GPX, or GPS eXchange Format is an XML schema designed for transferring GPS data between software applications. It can be used to describe waypoints, tracks, and routes. An XML schema is a description of a type of XML document, typically expressed in terms of constraints on the structure and content of documents of that type, above and beyond the basic syntax constraints imposed by XML itself. ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ... A waypoint is a reference point in physical space used for purposes of navigation. ... A course, in navigation, is the direction of travel. ...

Data types

In GPX, a collection of points, with no sequential relationship (the county towns of England, say, or all Skyscrapers in New York), is deemed a collection of individual waypoints. An ordered collection of points may be expressed as a track or a route. Conceptually, tracks are a record of where a person has been, routes are suggestions about where they might go in the future. So, for instance, there might be timestamps for each point in a track (because someone is recording where and when they were there), but timestamps for each point in a route are unlikely to be provided, because the author is suggesting it, and nobody might ever have travelled it. A waypoint is a reference point in physical space used for purposes of navigation. ...

The minimum properties for a GPX file are latitude and longitude for a single waypoint. All other variables are optional.

Structure

 <?xml version="1.0" encoding="UTF-8" standalone="no" ?> <gpx ...> Metadata <metadata> ... </metadata> Data Eg: Track Waypoint <trk> <wpt lat="#" lon="#"> <trkseg> <ele>#</ele> <trkpt lat="#" lon="#"> <name>...</name> <ele>#</ele> ... </trkpt> </wpt> <trkpt ...> <wpt ...> ... ... </trkpt> </wpt> </trkseg> <trkseg> <trkpt ...> ... </trkpt> </trkseg> ... </trk> File end </gpx> 

Example

 <?xml version="1.0" encoding="Windows-1252" standalone="no" ?> <gpx xmlns="http://www.topografix.com/GPX/1/1" creator="byHand" version="1.1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd"> <wpt lat="39.921055008" lon="3.054223107"> <ele>12.863281</ele> <time>2005-05-16T11:49:06Z</time> <name>Cala Sant Vicenç - Mallorca</name> <sym>City</sym> </wpt> </gpx> 

Example of Garmin WAYPOINT extensions

 <?xml version="1.0" encoding="Windows-1252" standalone="no" ?> <gpx xmlns="http://www.topografix.com/GPX/1/1" xmlns:gpxx = "http://www.garmin.com/xmlschemas/GpxExtensions/v3" creator="GeePeeEx Editor" version="1.1" xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensions/v3/GpxExtensionsv3.xsd"> <metadata> <link href="http://GeePeeEx.googlepages.com"> <text>Specialised editor for Garmin Automotive units.</text> </link> <time>2007-06-10T01:38:55Z</time> <bounds maxlat="53.113007" maxlon="-1.333593" minlat="53.113007" minlon="-1.333593"/> </metadata> <wpt lat="53.113007" lon="-1.333593"> <ele>0.00</ele> <time>2007-06-10T01:38:55Z</time> <name>UK1</name> <desc>desc - line 1 desc - line 2 desc - line 3 desc - line 4 <font color=red size=+4>RED</font></desc> <sym>Information</sym> <extensions> <gpxx:WaypointExtension> <gpxx:Proximity>305</gpxx:Proximity> <gpxx:DisplayMode>SymbolAndName</gpxx:DisplayMode> <gpxx:Address> <gpxx:StreetAddress>Street Address 1</gpxx:StreetAddress> <gpxx:StreetAddress>Street Address 2</gpxx:StreetAddress> <gpxx:City>city here</gpxx:City> <gpxx:State>state here</gpxx:State> <gpxx:Country>country</gpxx:Country> <gpxx:PostalCode>PostCode</gpxx:PostalCode> </gpxx:Address> <gpxx:PhoneNumber Category="Phone">123</gpxx:PhoneNumber> <gpxx:PhoneNumber Category="Phone2">456</gpxx:PhoneNumber> <gpxx:PhoneNumber Category="Fax">789</gpxx:PhoneNumber> <gpxx:PhoneNumber Category="Email">bill@microsoft.com</gpxx:PhoneNumber> </gpxx:WaypointExtension> </extensions> </wpt> </gpx> 

See also

• Point of Interest
• Exchangeable image file format
• Geography Markup Language
• Keyhole Markup Language, the equivalent format compatible with Google Earth.
• UTC

A point of interest, or POI, is a specific point location that someone may find useful or interesting. ... Exchangeable image file format (official abbreviation Exif, not EXIF[1]) is a specification for the image file format used by digital cameras. ... The Geography Markup Language (GML) is the XML grammar defined by the Open Geospatial Consortium (OGC) to express geographical features. ... KML (Keyhole Markup Language) is an XML-based language for managing the display of three-dimensional geospatial data in the programs Google Earth, Google Maps, Google Mobile, ArcGIS Explorer and World Wind. ... Google Earth is a virtual globe program that was originally called Earth Viewer and was created by Keyhole, Inc. ... ...

External links

• Official GPX web site
• TerraWiki: Project to build an digital database for outdoor activities using GPS data. May have been www.tierrawiki.org

References