n-vector
Stability: 1 - Experimental
Normal vector and a distance function to determine central angle between normal vectors.
Contributors
Installation
npm install n-vector
Tests
npm test
Visual test
npm run sketch
Usage
var NVector = ; var position1 = NVector;var position2 = NVector;var centralAngle = NVector;// 0.0036406600953623955var greatCircleDistanceInKm = centralAngle * 6371; // Earth radius ~6371km// 23.194645467553823 kmvar greatCircleDistanceInMi = centralAngle * 3959; // Earth radius ~3959mi// 14.413373317539724 mi
Overview
The normal vector to the Earth ellipsoid (called n-vector) is a non-singular position representation that turns out to be very convenient for practical position calculations.
source: A Non-singular Horizontal Position Representation
The non-singular aspect of n-vector makes the calculations required simple and without special cases to consider that are present when dealing with crossing prime meridian and at the Earth poles. For a deeper and more precise explanation see A Non-singular Horizontal Position Representation.
Documentation
NVector
Public API
- NVector.DEGREES_TO_RADIANS
- NVector.distance(a, b)
- NVector.fromLatLon(latitude, longitude)
- new NVector(x, y, z)
NVector.DEGREES_TO_RADIANS
DEGREES_TO_RADIANS
: Number 0.0174532925, multiplier to convert decimal degrees into radians.
NVector.distance(a, b)
a
: NVector First normal vector.b
: NVector Second normal vector.- Return: Number Central angle between
a
andb
(multiply by sphere radius to determine the great circle distance).
Returns a central angle between two instances of NVector
. To get actual distance, multiply the central angle by the estimate of Earth's radius (if it was a perfect sphere), 6371km or 3959mi.
NVector.fromLatLon(latitude, longitude)
latitude
: Number Latitude in decimal degrees (ex: 31.565665).longitude
: Number Longitude in decimal degrees (ex: -96.811523).- Return: NVector Normal vector corresponding to given latitude and longitude.
Creates a new NVector
instance from given latitude and longitude.
new NVector(x, y, z)
x
: Number NVector "x" component.y
: Number NVector "y" component.z
: Number NVector "z" component.- Return: NVector Normal vector with
x
,y
, andz
components.
Creates a new NVector
instance.
Sources
The implementation has been sourced from: