Plotting Airbnb data over NASA's "black marble" geotiff

Question

I am trying to create an image similar to that presented by Ricardo Bion of Airbnb but I would like to plot the visualization over the NASA "black marble" image to give more context as I don't have nearly the data density of the Airbnb dataset.

I downloaded the Nasa black marble image here using the global map 13500x6750 (3km) GeoTIFF 39 MB option.

This issue I keep running into is most of the options and explanations available online have been depreciated in the past few years. I tried using EBImage as shown here but ebimageGrob has been removed from gridExtra. I also tried to use the rasterVis package as shown here but the code breaks at the colorable step.

Here is as far as I have made it trying to layer the tiff behind the plot using the ggplot2 annotation_raster option (this gives the lines between the destinations but only a white background):

library(ggplot2)
library(ggmap)
library(sp)
library(grid)
library(geosphere)
library(plyr)
library(tiff)

# source the theme_map for ggplot2
# source("https://dl.dropboxusercontent.com/u/2364714/theme_map.R")

# in the original post I had a data.frame with 500k rows of top origin destination pairs
trips <- data.frame(origin = c("San Francisco", "Sydney", "Chicago"), 
                destination = c("Paris", "Tokyo", "Boston"), 
                stringsAsFactors = FALSE)


# get lat and lon of cities
trips$geocode_origin <- suppressMessages(geocode(trips$origin))
trips$geocode_destination <- suppressMessages(geocode(trips$destination))


# get intermediate points between the two locations
arch <- gcIntermediate(trips$geocode_origin,
                   trips$geocode_destination,
                   n=100,
                   breakAtDateLine=FALSE, 
                   addStartEnd=TRUE, sp=TRUE)

# http://docs.ggplot2.org/0.9.3.1/fortify.map.html
arch_fortified <- ldply(arch@lines, fortify)

earth <- readTIFF("~/Downloads/dnb_land_ocean_ice.2012.13500x6750_geo.tif")

theme_map <- function(base_size = 12) {
  require(grid)
  theme_grey(base_size) %+replace%
    theme(
      axis.title = element_blank(),
      axis.text = element_blank(),
      panel.grid = element_blank(),
      axis.ticks.length = unit(0,"cm"),
      panel.margin = unit(0,"lines"),
      plot.margin = unit(c(0,0,0,0),"lines"),
      complete = TRUE, 
      panel.background = element_rect(fill = NA, colour=NA)
    )
}

# a few lines of ggplot2 code
ggplot() +
  geom_line(aes(long,lat,group=group), data=arch_fortified, alpha=0.1,size=1, colour="skyblue1") +
  coord_cartesian(ylim =c(-45, 70), xlim=c(-165, 165)) +
  theme_map() +
  geom_point(aes(lon, lat),data=trips$geocode_origin, alpha = 0.8, size = 1, colour = "white") +
  geom_point(aes(lon, lat),data=trips$geocode_destination, alpha = 0.8, size = 1, colour = "white") + 
  annotation_raster(earth, -180, 180, -90, 90)

Thanks!

score 1 · Accepted Answer · answered May 02 '16 at 09:20

I just had to slightly modify your plotting code to get it work:

ggplot(arch_fortified) +
  coord_cartesian(ylim =c(-45, 70), xlim=c(-165, 165)) +
  theme_map() +
  annotation_raster(earth, -180, 180, -90, 90) +
  geom_line(aes(long,lat,group=group), alpha=0.1,size=1, colour="skyblue1") +
  geom_point(aes(lon, lat),data=trips$geocode_origin, alpha = 0.8, size = 1, colour = "white") +
  geom_point(aes(lon, lat),data=trips$geocode_destination, alpha = 0.8, size = 1, colour = "white")

Note that you should first draw the background and only then the lines and points, otherwise the image will cover other plot elements.

Plotting Airbnb data over NASA's "black marble" geotiff

1 Answers1