August 13, 2014 7:53 am
(@base9geodesy)
Posts: 240
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Sounds like you're probably working on the western side of the state maybe in Addison County - Scale factors greater than 1 will be very common on the far east and west sizes of any SPC Transverse Mercator zone.

An example from the NGS database:
PG2458; North East Units Scale Factor Converg.
PG2458;SPC VT - 279,253.681 437,334.632 MT 1.00001255 -0 33 44.1
PG2458;SPC VT - 916,184.79 1,434,822.04 sFT 1.00001255 -0 33 44.1

 
Posted : August 13, 2014 12:46 pm
(@thebionicman)
Posts: 4438
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Beware Corps con 6. It has a bug and puts out erroneous factors...

 
Posted : August 13, 2014 5:11 pm