[R-sig-Geo] 3rd+ rasters added using "plot(r, add=TRUE)" are misregistered

[Michael Sumner]

I just wonder if this is related to an existing resize problem when
overplotting? I see this on the windows() graphics device, you need to
try these two sets of plot commands and resize the window (especially
stretch it in one direction) to see the problem at ## 1 and ## 2

v <- list(x = seq(0, 1, length = nrow(volcano)), y = seq(0, 1, length
= ncol(volcano)), z = volcano)
cl <- contourLines(v, levels = 160)[[2]]

image(v, xaxs = "i")
lines(cl)
## (1) now resize the window, it's all good - the contour stays in the
## right place


## however, resize after adding the lines to a raster plot
## and the relationship is broken
library(raster)

plot(raster(v), xaxs = "i")

lines(cl)

## (2)

May be totally unrelated but I thought it worth pointing out. It's
hard to trace through the setting up that raster's plot does (well, I
find it hard to do - I've tried a few times to figure out where these
problems are happening).

Cheers, Mike.

On Wed, Dec 4, 2013 at 5:57 AM, Josh O'Brien <joshmobrien at gmail.com> wrote:
> Hi all,
>
> Briefly, running the following code will not produce a single grey ring, as
> would be expected. The first three raster layers all stack up neatly, but
> the 4th and subsequent raster layers are all shifted/skewed to the right.
>
> It appears that the plotting engine loses track of the fact that some space
> in the original plot was allocated to a legend, and just begins plotting as
> if a wider canvas were available to it.
>
> I'm not sure whether this is ultimately an issue with raster or sp or
> something else, which is why I'm noting it here on R-sig-geo. (I'm also
> fully aware that there are other and better ways to add several raster
> layers to a plot, but still think the following behavior qualifies as a bug
> that I ought to report.)
>
>   library(maptools) ## Only needs to be installed for example data
>   library(raster)
>   library(rgeos)
>
>   ## Create an example raster
>   p <- shapefile(system.file("shapes/co37_d90.shp", package="maptools"))
>   p <- p[31,]  ## A tall narrow county polygon
>   pr <- gDifference(gBuffer(p, width=.01), p)
>   r <- rasterize(pr, raster(extent(pr), ncol=100, nrow=100))
>
>   ## These three are properly registered on one another
>   plot(r, col="yellow", legend=FALSE)
>   plot(r, col="green", legend=FALSE, add=TRUE)
>   plot(r, col="grey", legend=FALSE, add=TRUE)
>   ## All subsequent "layers" are improperly shifted/skewed to right
>   plot(r, col="yellow", legend=FALSE, add=TRUE)
>   plot(r, col="blue", legend=FALSE, add=TRUE)
>   plot(r, col="red", legend=FALSE, add=TRUE)
>   plot(r, col="grey20", legend=FALSE, add=TRUE)
>   ## Following the above, SpatialPolygons are also shifted/skewed
>   plot(p)
>
>
>
> My session info, in case it matters, is:
>
>> sessionInfo()
> R version 3.0.2 (2013-09-25)
> Platform: i386-w64-mingw32/i386 (32-bit)
>
> locale:
> [1] LC_COLLATE=English_United States.1252
> [2] LC_CTYPE=English_United States.1252
> [3] LC_MONETARY=English_United States.1252
> [4] LC_NUMERIC=C
> [5] LC_TIME=English_United States.1252
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] rgdal_0.8-14  rgeos_0.3-2   raster_2.1-66 sp_1.0-14
>
> loaded via a namespace (and not attached):
> [1] compiler_3.0.2  grid_3.0.2      lattice_0.20-24 tools_3.0.2
>
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>
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-- 
Michael Sumner
Hobart, Australia
e-mail: mdsumner at gmail.com