lonDegToMercX()

function lonDegToMercX(lonDeg): number;

Converts a longitude in degrees into a Web Mercator X coordinate (meters).

Parameters

Parameter	Type	Description
lonDeg	number	Longitude in degrees.

Returns

number

Web Mercator X in meters.

Remarks

Unlike geographic imagery providers, this function does not clamp the longitude range — values outside [-180, 180] are permitted, which is useful for wrapped global grids (e.g. 0…360).

Cesium's Cartographic stores angles in radians, so the input is internally converted using Math.toRadians.