Stephane’s thoughts corner…

Stephane Bailliez's thoughts on everything

I’m still in the process of reviewing pictures from Tanzania and have gone past the geotagging part. I have uploaded a few more on Flickr, and you can see what the result on it on the Flickr map.

The Yahoo! Satellite pictures are of terrible quality but still it’s pretty nice. If you want to be more fancy you can use Google Earth via the KML feed.

I’ll give a bit more details on how I’m doing things. It’s far from optimal and there’s still and long way to go, but tools are getting there and my workflow will learn from this.

In January, in anticipation of the trip, I bought a Super Trackstick GPS data logger. The objective was to use it to log waypoints without having to bother much about batteries as it could supposedly last several weeks due to a motion sensor and configurable intervals and wobble. I had a bit of a trouble actually locking on GPS signals while in the Netherlands (which is not exactly known for its tall buildings and mountain-filled landscape) but I took it on the trip.

The Kilimanjaro hike can be classified as mostly a failure in term of waypoints collection. I could get GPS locks fairly easily, but due to my lack of use with the Trackstick and my fear it would suck a massive amount of batteries, what I did was actually to switch it on and off at interesting points and when taking pictures (and when I did not forget about it).

It was badly configured so there are no chance I could keep the bugger running for 7-days, the settings I had would have filled the 4MB memory in about 2 to 3 days.

The TrackStick eats batteries like popcorn in some occasion (ie: sometimes it seems to lock and drain batteries faster than you can blink). In any case, I got about 550 waypoints in 6 days and it died before reaching the summit so I got 0 waypoints on the last ascent. I was busy enough ascending and putting one foot after the other.

Problem with the TrackStick is also that once you’re in the wild, forget about changing the settings, you’re stuck with it as you need your laptop and the software to reconfigure it. (Well you could bring your laptop on the mountain and a solar panel, but I’m not yet in that camp)

When I got back to town and before going on a safari, I set it to saving mode and log every 15s and bought a set of new alkaline batteries. (I naively thought that 8 aaa 1000mAh rechargeable batteries would be enough so I did not bring the charger).

During the road trip and the whole safari, I had generally no problem getting a lock, I managed to get about 3500 GPS waypoints per day (that’s a lot of data and is actually too much) and most pictures do have an associated GPS waypoint within an acceptable range. I used a 300s maximum time difference with no interpolation (closest point).

The one that don’t actually have any match are when the GPS was not running (early morning, late evening) but those could be set manually as they are well-known location (camp or hotel location, etc..)

A bit of a warning when doing the geotagging though, timezone is not recorded on EXIF and I always set the camera to local time. GPS time is recorded on UTC so my pictures do have a +3 offset.

For geotagging, I googled around and tried GPicSync which is basic but did the job very well (like many similar tools, it’s using exiftool behind the hood, so forking a process per image is not exactly blazingly fast). I converted the trackstick logfiles to GPX format and applied the corresponding one to the appropriate folders (I classify pictures by day – so each folder is named ‘yyyy-mm-dd’).

When you need to geotag pictures one by one, though, it falls short. So what I did with the one that don’t have any waypoint was to use geosetter, save the GPS template for the known GPS coordinates and apply it to the ‘missing’ pictures.

I tried the LightRoom geotag plugin but it failed all over the place and was not consistent in its execution so I gave up for that.