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Datum shift in TBC

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(@rob-omalley-2-2-2-2-2)
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Have a job that was originally done (by others) in SPC, then converted to Ground coordinates and then ultimately truncated. We created a custom projection based on the coords and C.F. provided to us for the area.

Our projection fits the "others" data flawlessly.....but the agency we are working with wants us to use the truncated coordinates for this job.

I've never done it before, but can I create a Datum Shift in TBC (or even Civil 3D) to accommodate this? I would like to just create another project based on the shift so that the crew can work with the other coordinates and I won't have to manually truncate for ACAD work.

What would work the best (not necessarily the easiest) here?

 
Posted : May 20, 2013 8:32 am
(@mightymoe)
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Yes it can be done, in the coordinate system set under local site settings apply the coordinate shift function. That way you can subtract 1000000 from the coordinates-if that's what they want.

looks like this:

When you do it pay attention to the example because a positive sign offset subtracts from the coordinate value. I've never used it so I would test it to be sure it's doing what you want.

 
Posted : May 20, 2013 9:31 am
(@rob-omalley-2-2-2-2-2)
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Tried that and it doesn't work. It throws it out of the coordinate system I'm using so the points vanish during a re-compute.

That was also a TGO window, not a TBC window, wasn't it?...;-)

I don't think it's going to work without creating a custom site vs. a modified coordinate system that I'm currently using.

 
Posted : May 20, 2013 2:14 pm
(@ut-veyor)
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Under the Survey Tab, select Local Site Settings, input the same Grid to Ground factor, and then apply the respective false northings and eastings.

 
Posted : May 20, 2013 2:28 pm
(@mightymoe)
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Yes TGO window. TBC has the same parameters, but I'll admit that I've never used the offset function. Glad to know it has buggs in it. I'd probably just work in the correct corrdinates and then make a spreadsheet that subtracts what they want and send that to them. It's a really old style of surveying to do the subtraction. Used to do that back in the 70's all the time.

 
Posted : May 20, 2013 2:35 pm