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Star*net Report now includes "Grid" and "Ground" distances. Why?

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 rfc
(@rfc)
Posts: 1901
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I just added another traverse to my control network in Star*net, and printed the whole shebang, and noticed that the second from the last page ("Adjusted Bearings (DMS) and Horizontal Distances (FeetUS)", is now all of a sudden showing both Grid Distances and Ground Distances, as well as Grid Bearings:


Previous reports had only "Bearings" and "Distances". I don't remember changing anything in the Options dialog or anywhere else. I'm not really concerned about Grid right now, but curious about what I might have messed with to produce these results. Any clues?

 
Posted : February 15, 2016 5:37 pm
(@jim-frame)
Posts: 7277
 

Did you change the coordinate system from Local to Grid?

 
Posted : February 15, 2016 8:06 pm
 rfc
(@rfc)
Posts: 1901
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Thanks Jim. That's exactly what happened, although I don't remember making that change. I tried switching it back to local and found a curious thing:

When in "Grid", the distance from say 2-500 shown in the above screen grab is 299.2868' for grid, and 299.3119' for ground.
But when I select "Local" in the preferences, run the adjustment, the distance is shown as 299.3089', a difference of .003'. Why wouldn't it report the same as above (299.3119')?

 
Posted : February 16, 2016 10:52 am
(@scott-zelenak)
Posts: 600
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Ground includes a scale factor and an elevation factor for a combined scale factor.
Local uses 1 as scale factor.

 
Posted : February 16, 2016 11:10 am
(@jim-frame)
Posts: 7277
 

The average geoid separation value may also be playing a role in the difference noted. It's an entry on the same options tab where the type of adjustment is specified.

 
Posted : February 16, 2016 2:29 pm