RogerBW's Blog

Viking is a powerful, but not always intuitive, program for handling geodata (position log recordings, maps, etc.). This post deals with how to plan a walking route using it.

First, set up Viking with a map layer. (I have it configured to bring up OpenStreetMap Mapnik tiles on start; OSM has become my preferred mapping service, both because it's properly free and because its coverage of non-car routes – and increasingly car routes too – is the best available.)

• Pick an approximate area. I'm going to plan a short walk round a local (but hilly) wood.

• Make a TrackWaypoint layer (right-click on the layer subwindow, or on the "+" at the bottom.

• Start a track ("Create Track" or shift-ctrl-T). You'll be asked for a track name when you click on the first point. Click on points as necessary to make your series of straight lines more or less line up with the paths you want to take. (Strictly speaking you should only need to click on each point where you have a choice to make, but that's often not enough to be clear about which path to use, especially if there are multiple paths between the same pair of points.) Right- or middle-click deletes the most recent point; ctrl-arrow keys let you scroll around, and ctrl-+/- or mouse wheel lets you zoom in and out. (Or you can shift over to the normal panning control with ctrl-shift-P, and back to the track creation mode with ctrl-shift-T.) You'll get a total distance readout by the mouse pointer.

• When you've finished, right-click the TrackWaypoint layer and "Finish Track". If you click on the triangles and go down to the actual track layer, then right-click and select Properties, you can add automatic distance labels. "Statistics" will show you the total length of the track.

• You now know how long this route is, but not what the hills will be like; I tend to try to avoid hard climbs, or at least keep them for shorter walks. For this information you need digital elevation model data. First, click the tick-box by the Default Map layer to turn it off, so that you can be sure of what's happening. The version of Viking I'm using can't deal with the redirects on the NASA site (the best data still come from the Shuttle Radar Topography Mission in 2000; the more recent ASTER-GDEM data set is much rougher), so I've downloaded them by hand; I'll go into both methods here.

• Add a new "DEM" layer. Select it, and Tools → DEM Download. Left-click, and if the map turns brownish-yellow you've already downloaded the relevant file. Otherwise, it should automatically download and save it, but it won't work. Right-click somewhere on the map to "Show DEM File Information", and select and copy the URL. On Unix, download that (e.g. with wget) into ~/.viking-maps/srtm3-Eurasia/ – or another directory as that File Information tells you – and then left-click on the map as before to load it.

• You should now see shades of brown rather than grey. (Then you can turn the default map back on, because this isn't helpful in itself.)

• Now go into the Track layer again, right-click, and Transform → Apply DEM Data → Overwrite. This looks up the elevation for each track point.

• Now when you pull up Track → Statistics, you'll have Elevation-distance and Gradient-distance tabs. You can click on a spot within one of those graphs to jump the centre of the map window to that location. (It's only approximate, because SRTM data are at about 90m resolution outside the USA, but better than nothing.)

• In this case I have some excessive climbs that I can try to eliminate. So back to the track layer, and Tools → Edit Trackpoint (shift-ctrl-K).

• Clicking on an offending point will bring up a window with details. You can move that away and drag the trackpoint to where it's wanted. Insert After will put in a new track point half way from this one to the next one, which you can then click on and move. And you can delete points.

• When you've finished making adjustments, Transform → Apply DEM Data → Overwrite as before and look at the track statistics. Repeat as needed.

• What you do from here depends on what sort of navigation system you use while you're walking. Saving in Viking native format will be helpful if you want to edit again, but that can't be directly loaded onto a device. You can print, or generate image files for printing, if you want to look up the route on paper maps. For portable GPS devices, either Export Track as GPX or Transform → Convert to a Route, then Export Route as GPX. These will each generate a GPX file, in one case with a <trk> entity, in the other with an <rte>; how these are used depends on the device you load them into. In a future post I'll go into how to use these files with OsmAnd.