helpers library
Common helper constants and unit conversion utilities used across turf functions.
Classes
- BBox
-
Please make sure, you arrange your parameters like this:
Longitude 1, Latitude 1, Altitude 1 (optional), Longitude 2, Latitude 2, Altitude 2 (optional)
You can either specify 4 or 6 parameters
If you are using the default constructor with two dimensional positions (lng + lat only), please use the constructor like this:
BBox(lng1, lat1, lng2, lat2); - CoordinateType
- Coordinate types, following https://tools.ietf.org/html/rfc7946#section-4
-
Feature<
T extends GeometryObject> - Feature, as specified here https://tools.ietf.org/html/rfc7946#section-3.2
-
FeatureCollection<
T extends GeometryObject> - FeatureCollection, as specified here https://tools.ietf.org/html/rfc7946#section-3.3
- GeoJSONObject
- GeometryCollection
- GeometryCollection, as specified here https://tools.ietf.org/html/rfc7946#section-3.1.8
- GeometryObject
-
GeometryType<
T> - LineString
- LineString, as specified here https://tools.ietf.org/html/rfc7946#section-3.1.4
- MultiLineString
- MultiLineString, as specified here https://tools.ietf.org/html/rfc7946#section-3.1.5
- MultiPoint
- MultiPoint, as specified here https://tools.ietf.org/html/rfc7946#section-3.1.3
- MultiPolygon
- MultiPolygon, as specified here https://tools.ietf.org/html/rfc7946#section-3.1.7
- Point
- Point, as specified here https://tools.ietf.org/html/rfc7946#section-3.1.2
- Polygon
- Polygon, as specified here https://tools.ietf.org/html/rfc7946#section-3.1.6
- Position
- Please make sure, you arrange your parameters like this:
Enums
- CoordinateSystem
- Coordinate reference systems for spatial data
- Corner
- DistanceGeometry
- Whether to calculate the distance based on geodesic (spheroid) or planar (flat) method.
- GeoJSONObjectType
- Grid
- Unit
Constants
-
areaFactors
→ const Map<
Unit, num> - Area of measurement factors based on 1 square meter.
- conversionEarthRadius → const double
- Earth radius in meters used for coordinate system conversions
-
coordSystemConstants
→ const Map<
String, double> - Coordinate system conversion constants
- earthRadius → const double
- Earth Radius used with the Harvesine formula and approximates using a spherical (non-ellipsoid) Earth.
-
factors
→ const Map<
Unit, num> - Unit of measurement factors using a spherical (non-ellipsoid) earth radius. Keys are the name of the unit, values are the number of that unit in a single radian
- mercatorLimit → const double
- Maximum extent of the Web Mercator projection in meters
-
unitsFactors
→ const Map<
Unit, num>
Functions
-
bearingToAzimuth(
num bearing) → num - Converts any bearing angle from the north line direction (positive clockwise) and returns an angle between 0-360 degrees (positive clockwise), 0 being the north line
-
convertArea(
num area, [dynamic originalUnit = Unit.meters, dynamic finalUnit = Unit.kilometers]) → num - Converts a area to the requested unit. Valid units: Unit.kilometers, Unit.meters, Unit.centimeters, Unit.millimeters, Unit.acres, Unit.miles, Unit.yards, Unit.feet, Unit.inches
-
convertCoordinates(
Position coord, CoordinateSystem fromSystem, CoordinateSystem toSystem) → Position - Converts coordinates from one system to another.
-
convertLength(
num length, [Unit originalUnit = Unit.kilometers, Unit finalUnit = Unit.kilometers]) → num - Converts a length to the requested unit. Valid units: Unit.miles, Unit.nauticalmiles, Unit.inches, Unit.yards, Unit.meters, Unit.kilometers, Unit.centimeters, Unit.feet
-
degreesToRadians(
num degrees) → num - Converts an angle in degrees to radians
-
lengthToDegrees(
num distance, [Unit unit = Unit.kilometers]) → num - Convert a distance measurement (assuming a spherical Earth) from a real-world unit into degrees Valid units: Unit.miles, Unit.nauticalmiles, Unit.inches, Unit.yards, Unit.meters, Unit.centimeters, Unit.kilometers, Unit.feet
-
lengthToRadians(
num distance, [Unit unit = Unit.kilometers]) → num - Convert a distance measurement (assuming a spherical Earth) from a real-world unit into radians Valid units: Unit.miles, Unit.nauticalmiles, Unit.inches, Unit.yards, Unit.meters, Unit.kilometers, Unit.centimeters, Unit.feet
-
radiansToDegrees(
num radians) → num - Converts an angle in radians to degrees
-
radiansToLength(
num radians, [Unit unit = Unit.kilometers]) → num - Convert a distance measurement (assuming a spherical Earth) from radians to a more friendly unit. Valid units: Unit.miles, Unit.nauticalmiles, Unit.inches, Unit.yards, Unit.meters, Unit.kilometers, Unit.centimeters, Unit.feet
-
round(
num value, [num precision = 0]) → num - Round number to precision
-
toMercator(
Position coord) → Position - Converts a WGS84 coordinate to Web Mercator.
-
toWGS84(
Position coord) → Position - Converts a Web Mercator coordinate to WGS84.