Category Archives: GPS/Geo

Public Geo Data

The nice people of Public Geo Data have started a petition and a campaign for letters to be sent to ministers for the environment.

This is a quite important issue, especially in the these times of mash-ups everywhere. If the data — that has already been payed for by taxpayers — must be bought once more by every user, development in this area will be stuffed, and we won’t get to see the advantages that these types of information can bring.

I have already written to the Danish Minister for the Environment, the relevant member of the Danish parliament, and of course my member of the European Parliament.

I think you should too: Contact Your Minister.

[via Mapping Hacks.]

Digital Camcorder Considerations

We want to get a digital camcorder.

There’s a wedding coming up, some travelling, later perhaps more interesting “subjects”, and then of course there’s the gadget dimension.

Among the criteria for selection are:

  • Relative ease of use: OK, I’m geeky, but devices with less than 85 keys are often impossible to figure out…
  • Dependability: We’re prepared to back up to HD and other media, but we still want to be able to trust the media.
  • Quality: The raw footage should be raw, not compressed. The images are more important than the sound.
  • Future proof: I know, not possible in this world, but it seems it’d be OK to go for HD?
  • Comfortable: Small and handy, likely to just be available and ready to go when needed.

Currently on the short list is the Sony HDR-HC3. Compared to its predecessor, the HC1, there are improvements as well as changes to the worse, but overall it seems it’s progress.

What to do?

ObSemWebAngle: Ideally, it should also include GPS integration and other ways of content description! ;-)

Garmin Geko 201 and RDF

Note: This post originated outside of the weblog, but I figured it really belongs here, and it makes it easier to find.

Following in the footsteps of Matt Biddulph, I acquired a Garmin Geko 201 GPS unit, wanting to annotate my digital photographs with location information.

Matt also wrote a Python script to extract the tracklogs and waypoints from the unit and turn them into RDF statements.

I tried it out, and found I had to overcome some dependency problems, as well as do a little tweaking to get all the information I wanted.


The following dependencies applied to the script on my almost clean Redhat 9 laptop installation with Python 2.2.2:

  1. PyGarmin, which itself doesn’t have any dependencies. It did however need a little patching (diff for to keep Python from complaining.
  2. Redland, with Python interface.

The libraries should be installed in reverse order…

Waypoints tweaking

To keep my version of Python (2.2.2) from crashing, I had to fix some import statements in the original version of Matt’s Also, a variable name clash was resolved.

Now being able to output an RDF model, I noticed the waypoints only had a property (dc:title) for the name given to it in the unit, but no indication of the symbol used (such as a house, an airport or a building icon). I figured it would be nice to be able to use that information as well, and decided to map each symbol to a Wordnet term, through the use of the Wordnet 1.6 vocabulary namespace.

The Garmin Protocol Specification defines a number of symbols, but the Geko 201 only has a subset of these (and two additional symbols not defined in the specification).

Each numeric symbol ID is mapped to a string identifier such as sym_airport, which in turn (for the Geko 201 symbols only, it’s not easy to create a sensible mapping) is mapped to a Wordnet noun, indicating which type of place is marked. This also fits in nicely with the spacenamespace effort.

When outputting the RDF model, each waypoint is assigned an rdf:type of the wordnet term if found. If no term is found, the string identifier is output as the literal object of a property, and if no string identifer is found, the symbol ID is output as a literal object of a property.

Waypoint symbol mapping

Some of the symbols used relates to verbs, but places need to be identified by nouns. The mapping below doesn’t seem perfect, comments and suggestions are welcomed, especially regarding what to call a place with information (as well as the two special Geko 201 symbols, 8255 and 8256, a closed and an open box)…

Symbol ID String identifier Wordnet term
0 sym_anchor Harbour-1
6 sym_dollar Bank-4
7 sym_fish Fishery-1
8 sym_fuel Gas_station-1
10 sym_house Home-1
11 sym_knife Restaurant-1
14 sym_skull Danger_zone-1
18 sym_wpt_dot Train_station-1
19 sym_wreck Wreck-4
150 sym_boat_ramp Lake-1
151 sym_camp Campground-1
152 sym_restrooms Restroom-1
155 sym_phone Telephone-1
156 sym_1st_aid Hospital-1
157 sym_info Information-2
159 sym_park Park-1
160 sym_picnic Park-2
161 sym_scenic Sight-2
162 sym_skiing Mountain-1
163 sym_swimming Beach-1
170 sym_car Parking_lot-1
171 sym_deer Zoo-1
173 sym_lodging Lodging-1
175 sym_trail_head Spot-1
178 sym_flag Place-1
8197 sym_golf Golf_course-1
8234 sym_building Building-1
8255 sym_8255 Place-1
8256 sym_8256 Place-1
16384 sym_airport Airport-1
16395 sym_parachute Amusement_park-1



… to mattb and danbri for making this possible.