overlap() error : Inconsistent projections

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Devin Fitzpatrick

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Jul 15, 2021, 6:24:44 PM7/15/21
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Hi there,

I am trying to use overlap() for the first time and having some trouble, repeatedly getting this error: Error in check.projections(object) : Inconsistent projections. 

For example when trying to compare the overlap of 2 squirrels I created a list of their two ctmm fit objects obtained from ctmm.select()


> squirrels <- list(M.IID.09, M.IID.24)

> overlap(squirrels, level = 0.95, debias = TRUE)

Error in check.projections(object) : Inconsistent projections.

>


Same error when I try with the UDs obtained from akde() 


> squirrels <- list(KDE.09, KDE.24)

> overlap(squirrels, level = 0.95, debias = TRUE)

Error in check.projections(object) : Inconsistent projections.


I’m not sure why as the data for both squirrels is in the same coordinate system/format/etc. 

Any guidance would be much appreciated!

Thank you,

Devin 

Christen Fleming

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Jul 16, 2021, 1:51:14 AM7/16/21
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Hi Devin,

If you imported the squirrels separately and did not manually specify a projection, then they probably ended up with different automated projections. But this is easy to fix, by assigning them the same projection before fitting the models: https://ctmm-initiative.github.io/ctmm/reference/projection.html

SQUIRRELS <- list(SQUIRREL1, SQUIRREL2)
projection(SQUIRRELS) <- median(SQUIRRELS)

and then working with from the re-projected SQUIRRELS list.

Also, depending on how you tracked them, you might want to check and see if the location error needs to be modeled: https://ctmm-initiative.github.io/ctmm/articles/error.html

Best,
Chris

Devin Fitzpatrick

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Jul 17, 2021, 3:21:28 PM7/17/21
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Hi Chris,

I had imported the squirrels separately and that fixed the issue, thank you very much! The squirrels were tracked using GPS collars. 

Best,
Devin 

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