cheap-ruler

A collection of fast approximations to common geographic measurements, along with some utility functions. Useful for speeding up analysis scripts when measuring things on a city scale by replacing expensive Turf calls in key places.

Usage

var ruler = cheapRuler(35.05, 'miles');
var distance = ruler.distance([30.51, 50.32], [30.52, 50.312]);

Creating a ruler object

cheapRuler(latitude[, units])

Creates a ruler object that will approximate measurements around the given latitude. Units are either kilometers (default) or miles.

cheapRuler.fromTile(y, z[, units])

Creates a ruler object from tile coordinates (y and z). Convenient in tile-reduce scripts.

var ruler = cheapRuler.fromTile(1567, 12);

Ruler methods

distance(a, b)

Given two points of the form [x, y], returns the distance. Typically within 0.1% of turf.distance values but 20–25 times faster.

lineDistance(points)

Given an array of points, returns the total line distance. Typically within 0.1% of turf.lineDistance values but 20–25 times faster.

bearing(a, b)

Returns the bearing between two points in angles. Typically within 0.001% of turf.bearing but 3–4 times faster.

bufferPoint(p, buffer)

Given a point, returns a bounding box object ([w, s, e, n]) created from the given point buffered by a given distance.

var bbox = ruler.bufferPoint([30.5, 50.5], 0.01);

bufferBBox(bbox, buffer)

Given a bounding box, returns the box buffered by a given distance.

insideBBox(p, bbox)

Returns true if the given point is inside in the given bounding box, otherwise false.