thoughtgap/gpx-local-to-utc

Adjusts local gpx timestamp which think they are UTC to actual UTC.

GPX Timezone Corrector

The GPX Timezone Corrector is a Node.js script designed to correct timestamps in GPX files. Many GPS Receivers and mobile track recorder apps save the GPS track timestamps by using local time, but adding a UTC 'Z' indicator at the end. When reusing this data, the timestamps get imported as UTC, resulting in an undesired time offset.

The script dynamically adjusts timestamps based on the geographical location, taking into account the correct timezone and daylight saving time adjustments.

Example

<trk>
   <trkseg>
     <trkpt lat="43.291821023449302" lon="-0.369691969826818">
       <ele>180.92570000000001</ele>
       <time>2013-07-28T23:07:14Z</time>
     </trkpt>

• For each track, the first trackpoint's timezone is determined. The example coordinates are in Europe/Paris.
• The date 2013-07-28T23:07:14 (dropping the UTC indicator as it refers to local time) is assigned Europe/Paris timezone. As it was DST in July 2013, it results in a 2h negative offset to UTC. The result is 2013-07-28T21:07:14Z.
• The -2h offset will be applied to all trackpoints in the segment.
• For the next track in the GPX file, the timezone and offset are determined separately.

Prerequisites

• Node.js (version 12.x or higher recommended)
• NPM (Node Package Manager)

Installation

Clone the repository, then install the necessary dependencies:

git clone https://github.com/thoughtgap/gpx-local-to-utc
cd gpx-local-to-utc
npm install

Usage

To correct timestamps in a GPX file, run the script with the path to your GPX file as an argument:

node index.js path/to/your/file.gpx

The script will process the file and generate a corrected version named file_corrected.gpx in the same directory.