[R-sig-Geo] coercing marmap bathy object to raster spanning the antimeridian

[Fischbach, Anthony]

Projecting a bathymetric dataset spanning the antimeridian as a raster
fails for negative longitudes.

This example is from the marmap vignette.

> aleu <- getNOAA.bathy(165, -145, 50, 65, resolution = 5, antimeridian =
TRUE)
> summary(aleu)
Bathymetric data of class 'bathy', with 599 rows and 180 columns
Latitudinal range: 50.04 to 64.96 (50.04 N to 64.96 N)
Longitudinal range: 165.04 to 214.96 (165.04 E to 145.04 W)
Cell size: 5 minute(s)

Depth statistics:
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
  -7560   -3836    -335   -1832      -7    4374
...
> aleu.r.geo<-marmap::as.raster(aleu)  ## Coerce to a raster
> aleu.r.geo  ## Summary of raster shows that all coordinates longitudes
are positive.
class       : RasterLayer
dimensions  : 180, 599, 107820  (nrow, ncol, ncell)
resolution  : 0.08333333, 0.08287037  (x, y)
extent      : 165.0417, 214.9583, 50.04167, 64.95833  (xmin, xmax, ymin,
ymax)
coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
data source : in memory
names       : layer
values      : -7560, 4374  (min, max)

## Here is my trouble:  I wish to project the rater bathymetry to a local
coordinate system.
> prj.StudyArea <- CRS(" +proj=aeqd +lat_0=55 +lon_0=-170 +x_0=0 +y_0=0
+datum=WGS84 +units=m +no_defs +ellps=WGS84 +towgs84=0,0,0 ")  #Azimuthal
Equadistant -170, 55
> aleu.r<-projectRaster(from=aleu.r.geo, res=20000, crs=prj.StudyArea,
method="bilinear", over=FALSE)
> aleu.r
class       : RasterLayer
dimensions  : 104, 185, 19240  (nrow, ncol, ncell)
resolution  : 20000, 20000  (x, y)
extent      : -1854207, 1845793, -652276.3, 1427724  (xmin, xmax, ymin,
ymax)
coord. ref. : +proj=aeqd +lat_0=55 +lon_0=-170 +x_0=0 +y_0=0 +datum=WGS84
+units=m +no_defs +ellps=WGS84 +towgs84=0,0,0
data source : in memory
names       : layer
values      : -7343.845, 1255.485  (min, max)

The summary of the projected raster (aleu.r) indicates x coordinates
spanning my study area (from negative to positive values in the
prj.StudyArea CRS).
Yet, a plot of the project raster reveals that the eastern half (the region
east of the antimeridian) is missing.
> plot(aleu.r) ## Plot image pasted below.

Is there a trick to getting this right, without introducing missing data at
the antimeridian?
[image: Inline image 1]

Anthony Fischbach, Wildlife Biologist
http://alaska.usgs.gov/science/biology/walrus/
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