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Points being estimated in the Ocean

FLight R Geolocators

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#1 Mendez

Mendez
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Posted 16 May 2017 - 03:35 PM

While using FLightR I am still having a few points fall over the Ocean. I thought that establishing the grid within FLightR and setting the “distance.from.land.to.use=c(-Inf, Inf)” would prevent any points from falling into the Ocean? This is only occurring for a few of the geolocators that I have analyzed although I am still baffled to why this is occurring on the select few.

Any advice on why this is happening and/or how to correct this problem would be greatly appreciated.

Cheers,

Devin



#2 Hendrik

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Posted 16 May 2017 - 04:28 PM

Hi Devin,

 

"inf" stands for infinity, so, as far as I understand it, using  “distance.from.land.to.use=c(-Inf, Inf)” will allow the locations to fall on the ocean. Try :“distance.from.land.to.use=c(-Inf, 0)”.

 

It is all described in detail in the Cran pdf for Flight R. See description from the package below:

 

distance.from.land.allowed.to.use

- define how far from the shoreland animal could occur. Unit - km, negative values are for inland and positive for offshore directions. Inf stays for infinity.

 

Hope that helps!

 

Hendrik



#3 Mendez

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Posted 16 May 2017 - 04:34 PM

Hi Hendrik,

I misspoke earlier when I said I had it   “distance.from.land.to.use=c(-Inf, Inf)” I actually have it set to  “distance.from.land.to.use=c(-Inf, 10)”. When viewing the grid in R it only shows the possible locations over land; however, I am still getting points that fall into the middle of the Gulf of Mexico.

 

Any ideas?

 

~Devin



#4 Hendrik

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Posted 16 May 2017 - 04:46 PM

Hi Devin,

 

are you plotting the "mean" or "median" locations? If I recall right from another post, only the median will stick to the landmask. Try to plot median locations and see whether the problem is fixed. Let me know how it goes :-)

 

Hendrik



#5 Eldar

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Posted 17 May 2017 - 01:08 AM

  Completely agree with Hendrik, and would also suggest plotting these specific twilights separately to see how the probabilities are distributed. Something like:

plot_util_distr(Result, dates=data.frame(as.POSIXct(‘2013-12-01’),
                               as.POSIXct(‘2014-01-31’)),
                               add.scale.bar=TRUE, percentiles=c(0.25, 0.5, 0.75)) 

  Eldar







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