Saturday Walkers Club www.walkingclub.org.uk

How To Create or Modify a GPS Track

By MarkR

There are a number of web-sites that allow you to create a GPS track by using a variety of different maps. Some of these sites allow you to use OS maps, some use OpenStreetMap data, and Google just uses its own maps.

The sites that allow you to use OS maps all have a limit imposed on them by the OS people that restricts the number of "map tiles" that can be displayed per day. This limit is shared by all users of that site and usually expires before the end of the day. Google Maps does not have any limit, but does not currently have many footpaths on its maps (though this may change as they have opened up their maps to take contributions from users). OpenStreetMap maps do have a lot of footpaths (this site also runs on contributions from users) but does not currently have all the paths that are on OS maps (but does have the occasional local path that does not appear on OS maps).

Some sites are:

  • www.maptogps.com - Has OS maps. Only supports a single path per file. Supports GPX but not KML format.
  • www.bikehike.co.uk - Has two-screen view: one with OS map, the other with Google/satellite/OSM map - quite useful. Only supports one path per file. Supports both GPX and KML.

Having OS maps available is very useful for finding footpaths, but you have limited zoom capability. Google Maps provides more zoom levels. I've been creating new paths with the bikehike site and then refining them with Google Maps.

So it depends what you want to do. Once you have created a path, you will probably want to make some edits to it to fix up any errors discovered when you actually walk the route, to alter the route in some way, or to add some way-points for points of interest. I find that the Google Maps editor is one of the better ones for ease of use and because it allows me to control more things (e.g. colour/width/opacity of the route line, adding points of interest). I therefore include below some instructions for using Google Maps editor.

How to Create a Map with Google Maps Classic

You will need a Google account (free) so that your tracks can be stored online.

Browse https://maps.google.co.uk/ If necessary, create an account and sign in.

Click "My places" near the top left of the Google Maps front page. This will show you your previous maps/searches.

DO NOT use the button "CREATE MAP". Whilst writing this, Google has changed over to a new "Maps Engine Lite" which does not currently have the ability to load a KML or GPX file. Instead click on "Or create with classic My Maps". This will show you a couple of boxes for the title and description. There is also the chance to choose between making this map Public (the default) or Unlisted (I usually select this).

If you have existing GPS data in a KML or GPX file, click "Import". This will show you a dialog where you can either click "Browse" to find a file on your machine, or enter the URL of a file. This data will then be shown on the map. Note though that many (all?) of the GPX files on the SWC web-site encode the path using way-points rather than a route. When loaded with Google Maps this will cause a series of pins to be drawn marking those way-points. This is not what I want, so I first convert the SWC GPX file into a KMZ file (which is just compressed KML) using this web page:

This conversion has the side-effect of changing the way-points into a path.

Click "Upload from file/URL". This will load the KML, KMZ or GPX data and display it on the Google map on the right side of the page. You are in edit mode so can make changes to this map - see below.

If you don't have GPS data to use as a starting point, or if you do but then want to add another path, you start a new path by first switching to draw-a-line mode by clicking the third button to the right of the compass (alternatively right-click on the map and select "Draw a line"). Click on the map where you want the path to start. Each additional click will draw a straight line from the previous point to the new location. To finish off a path, click on the last point a second time (don't move the mouse between the last two clicks). You can switch between map view and satellite view by clicking the option in the top right corner. It is also sometimes useful to use "Street View" mode (e.g. where the walk route intersects with a road. To use this just drag the yellow man onto the map - when you start to drag him the map will highlight in blue lines those places traversed by StreetView cameras. These are places you can drop him (the blue dots are photos rather than StreetView). To close StreetView and return to the map, click the "x" in the top right corner.

You can now edit the map. When in edit mode, points in the path show up as bright squares. You can drag these to new locations or right-click on the point for a menu which includes an option to "Delete this point". Note that there's also an option called just "Delete" which deletes the entire line. There's an option to undo the previous change. Between each adjacent pair of points on the line there is square that is not quite as bright. Dragging this to a new location will create another point in the line. To create a new point at the end of a line, right-click on the point at the end of the line and select "Continue this line" - you will then be back in "Draw-a-line" mode for that line. You can change the colour, width and opacity of the line by right-clicking on the line and selecting "Properties" or by clicking on the line in the list on the left of the screen. Note this has the unfortunate side effect of moving the map so the centre of the line is on the screen.

To add a Point-of-Interest to a map, right-click on the place where you want it and select "Add a placemark". You can choose from a number of icons to mark this point by clicking on the square box in the top-right corner of the placemark property box that popped up when you added the point. You can add a title and some descriptive text.

Changes you make are periodically saved. Click "Done" when you are finished. This replaces the title and description boxes with some non-editable information about the map. There should be a "KML" link here to allow you to download the track as KML, but there seems to be a bug and in order to see this option for a new map I have found that I have to delete this tab/widow of my browser and start a new one then go again to Google Maps/My Places and click on the map's name - the KML link now appears and you can click it to download the KML file to your machine.

If you want to convert a KML file to GPX format, you can use another function of the gpsvisualizer site: