Oklahoma Statewide Scale Factor
I can’t seem to remember it this morning. Any Okies have this handy. It’s the statewide number they used for all their coordinates. I’m trying to reconcile some points this morning and I think I have some older date and this is the monkey wrench in the mix. Thanks
dp- 11 Replies
I think it’s half of texas’s scale factor……texas being so much bigger and better than any other state…
Found this statement on a DOT form:
“Oklahoma Department of Transportation coordinates were derived by multiplying the Oklahoma Coordinate Systems of 1927 or 1983 by the combined adjustment factor of 1.00010. The ODOT Coordinate System is 2350 feet above sea level.”
PS Survey Division Form (FORM SD #20 )
Be careful!! The scale factor and the combined factor are NOT the same thing. If you enter the combined factor when prompted for the scale factor by the software, you will get a radically different result on your coordinates.
Thanks Jerry. That makes things work much better.
No worries CP. Just using my 11c to check some points.
There is a fellow by the name of Charles Brady over in the City of Ardmore GIS Department that would probably be a good resource for you. He put on a GIS seminar at the recent OK Convention in Midwest City.
Remember to skinnyup those conversions when working in the Panhandle. Full-sized conversions just won’t fit.
Yes, Charles and I are friends and have been for a number of years and have worked together on some GIS programs for URISA, ESRI and the State GIS Council.
Most of Form 11 have geodetic lat/longs so I use those to convert to SPC but couple didn’t have the lat/long and only listed 83 Coordinates. After inverting the factor then we matched within a hundredth on all our common points.
One of the ODOT employees can tell you the reasoning for them adopting a state wide factor instead of computing the actual one for a line. I imagine it was do to the computing power in the field at the time or maybe just for ease within an agency that did work statewide.
They quit using this years ago but every know and then you will find a coordinate still using this factor. I used to know it by heart but it’s been a few years since I needed it. Our references and theirs matched so I knew this had to be the culprit on the coordinate value.
Thanks to all, and especially to Jerry for his quick response. I figured someone would know it on the board and save me having to wait to get ahold of someone from ODOT.
Deral
See my post above Bill. I understand the distortion but it is what they did at the time. And they did great work in our area and some very good traversing and sun shots. We rarely have any problems following anything they did.
dp
> …. they did great work in our area ….
I’m sure, but it’s way past due to update that SD11 form.
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