problem in EBS UTM conversion?

[DanOvando]

Attempting to merge location of estimated knots with other databases, and noticed that the locations produced by Convert_LL_to_UTM_Fn for some regions appear to be off. Specifically, running the VAST--single-species-example.Rmd for the EBSBTS data, calling Convert_LL_to_UTM_Fn and by extension PBSmapping::convUL results in convUL guessing that the data are in UTM zone 32, which runs over central Africa.

Setting flip_around_dateline to FALSE in Prepare_EBS_Extrapolation_Data_Fn.r seems to solve the problem, as convUL now assigns a mean UTM zone of 2, and the eastings and northings now look more or less right, though they still don't perfectly match values produced by conversion from lat/lons by rgdal::project. Any thoughts? Bug in flip_around_dateline conversion? Or am I just missing something?

[James-Thorson]

I don't know anything about rgdal::project, maybe that deals more naturally with dateline projection issues?

But yes, Extrapolation_List keeps track of the UTM-zone and whether it was flipped around the dateline, and then this is used in other functions to that it is consistent internally. probably a better way to do this ;)

[DanOvando]

Ah, so this is a hack to deal with the dateline in other spots in the code? i.e. if other functions see flip_round_dateline = T and zone = 32, they convert that spot to a place in the EBS, even though if you technically try and map those eastings and northings directly you'll get a spot off the west coast of Africa?

[James-Thorson]

correct.

[DanOvando]

got it, thanks! I may submit some changes to track the "true" lat-long of the knots as well just for clarity if you want

[James-Thorson]

sure thing, I'm getting better at pull-request management if you want to do it that way. but please use a clean branch, I don't know how to sort through different potential sections of a pull-request.

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