When you are recording a waypoint in the field on your GPS device, the accuracy is based on your GPS fix. The number of decimal units (to the right of the decimal point) determines the accuracy of the waypoint. Even if your GPS unit supports receiving those signals, your GPX file will still use the WGS 84 decimal units. The European GPS system, Galileo, uses one called GTRF. The Russian GPS system, GLONASS, uses a different mapping system, PZ-90. Any unit that uses the GPS satellites will expect the GPX data in this WGS 84 format. For example, a coordinate in WGS 84 is -77.508333, and in traditional latitude would be S 77° 30′ 29.9988″ (degrees minutes seconds). You can simplistically think of it as a decimal equivalent of the latitude and longitude that you learned about in school ( and you convert between them with this tool). In a GPX file they are stored in WGS 84 format, which is a mapping reference system created by the U.S. Since your position is the building block of all the geographic data in the GPX file, it’s important to understand the numbers that you’re looking at.īefore I show you the GPX file data for a waypoint, we need to talk about latitude and longitude.
But if I crack open the actual GPX file from here, it will likely indicate that my position is accurate down to an atom or electron, which is obviously wrong. Understanding Latitude and Longitude in Your GPX File When I look at this position fix on my GPS, it’s saying that the accuracy is 17ft. You can take a look at (the very dry) different types of information that a GPX file can have here, but there are only a few big ones that you need to know about: waypoints, routes, and tracks. Save GPX files in the latest version, GPX 1.1, if you are given an option. Those standard tag names were first established in 2002, and then updated in 2004 with the latest version of GPX, GPX 1.1.
In order for that to work, there has to be standard tag names within the GPX file.
The GPX file format is called an “open standard” meaning that it can be used on any device for free regardless of brand. If you don’t use the tags the way they are specified here (e.g. These are some of the naming standards for a waypoint (more later). GPX Tag Naming Standards The tag names in your GPX file are all predefined and documented online.
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