GPX

GPX (short for GPX exchange format) is an XML file type used to store coordinates data. It is used as a common way to share coordinates amongst softwares and applications. It is defined with this open format : https://www.topografix.com/GPX/1/1/gpx-strict.xsd.

There are three data types :

• wptType: It's a Waypoint. It descibes with coordinates the position and elevation with time if given.
• trkType: A Track is made of segments containing self describing waypoints.
• rteType: It's a Route. It contains routepoints that can be distant, but as a whole describe a path between a start and an end. The void between routepoints can be filled as slef-describing waypoints and re-injected into another GPX file as a Track. GPS for instance can work that way, by having only turn-points and town to cross by, and projecting those on vector maps.

Coordinates are Latitude and Longitude in decimal degrees. Elevation is in meters. Dates and times are in UTC.

Per its specifications, a GPX file is valid as long as every single waypoint has coordinates.

For the Corsica project, I only used tracks and track segments. Here are the types I used to parse a GPX file :

export interface GPXTrkPart {
  __ATTRIBUTE__lat: string,
  __ATTRIBUTE__lon: string,
  ele: number,
  time?: string
}

export interface GPXJson {
    '?xml': {
        __ATTRIBUTE__version: string,
        __ATTRIBUTE__encoding: string 
    },
    gpx: {
        '__ATTRIBUTE__creator': string,
        '__ATTRIBUTE__xmlns:xsi': string,
        '__ATTRIBUTE__xsi:schemaLocation': string,
        '__ATTRIBUTE__version': string,
        '__ATTRIBUTE__xmlns': string
        metadata?: {
          time?: string 
        },
        trk: {
          name: string,
          type: string,
          trkseg: {
              trkpt: Array<GPXTrkPart>
          }
        }
    }
  }