2

is it possible to use marmap for highly zoomed maps? Here is where I struggle — the resolution from the NOAA grids seem to be insufficient in high resolution...

# Draw a map with getNOAA.bathy

library(marmap)

# sample location
s <- data.frame(y = -44.968276, x = 167.415300)

# map with NOAA 1m data
NOAA.bathy <- getNOAA.bathy(167, 168, -44.5, -45.5, res = 1, keep = TRUE)
plot(NOAA.bathy, image = T, land = F)
points(s$x,s$y, pch = 21, col = "black", bg = "red", cex = 1.3)

Resolution is insufficient to show the marine study area...

As it wasn't possible for me to get a sufficient resolution with getNOAA.bathy(), I tried the GEPCO database (30min) and downloaded a corresponding grid:

# Same location with GEBCO data =
GEPCO.bathy <- readGEBCO.bathy("~/GEBCO_2014_2D_167.0_-45.5_168.0_-44.5.nc")
plot(GEPCO.bathy, image = T, land = F)
points(s$x,s$y, pch = 21, col = "black", bg = "red", cex = 1.3)

A little bit better but not enough to show the sample properly...

This is just a little bit better. However, this is not enough. Here is a comparison to ggmap. 

#comparison to gmaps 
library(ggmap)
gmap = get_map(location = c(lon = s$x, lat = s$y), zoom = 11)
ggmap(gmap) + geom_point(data = s, aes(x = s$x, s$y), color = "red", size = 4)

Could you guys help me to find a way to illustrate my study areas properly with marmap, suitable for publication?

Thank you.

Tony
  • 51
  • 3
  • Perhaps I missed this, but why not use `ggmap` if that works okay? Why do you want to use `marmap`? – Dan Oct 23 '17 at 14:42
  • The study would appear to occur in an estuarine habitat. Why do you need to show bathymetric relief offshore? – ccapizzano Oct 25 '17 at 01:10
  • OK, what do you suggest, I do not necessarily need to show offshore bathymetry. I already tried to extract estuarine bathymetric data from .shp's and .GPKG's to use it with marmap. But that didn't work really well... – Tony Oct 25 '17 at 02:55
  • Yes, unfortunately, `marmap` does not yield high resolution data for many places I've attempted to plot in past projects. The amount of detail in your published map should reflect the journal readership (domestic vs. international) and how much information people will need to follow your methods (e.g., display depth contours, various boundaries). I'd suggested reviewing data from the Land Information New Zealand website, which has a plethora of vector and raster data. I'll pass along some code later as an answer to help. – ccapizzano Oct 25 '17 at 03:32

0 Answers0