webglobe: Interactive 3D Maps

#webglobe: Interactive 3D Maps

You want to understand your data, but it’s spatially distributed and you’re afraid that trying to make sense of it on something gross, like a Mercator projection, is going to lead you to bad intuitions.

(Greenland is nowhere near that big in reality.)

webglobe can help you do this! It allows you to interactively visualize your data on either a three-dimensional globe or a flat map.

#Example: Earth quakes

library(webglobe)              #Load the library
data(quakes)                   #Load up some data

wg <- webglobe(immediate=TRUE) #Make a webglobe (should open a net browser)
Sys.sleep(10)                     #Wait for browser to start, or it won't work
wg + wgpoints(quakes$lat, quakes$lon, size=5*quakes$mag) #Plot quakes
wg + wgcamcenter(-24, 178.0650, 8000)                    #Move camera

#Example: States

library(webglobe)                 #Load the library
m  <- ggplot2::map_data("state")  #Get data
m$extrude_height <- 1000000*runif(nrow(m),min=0,max=1)
wg <- webglobe(immediate=FALSE)    #Make a webglobe (should open a net browser)
wg <- wg + wgpolygondf(m,fill="blue",alpha=1,stroke=NA)
wg

#Example: dggridR

dggridR is a package for binning spatial data into equally-sized hexagonal or triangular cells. It makes spatial analysis and statistics easier by solving the problem of having to worry about whether your projection is appropriate for the region you are using: all cells have the same area. It also works well with webglobe!

library(dggridR)
library(dplyr)
library(webglobe)
library(colorspace)

#Construct a global grid with cells approximately 1000 miles across
dggs          <- dgconstruct(type="ISEA4T",spacing=1000, metric=FALSE, resround='down')

#Load included test data set
data(dgquakes)

#Get the corresponding grid cells for each earthquake epicenter (lat-long pair)
dgquakes$cell <- dgtransform(dggs,dgquakes$lat,dgquakes$lon)

#Get the number of earthquakes in each cell
quakecounts   <- dgquakes %>% group_by(cell) %>% summarise(count=n())

#Get the grid cell boundaries for cells which had quakes
grid          <- dgcellstogrid(dggs,quakecounts$cell,frame=TRUE,wrapcells=TRUE)

#Update the grid cells' properties to include the number of earthquakes
#in each cell
grid          <- merge(grid,quakecounts,by.x="Name",by.y="cell")

#Make adjustments so the output is more visually interesting
grid$count    <- log(grid$count)
cutoff        <- quantile(grid$count,0.9)
grid          <- grid %>% mutate(count=ifelse(count>cutoff,cutoff,count))

#Generate fill values based on quantiles of number quakes
grid$fill     <- cut(grid$count, breaks=quantile(grid$count, seq(0,1,by=0.2)), labels=heat_hcl(5), include.lowest=TRUE)

#Construct a webglobe
wg            <- webglobe(immediate=FALSE)
wg            <- wg + wgpolygondf(grid, alpha=0.6)
wg

#Modes

webglobes have two modes: immediate and not-immediate. Immediate mode displays a webglobe upon initialization and immediately prints all commands to that globe. Not-immediate mode stores commands and displays them all at once, allowing you to stage visualization without intermediate display. The difference is illustrated below.

Display timing in intermediate mode:

library(webglobe)
data(quakes)                     #Get data
q   <- quakes                    #Alias data
wgi <- webglobe(immediate=TRUE)  #Webglobe is displayed now
Sys.sleep(10)                    #Ensure webglobe runs before continuing
wgi + wgpoints( q$lat,  q$lon)    #Data displays now!
wgi + wgpoints(-q$lat, -q$lon)    #Data displays now!
#Reloading the browser window clears everything

Display timing in not-intermediate mode:

library(webglobe)
data(quakes)                                  #Get data
q   <- quakes                                 #Alias data
wgn <- webglobe(immediate=FALSE)              #Webglobe is not displayed
Sys.sleep(0)                                  #No need to wait
#Note that we have to store commands
wgn <- wgn + wgpoints( q$lat,  q$lon)         #Nothing shown yet
wgn <- wgn + wgpoints(-q$lat, -q$lon)         #Nothing shown yet
wgn <- wgn + wgcamcenter(2.89,-175.962,21460) #Nothing shown yet
wgn                                           #Show it all now!
#Reloading the browser window keeps everything

You can also switch between modes:

library(webglobe)
data(quakes)                                  #Get data
q   <- quakes                                 #Alias data
wgn <- webglobe(immediate=FALSE)              #Webglobe is not displayed
Sys.sleep(0)                                  #No need to wait
#Note that we have to store commands
wgn <- wgn + wgpoints( q$lat,  q$lon)         #Nothing shown yet
wgn <- wgn + wgpoints(-q$lat, -q$lon)         #Nothing shown yet
wgn <- wgn + wgcamcenter(2.89,-175.962,21460) #Nothing shown yet
wgn + wgimmediate()                           #Make it all immediate
wgn
wgn + wgpoints(q$lat, -q$lon)                 #This is shown right away
#Reloading the browser window keeps everything up to `wgimmediate()`

#Roadmap

• Additional graphics primitives

• Submission to CRAN

#Credits

This R package was developed by Richard Barnes (https://rbarnes.org/).

It uses the Cesium WebGL virtual globe and map engine (link).