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Get Started

Source: vignettes/rasterpic.qmd

Starting with rasterpic is very easy! You just need an image (png, jpeg/jpg or tif/tiff) and a spatial object from the sf or the terra package to start using it.

Basic usage

Here we use the shape of Austria as an example:

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

# Plot
library(tidyterra)
library(ggplot2)

# Shape and image
x <- read_sf(system.file("gpkg/austria.gpkg", package = "rasterpic"))
img <- system.file("img/vertical.png", package = "rasterpic")

# Create the raster!

default <- rasterpic_img(x, img)

autoplot(default) +
  geom_sf(data = x)
Figure 1: Raster map geolocated with the coordinates of Austria

Options

The function provides several options for expansion, alignment, and cropping.

Expand

With this option, the image is expanded beyond the spatial object:

expand <- rasterpic_img(x, img, expand = 1)

autoplot(expand) +
  geom_sf(data = x)
Figure 2: Example of expansion of image

Alignment

Decide where to align the image:

bottom <- rasterpic_img(x, img, valign = 0)

autoplot(bottom) +
  geom_sf(data = x)
Figure 3: Example of alignment of image

Crop and mask

Create impressive maps:

mask <- rasterpic_img(x, img, crop = TRUE, mask = TRUE)

autoplot(mask)

maskinverse <- rasterpic_img(x, img, crop = TRUE, mask = TRUE, inverse = TRUE)

autoplot(maskinverse)
Figure 4: Example of masked image
Figure 5: Example of inverse masked image

Supported objects for geotagging

  • Spatial objects of the sf package: sf, sfc, sfg or bbox.
  • Spatial objects of the terra package: SpatRaster, SpatVector, SpatExtent.
  • A vector of coordinates with the form c(xmin, ymin, xmax, ymax).

Supported image formats

rasterpic can parse the following image formats:

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