geographiclib

R interface to GeographicLib for precise geodetic calculations on the WGS84 ellipsoid.

Features

Grid Reference Systems

• GARS - Global Area Reference System (military)
• Geohash - Geohash encoding/decoding with precision control
• Georef - World Geographic Reference System (aviation)
• MGRS - Military Grid Reference System encoding/decoding
• OSGB - Ordnance Survey National Grid (Great Britain)

Coordinate Parsing & Formatting

• DMS - Degrees-minutes-seconds parsing and formatting
• GeoCoords - Universal coordinate parsing (MGRS, UTM, DMS, decimal)

Map Projections

• Albers Equal Area - Equal-area conic projection
• Azimuthal Equidistant - Projection centered on any point
• Cassini-Soldner - Historical transverse cylindrical projection
• Gnomonic - Geodesics appear as straight lines
• Lambert Conformal Conic - Configurable LCC projection
• Polar Stereographic - Conformal polar projection with configurable scale
• Transverse Mercator - Custom TM projections with user-defined parameters
• UTM/UPS - Universal Transverse Mercator and Universal Polar Stereographic

Geodesic Calculations

• Geodesic direct/inverse - Distance, bearing, paths on the ellipsoid (exact and fast)
• Geodesic intersections - Find where two geodesics cross
• Nearest neighbor search - Find closest points using geodesic distance
• Polygon area - Accurate area/perimeter on the ellipsoid
• Rhumb lines - Constant-bearing paths (loxodromes)

Coordinate Transformations

• Geocentric - ECEF (Earth-Centered Earth-Fixed) coordinates
• Local Cartesian - East-North-Up (ENU) local coordinates

Ellipsoid

• Ellipsoid parameters - WGS84 parameters, curvature, auxiliary latitudes

All functions are fully vectorized with rich metadata output.

Installation

remotes::install_github("hypertidy/geographiclib")

Quick example

library(geographiclib)

# Coordinates to MGRS
pts <- cbind(lon = c(147.32, -74.01, 0.13),
             lat = c(-42.88, 40.71, 51.51))
(codes <- mgrs_fwd(pts))
#> [1] "55GEN2613352461" "18TWL8362507036" "31UCT0084710446"

# MGRS back to coordinates with full metadata
mgrs_rev(codes)
#>           lon    lat        x       y zone northp precision convergence
#> 1 147.3200014 -42.88 526133.5 5252462   55  FALSE         5  -0.2177510
#> 2 -74.0099941  40.71 583625.5 4507036   18   TRUE         5   0.6457496
#> 3   0.1299966  51.51 300847.5 5710446   31   TRUE         5  -2.2471333
#>       scale grid_zone square_100km        crs
#> 1 0.9996084       55G           EN EPSG:32755
#> 2 0.9996861       18T           WL EPSG:32618
#> 3 1.0000870       31U           CT EPSG:32631

## arguments are vectorized
rev0 <- mgrs_rev(vcodes <- mgrs_fwd(rbind(pts, pts), precision = c(0L, 1L, 2L, 3L, 4L, 5L)))
cbind(mgrs = vcodes, rev0)
#>              mgrs         lon       lat        x       y zone northp precision
#> 1           55GEN 147.6124506 -42.90097 550000.0 5250000   55  FALSE         0
#> 2         18TWL80 -73.9940004  40.69152 585000.0 4505000   18   TRUE         1
#> 3       31UCT0010   0.1249653  51.51035 300500.0 5710500   31   TRUE         2
#> 4     55GEN261524 147.3202040 -42.88010 526150.0 5252450   55  FALSE         3
#> 5   18TWL83620703 -74.0100003  40.70999 583625.0 4507035   18   TRUE         4
#> 6 31UCT0084710446   0.1299966  51.51000 300847.5 5710446   31   TRUE         5
#>   convergence     scale grid_zone square_100km        crs
#> 1  -0.4169241 0.9996308       55G           EN EPSG:32755
#> 2   0.6559370 0.9996889       18T           WL EPSG:32618
#> 3  -2.2510864 1.0000887       31U           CT EPSG:32631
#> 4  -0.2178893 0.9996084       55G           EN EPSG:32755
#> 5   0.6457454 0.9996861       18T           WL EPSG:32618
#> 6  -2.2471333 1.0000870       31U           CT EPSG:32631

Documentation

Function reference and vignettes are available at https://hypertidy.github.io/geographiclib/

Articles:

• Getting Started - Package overview and quick examples
• Geodesics - Distance, bearings, waypoints, intersections, rhumb lines, polygon area, nearest neighbors
• Grid References - MGRS, Geohash, GARS, Georef, GeoCoords, DMS formatting
• Projections - UTM/UPS, Transverse Mercator, Lambert, Albers, Polar Stereographic, and more
• Local Coordinates - Geocentric (ECEF), Local Cartesian (ENU), ellipsoid properties

Performance

Fast C++ implementation - process tens of thousands of coordinates in milliseconds:

x <- do.call(cbind, maps::world.cities[c("long", "lat")])
system.time(mgrs_fwd(x))       # 43,645 points
#>  user  system elapsed 
#>  0.04    0.00    0.04

Code of Conduct

Please note that the geographiclib project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.