GeoMag is an R package to estimate animal geolocation based on triaxis magnetic field measurements, including:
- Magnetic calibration: Correct magnetic distortion using in-situ or in-vitro data.
- Likelihood map estimation: Compute spatial likelihood maps using the World Magnetic Model (WMM), comparing observed and known intensity and inclination.
- Interactive visualization: Explore raw and calibrated data, ellipsoid fits, and 3D scatterplots.
GeoMag is designed to work seamlessly with GeoPressureR, enabling high-resolution migratory track reconstruction using multi-sensor archival tags.
📦 Installation
To install the latest version from GitHub:
# install.packages("pak")
pak::pkg_install("Rafnuss/GeoMag")🛠️ Example Usage
library(GeoMag)
library(GeoPressureR)
withr::with_dir(system.file("extdata", package = "GeoMag"), {
# Create a GeoPressureR tag object (see GeoPressureR documentation)
tag <- tag_create("14DM")
# Label the tag
tag <- tag_label(tag)
})
# Calibrate the tag's magnetic data
tag <- geomag_calib(tag)
# Interactive 3D plot of calibrated magnetic field
plot_mag(tag, type = "acceleration")
plot_mag(tag, type = "magnetic")
plot_mag(tag, type = "calib")
# Compute the spatial likelihood map for each stationary period
tag <- geomag_map(tag)
plot(tag, "map_magnetic")📚 Citation
If you use GeoMag in your research, please cite:
Nussbaumer, R. (2025). GeoMag: Magnetic Field-Based Geolocation in R. https://github.com/Rafnuss/GeoMag
For citation information in R:
citation("GeoMag")