Adding features based on GPS waypoints

I use a smartphone to collect waypoint information for features. There are lots of apps that can help — I like the Locations Tagger (iOS) app.

Mapping features that do exist

I walk right up to the feature, and then capture the GPS coordinates in the app. This ruined fence can be an example.

The Location Tagger app is designed to capture Open Street Map data, so the location tags are for things like ‘Traffic light’, ‘Bridge’, ‘Shelter’, ‘Post box’ and so on. That’s not really a problem. I marked the posts of the ruined fence with the tag ‘Bridge’.

This screenshot reports accuracy of 10m, but if the field it was 5m

The apps emails the waypoint data as a file that can be read by Open Orienteering Mapper. The file itself contains the expected latitude and longitude data.

...
<wpt lat="-35.24627264592354" lon="149.082430154224">
<time>2017-04-01T15:59:06Z</time>
<name>Bridge</name></wpt>
<wpt lat="-35.24624741639499" lon="149.0823370312798">
<time>2017-04-01T15:59:62Z</time>
<name>Bridge</name></wpt>
<wpt lat="-35.24624879940902" lon="149.0822164156931">
<time>2017-04-01T16:00:11Z</time>
<name>Bridge</name></wpt>
...

Here’s how it looked after loading into Open Orienteering Mapper. I elected to join the waypoints as part of the import process.

Imported fence, with waypoints connected as an import option

I could have used the switch symbol tool to change the waypoints into the ruined fence symbol. That could be followed up with the convert to curves process and the simplify path processes on the advanced drawing toolbar.

Some of the points were a little out of line, so I decided just to draw a ruined fence directly on the map, and then delete the imported points.

The same process works well for all kinds of features: man-made objects (I tag these as traffic lights), termite mounds (post-office boxes), small boulders (bollards), boulder clusters (shelters), tracks (tagged as 10 km/h for indistinct tracks through to 40 km/h for vehicle tracks), vegetation (60km/h for thick vegetation through to 100 km/h for runnable forest).

Un-mapping features that do not exist

If I’ve marked a feature on the map, but I discover during fieldwork that it really ought not be marked, then I tag the location as a waste basket. Then I remove it from the map later.

For example, I had marked a depression on the map, based on the LiDAR relief image and profile.

Profile and relief from LASEdit

When I got to the spot, all I found was the weathered remnant of a wombat hole. It was too small to map.

It was just a small and indistinct hole

I tagged the location as a waste basket. I corrected the map when I imported the tag file.

Time to remove that depression symbol

This article is part of the Orienteering Mapping with LiDAR, Smartphones and Free Tools series.

Polite and constructive responses are always welcome.

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