Hi Abigail, hi listfolk,
I think the error is saying that it's boundary loop 1, so that should
relate to the first element of your boundary list (i.e.,
survey.area[[1]]) and what you should see is that if you look at the
first and last rows they don't match, so:
all.equal(survey.area[[1]][1,], survey.area[[1]][nrow(survey.area[[1]]),])
should tell you the difference.
One quick fix to this is to just assign
survey.area[[1]] <- rbind(survey.area[[1]],
survey.area[[1]][1,])
but it might be worth checking a bit more thoroughly to see what's going on.
Feel free to e-mail me with your script data if that doesn't help and we
can report back to the list.
cheers,
--dave
On 24/05/2021 21:47, Abigail Schiffmiller wrote:
> Hi all,
>
> I am trying to construct a soap film for a super complex study area
> (Southeast Alaska) for a cetacean line transect survey DSM.
>
> I've encountered some problems with making the soap film and using the
> soap_checker script:
>
> 1. Using the soap_check script I get an error from the boundary loop
> check: “Error in soap_check(bnd = survey.area, tol = 1e-06) :
> Boundary loop(s) 1 don’t have identical start & end points”…I think
> I understand what this means, but I don’t know how to fix it because:
> * I don’t know which loop it is identifying as being open (my
> SpatialPolygonsDataFrame says there is only 1 polygon, but I
> think the ‘loop’ being identified must be one of the holes?)
> * In arcGIS the polygons all seem complete? And I don’t know where
> the ‘start & end points’ are or how I would edit them to be the
> same (in either R or arcGIS).
> 2. following this document:
> (
https://docplayer.net/188653945-Construction-of-a-border-and-internal-knots-for-the-soap-film-smoother.html)
> I can get a map of knots, BUT there are several points where lines
> radiate from which seem to invert the land/ocean and so the knots
> appear on islands instead of water. Maybe these origin points are
> what soap_check is complaining about? But soap_check only identifies
> one 'problem' and there are several of these points?
>
> I'm happy to share my shapefile and script but I'm not having success
> attaching them to this post :/
>
> Any ideas!?!?
> Thanks!!
>
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