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Getting started with rasterpic is straightforward: you need an image file (png, jpeg/jpg or tiff/tif) and a supported spatial input class, such as an object from the sf, terra or stars packages.
Basic usage
This example geotags an image using 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")
# Geotag the image.
default <- rasterpic_img(x, img)
autoplot(default) +
geom_sf(data = x)
Options
rasterpic_img() provides options for expansion, alignment, cropping and masking.
Expand
The expand argument expands the raster extent beyond the spatial object:
expand <- rasterpic_img(x, img, expand = 1)
autoplot(expand) +
geom_sf(data = x)
Alignment
The halign and valign arguments control 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
The crop, mask and inverse arguments control whether the raster is cropped to the object extent and masked 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)
rasterpic_img() supports the following spatial input classes:
- sf classes:
sf, sfc, sfg and bbox.
- terra classes:
SpatRaster, SpatVector and SpatExtent.
- stars class:
stars.
- A numeric coordinate vector of the form
c(xmin, ymin, xmax, ymax).
rasterpic_img() is an S3 generic. Methods for extent-like inputs use the object extent, and vector methods can also mask the image to the object shape.
rasterpic can read the following image formats:
png files.
jpeg/jpg files.
tiff/tif files.
These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
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