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project settings

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The GPS project settings are WGS 1984 UTM 38N
What if my project is located between two zones
38N, 39N  .


Another question what if I work between the  38R and 38S on (UTM projection), which affects the measurement accuracy  When we work on GPS  ?


Posted : October 31, 2022 9:42 am
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I was in 38/39 while in Kuwait.

Where the majority of the work is and elevations change a lot make that the home for the project.

You'll have to use the AUS/Pos and Canadian positioning for best accuracy for final deliverables. 

Local datums wo be the final tweaks for the win.

Posted : October 31, 2022 10:26 am
John Putnam
Posts: 1900
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The choice of UTM zones will not affect the accuracy of your GNSS per say, just the amplitude of the resulting scale factor and convergence angle at any given point.  I can apply UTM zone 1N and 39S to the any set of geodetic coordinates.  The resulting grid distances for each will be just as accurate while the ratio to the same distance measured on the ground will be wildly different.

If your project truly is one the line between two zones, and you are not bound by jurisdictional requirements, your best bet is to calculate the combined scale factor for a scattering of points in the area of interest and then chose the zone that is closest to 1.000000000 for those points.  Terrain can have a large effect on the amount of distortion in any given area.

If the project is large enough or you do a substantial amount of work in the area then your best bet may be to develop a low distortion projection for the area.

Posted : November 1, 2022 6:57 am
OleManRiver, Jitterboogie, AQASYASIN and 1 people reacted

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You can easily check what john said. Just do any adjustments and all at lat long ht then project the geographic coords lat long ht to tge two different zones and projections independent of each other. Then you can solve for combined factors in each to see how many PPM’s are going on in each. Which should help you decide which one or the LDP option. Another great thing about lat longs heights is you can do anything with them as long as you know which datum and project them 6 ways to Sunday and twice on Monday. To get what you want or need. 

Posted : November 3, 2022 6:22 pm