Reference

All functions
choose_gcp()	Function to choose the Ground Control Point (GCP) on an image
extract_coords()	Extract coordinates
find_gcp_coords()	Find the coordinates (longitude and latitude) of the ground control points (GCPs) in a given image.
geom_tissot()	Add Tissot's indicatrix to a map
georeference_img()	Georeference an Image using Ground Control Points (GCPs)
suggest_crs()	Suggestions for map projections depending on the extent