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LatLongToMGRSConverter unable to convert near 80 South [antarctica] Invalid UTM or UPS coordinate presented for conversion to MGRS.


alexlynch3450
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As title says, unable to convert lat/long to MGRS when latitude is -80.01 through -81. e.g., x= ‘100’, y= ’-80.1’ . I’m sure this isn’t the exact range but am able to reproduce the error.

Was wondering if someone had additional information on how transformer calculated polar zones and, if there is preprocessing required for points located in south and north polar regions?

Additionally, lmk as comment if you’re able to reproduce error in other FME version

FME Form 2023.2

 

Best answer by liamfez

alexlynch3450 wrote:

@liamfez Thank you for your detailed response! happy fmeing

You’re welcome, sorry I could not be of more help. If nobody else has any ideas you may want to submit a help ticket to safe as it could possible be a bug in the calculation.

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liamfez
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  • July 30, 2024

I am able to reproduce this in FME 2021. I am also seeing it with lat -82.5 but not -83. Changing lon also seems to make a difference as -82.5 works if x=110. Unfortunately I am not very familiar with polar coordinate systems, so I am not exactly sure what is going on.


alexlynch3450
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  • July 30, 2024

@liamfez Thank you for your detailed response! happy fmeing


liamfez
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  • July 30, 2024
alexlynch3450 wrote:

@liamfez Thank you for your detailed response! happy fmeing

You’re welcome, sorry I could not be of more help. If nobody else has any ideas you may want to submit a help ticket to safe as it could possible be a bug in the calculation.


lifalin2016
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  • July 31, 2024

Hi Alex.

As far as I can tell, the UTM projections, on which MGRS is based, are only defined between 80d south and 84d north. So you’re outside the definition area, and unexpected results are to be expected.

Maybe you should use an Antarctic polar projection instead ?

Hope this helps.

Cheers

Lars I.


liamfez
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  • July 31, 2024

@lifalin2016 I thought that as well, but when I looked it up it seems that MGRS switches to universal polar stereographic (UPS) for those regions. And perhaps that is part of the problem. With -81 and -82 being close to where the definitions are switching maybe something is wrong with that conversion?


alexlynch3450
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  • August 5, 2024

submitted and confirmed. . . It’s a bug. 


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