rasterpic

rasterpic is a tiny package with one single goal: to transform an image into a spatial raster.

Installation

Install rasterpic from CRAN:

install.packages("rasterpic")

You can install the developing version of rasterpic with:

devtools::install_github("dieghernan/rasterpic")

Alternatively, you can install rasterpic using the r-universe:

# Enable this universe
options(repos = c(
  dieghernan = "https://dieghernan.r-universe.dev",
  CRAN = "https://cloud.r-project.org"
))
install.packages("rasterpic")

Example

This package allows you to create cool maps by using a wide variety of objects:

• Spatial object of the sf package: sf, sfc, sfgor bbox.

• Spatial objects of the terra package: SpatRaster, SpatVector, SpatExtent.

• A vector of coordinates with the form c(xmin, ymin, xmax, yman)

An example using a sf object:

library(rasterpic)
library(sf)
library(terra)

# The flag of the United Kingdom
img <- system.file("img/UK_flag.png",
  package = "rasterpic"
)
uk <- st_read(
  system.file("gpkg/UK.gpkg",
    package = "rasterpic"
  ),
  quiet = TRUE
)

# Rasterize!
uk_flag <- rasterpic_img(uk, img)

uk_flag
#> class       : SpatRaster 
#> dimensions  : 400, 800, 3  (nrow, ncol, nlyr)
#> resolution  : 5398.319, 5398.319  (x, y)
#> extent      : -2542183, 1776472, 6430573, 8589900  (xmin, xmax, ymin, ymax)
#> coord. ref. : WGS 84 / Pseudo-Mercator (EPSG:3857) 
#> source(s)   : memory
#> names       : lyr.1, lyr.2, lyr.3 
#> min values  :     0,    13,    34 
#> max values  :   255,   255,   255

# Plot it!

plotRGB(uk_flag)
plot(st_geometry(uk),
  add = TRUE,
  col = adjustcolor("blue",
    alpha.f = 0.5
  )
)

We can also play with other parameters, as well as modifying the alignment of the image with respect to the object:

# Align, crop and mask
uk_flag2 <- rasterpic_img(uk, img, halign = 0.2, crop = TRUE, mask = TRUE)

plot(st_geometry(uk), axes = TRUE)
plotRGB(uk_flag2, add = TRUE)
plot(st_geometry(uk), col = NA, border = "black", add = TRUE)

You can plot the rasters with ggplot2 + tidyterra:

library(ggplot2)
library(tidyterra)

ggplot(uk) +
  geom_spatraster_rgb(data = uk_flag2) +
  geom_sf(fill = NA)

Image formats admitted

rasterpic can parse the following image formats:

• png files.
• jpg/jpeg files.
• tif/tiff files.

Citation

To cite ‘rasterpic’ in publications use:

Hernangomez D (2023). rasterpic: Create a Spatial Raster from Plain Images. https://doi.org/10.5281/zenodo.5910095, https://dieghernan.github.io/rasterpic/

A BibTeX entry for LaTeX users is:

@Manual{R-rasterpic,
  title = {rasterpic: Create a Spatial Raster from Plain Images},
  author = {Diego Hernangómez},
  year = {2023},
  version = {0.2.1},
  doi = {10.5281/zenodo.5910095},
  url = {https://dieghernan.github.io/rasterpic/},
  abstract = {Create a spatial raster, as the ones provided by terra, from regular pictures.},
}

Contribute

Check the GitHub page for source code.