Thursday, 24 August 2017

Editing GPS coordinate data with the Prune GPS Tool

This is a great tool when working on GPS track files (.gpx) that are downloadable from the internet.

You can view tracks (e.g. recommended walks) overlaid on a map, and edit the route by adding, deleting or simply dragging the data points to a different location.

And once you have made your changes, you can copy the .gpx files to your Garmin GPS ready for your next outing.

While recently preparing for a short holiday in Devon, I fired up my Garmin eTrex 10 and replaced the local maps with those for mid/east Devon. Check this earlier post on how to load free topographical maps to an eTrex 10:

I also looked around for some suitable walks with GPX files and came across this excellent website:

Having downloaded a walk around Morchard Bishop, I noticed a slight problem with the title, and wondered whether there was a better way of changing the name than using a simple text editor. This search led me to the Prune GPS Tool: gpsprune

viewing a track

When a .gpx file is opened in GpsPrune, the editor may initially show just the track outline. But by clicking the "show map" icon (the globe) you can view the track overlaid on a map which is automatically downloaded from OpenStreetMap.

The small toolbar (top centre of screen) contains the following tools:-

  • slider: fade in/out the detail (e.g. fully left shows map only, fully right shows track only).
  • ruler: enable/disable the scale (bottom left).
  • Earth/globe: enable/disable map view
  • crossed arrows: toggle move map/move track
  • track points: toggle view points only/track only/track & points
  • hand: toggle view only/edit track

Use the + & - zoom controls as necessary.

I decided to remove the bottom section of the walk and extend it to the east, to take in another footpath. So I just needed to get to grips with the editor.

editing a track

To put GpsPrune into edit mode, toggle the hand icon (or you can hold down "Alt Gr" for each edit operation).

To move a track point, simply left-click and drag to new location.

To add a point between two points, click on the cross-arrows to disable map move, then left-click & drag on the track between two points (Note: the map-move option is auto enabled if you do this without the mouse over the track).

To delete a point, highlight it then press delete key.

Once everything is to your liking, go to File > Export GPX and enter a suitable name to appear on your Garmin (e.g. Morchard Bishop 5m3). I like to include the distance in the title, in this case 5.3miles.

A couple of points to note:-

  1. although GpsPrune refers to "tracks", the actual file may be a "track" or a "route" (i.e. it may be found under either the Garmin track or route menus).
  2. the eTrex 10 can only display the first 19 characters of any name you give your route or track.

creating a new track

I think it should be possible to load a map and then create a new track, but I haven't found a way to export from OpenStreetMap in the required format (...let me know if you crack this!).  However, I can load a map automatically by entering coordinates via Point > Enter new coordinates, where I know (or have discovered) suitable coordinates for a nearby location.

I can then enter edit mode, right-click on the map, select create series of points from the pop-up menu, and start drawing a track by left-clicking. There is probably a slicker way of doing this, but it works.


This is only an introduction to GpsPrune, so I haven't covered all features and functionality of this splendid tool. But if you use your Garmin GPS when you go for walks in the countryside, this is a very useful cross-platform application to get to grips with.

GpsPrune is written in Java so should work on any compatible operating system. Ubuntu users can install from the repository.

In addition to the software, you will find lots of interesting information on the website:

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