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That’s what made me speculate if there might’ve been a doubling down on a SF somewhere. Should be easy to figure out working with the raw data. Kind of hard to defend your measurements if you can’t replicate them long hand.
WillyIsn’t the mark-to-mark distance a slope distance?
- Posted by: @dave-lindell
Isn’t the mark-to-mark distance a slope distance?
Yep.
Yes, but it’s not a state plane distance. Mark to mark is xyz while state plane is xy, with very different coordinates derived in very different ways.
If you had 5000/5000 coordinates, and you set up your data collector job on a state plane grid, with your 5000/5000 coordinates, you may well get scale factors of that magnitude.
So here’s the update, I went out with another surveyor with a tape and measure the distance between two pk’s set in asphalt both ways and got what i had computed with the dc. (side note to answer one of the previous post we use TSC3 with access). We then measure another shorter distance between two different points with much shorter distance and got what was computed in the dc. I then went out with a different gun and dc and re ran the trav and shot all the same points. The results were identical (.01 =/- human error).
That being said what I figured out was in carlson the way the drawing was setup was with a fixed scale, which was were the error was. We have since redone the drawing to reflect scaling changes.
Thank You to the community for the trouble shooting. This is a great resource.
When I first got my TSC3 all my points were being scale by 1.0007. I finally found that the hold scale factor to 1.0 box was not checked in one of the sub menus. Nobody could ever tell me where it came up with the 1.0007 factor.
Central Montana north-south, that Lambert coordinate system creates big scale factors. And it’s not the elevation, it’s the grid factor that’s huge.
@norman-oklahoma
I set-up the county for a road job, they had purchased chicken buckets from us. They wanted ground distances so I set it up with a grid point near the road project, this was late 90’s. Later some companies I was working with wanted me to set-up a system for them in the same remote location so I gave them the county projection.
About 10 years later they needed some easements in a different state drawn and they had designs for pipelines they gave to me. I looked at the data and it was a mess, they had taken my little projection for their DC’s in the corner of my home county and drove 400 miles west into a different state and used it there, they couldn’t understand why that doesn’t work. “We used the file you gave us.”
Yeah, the scale factors were wild and the bearings were 4 degrees or something.
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