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Project geographic data using a D3.js projection

Source: R/project.R
project.Rd

Projects spatial data using D3.js geographic projections executed in a V8 JavaScript context. The projection is performed in spherical coordinates, following D3.js design principles, where the Earth is modeled as a sphere rather than an ellipsoid.

Usage

project(
  x,
  proj = "geoAzimuthalEqualArea",
  rotate = NULL,
  reflectX = NULL,
  reflectY = NULL,
  scale = 500,
  center = NULL,
  parallel = NULL,
  parallels = NULL,
  clipExtent = NULL,
  clip = TRUE,
  graticule = c(10, 10),
  additional_layers = FALSE,
  verbose = FALSE,
  ct = .planisphere$ct,
  ...
)

Arguments

x

An sf spatial dataframe to project.

proj

A D3 projection name or constructor (e.g. "geoInterruptedHomolosine").

rotate

Rotation parameters passed to the projection.

reflectX

Logical; whether to reflect the projection on the X axis.

reflectY

Logical; whether to reflect the projection on the Y axis.

scale

Projection scale factor (D3 spherical scale, not planar CRS units).

center

Optional projection center.

parallel

Optional standard parallel of the projection

parallels

Optional standard parallels of the projection

clipExtent

Projection’s viewport clip extent to the specified bounds in pixels

clip

If TRUE, clips the projected geometries to the projected sphere.

graticule

Numeric vector of longitude/latitude step size for graticule generation.

additional_layers

Logical. If TRUE, adds graticule and sphere layers. In this case, the function returns a list. If FALSE (default), it returns a spatial data frame.

verbose

Logical. Display messages

ct

A custom V8 JavaScript context if needed. See new_v8_context().

...

Additional parameters passed to the projection builder.

Value

If additionalLayers = FALSE, a single sf object corresponding to the projected basemap.

If additionalLayers = TRUE, a list of sf objects:

  • basemap: projected input geometries

  • sphere: outline of the projected globe

  • graticule: projected graticule lines

Details

D3 geographic projections are based on spherical geometry. All transformations assume a perfect sphere, which differs from traditional GIS pipelines that often rely on ellipsoidal datums (e.g., WGS84). As a result, this function is primarily intended for visualization and cartographic rendering rather than high-precision geodetic computation.

Examples

library(sf)
world <- st_read(
  system.file("gpkg/land.gpkg", package = "planisphere"),
  quiet = TRUE
)

result <- planisphere::project(x = world, proj = "InterruptedBoggs")