VHF telemetry error with new update

[Bella Richmond]

Hi all,

I recently used ctmm for one of my master's chapter and it went well, it is a very powerful tool and well documented! I just tried to re-run my analysis with the new ctmm release and am running into some issues.

My data is relocations on radio collars of snowshoe hare using VHF telemetry. I use the package razimuth to get the triangulation location and error ellipses for my data, which I then rename to "COV.x.x", "COV.y.y", and "COV.x.y" so I can incorporate them as error in my akde analysis (as per this discussion in the user group).

Since running my analysis with the update, the error ellipses don't seem to be incorporated (when I plot with error = T I cannot see them and I get a couple other error related messages when going through my script). Does anyone have any suggestions?

I have attached my data and code here. I really appreciate any/all insight.

Thanks so much!

Bella

[Christen Fleming]

Hi Bella,

Sorry, I made some large upgrades to the error modeling and there's now more information now in the telemetry and UERE objects that needs to be set. Here are updated methods for importing triangulated VHF error ellipses:

1. Import the error ellipses in Argos format, where Argos.orientation is the heading of the major axis in long-lat, Argos.semi.major is the sqrt(2)* the standard deviation along the major axis, and Argos.semi.minor is sqrt(2)* the standard deviation along the minor axis. This is probably annoying for you though, as VHF triangulation software works in a projected coordinate system and you would have to do some math to get these values.
   
2. Import your data, set uere(DATA) <- 1 to flag the data as calibrated, delete the bogus variance column with DATA$VAR <- NULL and then copy your covariance columns over.
   
3. Import your data and keep the covariance columns, and then flag the data as calibrated manually with DATA@UERE$UERE[] <- TRUE; DATA@UERE$DOF[] <- Inf; DATA@UERE$N[] <- Inf . In your case, I did
   for(i in 1:length(hares.telem))
   {
     hares.telem[[i]]@UERE$UERE[] <- TRUE
     hares.telem[[i]]@UERE$DOF[] <- Inf
     hares.telem[[i]]@UERE$N[] <- Inf
   }
   after your import and got the error ellipses to plot.
   

I'm sorry this is still annoying to do, as it's really leveraging features that I originally developed and fleshed out for Argos data. I plan to work VHF triangulation into the package at some point, where it will be streamlined and a little better at triangulation than the conventional method, but I need someone to lead that project, as I'm pretty constrained with other tasks.

Best,

Chris

[Bella Richmond]

Hi Chris,

Thanks for the quick response. That makes sense! I will work on figuring out a way to make that work with my VHF data and use ctmm 0.5.10 in the meantime. Thanks for all your hard work, it is very appreciated!

Cheers,

Bella