Get started

Getting started with rasterpic is easy: you need an image file (png, jpeg/jpg or tiff/tif) and a spatial object from the sf, terra or stars packages.

Basic usage

This example uses the shape of Austria:

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

# Load plotting packages.
library(tidyterra)
library(ggplot2)

# Set the spatial object 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 geotagged with the coordinates of Austria

Options

rasterpic_img() provides several options for expansion, alignment, cropping and masking.

Expand

This option expands the raster extent beyond the spatial object:

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

autoplot(expand) +
  geom_sf(data = x)

Alignment

Choose the alignment of the image within the spatial extent:

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

autoplot(bottom) +
  geom_sf(data = x)

Crop and mask

Crop the raster and mask it to the object shape:

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 5: Example of inverse masked image

Supported spatial input classes

rasterpic_img() supports the following input classes:

sf classes: sf, sfc, sfg or bbox.
terra classes: SpatRaster, SpatVector and SpatExtent.
stars classes: stars.
A numeric coordinate vector of the form c(xmin, ymin, xmax, ymax).

rasterpic_img() is an S3 generic. The methods for extent-like inputs use the object extent, and vector methods can also mask the image to the object shape.

Supported image formats

rasterpic can parse the following image formats:

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