latlng-uint

Functions for converting Latitude/Longitude to/from a unsigned integer with a specified precision.

Introduction

This library is for reading/writing LatLngs to numbers representing them as unsigned integers with a specific precision. In this way LatLngs can be stored as binary using as few bits as possible.

This way of storing LatLngs is described by National Geospatial-Intelligence Agency (NGA) in the document called Time-Space-Position Information (TSPI) NGA.STND.0019_2.0.

Unsigned integer representations of LatLngs are used with several different precisions in Variable Message Format (VMF) and this library can be used together with my VMF library.

Usage

latlng2uint(latlng, precision)

Takes as input an array representing a latlng in decimal degrees format, and an array representing the desired precision. Returns an array representing the coordinate tuple.

latlng2uint([53.80999655961908,-2.0999982476232333], [23, 24])

returns

[2507727,8486476]

uint2latlng(coordinate, precision)

Takes as input a coordinate tuple with the coordinates as unsigned integers, and an array representing the precision of the integers. Returns an array representing the coordinate as latlng in decimal degrees.

uint2latlng([2507727, 8486476], [23, 24])

returns

[53.80999655961908,-2.0999982476232333]

License and Contact

The library is developed by Måns Beckman, www.spatialillusions.com, and is provided under a MIT License.