projection.scale([scale]) If scale is specified, sets the projection’s scale factor to the specified value and returns the projection. If scale is not specified, returns the current scale factor; the default scale is projection-specific. The scale factor corresponds linearly to the distance between projected points; however, absolute scale factors are not equivalent across projections.

projection.precision([precision]) If precision is specified, sets the threshold for the projection’s adaptive resampling to the specified value in pixels and returns the projection. This value corresponds to the Douglas–Peucker distance. If precision is not specified, returns the projection’s current resampling precision which defaults to √0.5 ≅ 0.70710…

projection.fitSize(size, object) A convenience method for projection.fitExtent where the top-left corner of the extent is [0, 0]. The following two statements are equivalent: projection.fitExtent([[0, 0], [width, height]], object); projection.fitSize([width, height], object);

projection.clipExtent([extent]) If extent is specified, sets the projection’s viewport clip extent to the specified bounds in pixels and returns the projection. The extent bounds are specified as an array [[x₀, y₀], [x₁, y₁]], where x₀ is the left-side of the viewport, y₀ is the top, x₁ is the right and y₁ is the bottom. If extent is null, no viewport clipping is performed. If extent is not specified, returns the current viewport clip extent which defaults to null. Viewport clipping is indep

projection.fitExtent(extent, object) Sets the projection’s scale and translate to fit the specified GeoJSON object in the center of the given extent. The extent is specified as an array [[x₀, y₀], [x₁, y₁]], where x₀ is the left side of the bounding box, y₀ is the top, x₁ is the right and y₁ is the bottom. Returns the projection. For example, to scale and translate the New Jersey State Plane projection to fit a GeoJSON object nj in the center of a 960×500 bounding box with 20 pixels of paddi

project.invert(x, y) The inverse of project.

project(lambda, phi) Projects the specified point [lambda, phi] in radians, returning a new point [x, y] in unitless coordinates.

projection.clipAngle([angle]) If angle is specified, sets the projection’s clipping circle radius to the specified angle in degrees and returns the projection. If angle is null, switches to antimeridian cutting rather than small-circle clipping. If angle is not specified, returns the current clip angle which defaults to null. Small-circle clipping is independent of viewport clipping via projection.clipExtent.

projection(point) Returns a new array [x, y] (typically in pixels) representing the projected point of the given point. The point must be specified as a two-element array [longitude, latitude] in degrees. May return null if the specified point has no defined projected position, such as when the point is outside the clipping bounds of the projection.

projection.center([center]) If center is specified, sets the projection’s center to the specified center, a two-element array of longitude and latitude in degrees and returns the projection. If center is not specified, returns the current center, which defaults to ⟨0°,0°⟩.