Graticule Transform

The graticule transform generates a reference grid for cartographic maps. A graticule is a uniform grid of meridians and parallels for showing projection distortion. The default graticule has meridians and parallels every 10° between ±80° latitude; for the polar regions, there are meridians every 90°.

This transform generates a new data stream containing a single GeoJSON data object for the graticule, which can subsequently be drawn using the geopath or geoshape transform. This transform uses the d3-geo library.

Example

Transform Parameters

Property Type Description
field Field The data field to bin.
extentMajor Array[ ] The major extent of the graticule as a two-element array of coordinates.
extentMinor Array[ ] The minor extent of the graticule as a two-element array of coordinates.
extent Array[ ] Sets both the major and minor extents to the same values.
stepMajor Number[ ] The major step angles of the graticule (default [90, 360]).
stepMinor Number[ ] The minor step angles of the graticule (default [10, 10]).
step Number[ ] Sets both the major and minor step angles to the same values.
precision Number The precision of the graticule in degrees (default 2.5).

Usage

{"type": "graticule", "stepMinor": [15, 15]}

Generates a new graticule data stream with minor parallels and meridians spaced every 15°.