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Jeff Fort read my post concerning the installation of TomTom POI from a Mac. Jeff is into geocaching, and asked if I knew a way to get waypoints into TomTom Navigator 5 on his Palm from his Mac. While I'd heard of Geotagging (with reference to tagging images with GPS co-ordinates), my first step was to find out something about geocaching. Then I could start looking at the problem...

According to Wikipedia:

Geocaching is an outdoor activity that most often involves the use of a Global Positioning System ("GPS") receiver or traditional navigational techniques to find a "geocache" (or "cache") placed anywhere in the world. A typical cache is a small, waterproof container containing a logbook and "treasure", usually trinkets of little value. Participants are called geocachers; those not familiar with geocaching are called geo-muggles or just muggles, a term borrowed from the Harry Potter series. Geocaching is similar to a much older activity called letterboxing. The major difference is its use of the GPS and the Internet.

Err... interesting! The Geocaching.com website has a great tagline: "The sport where You are the search engine". An exchange of e-mail determined Jeff had the following requirements:

1. To download a geocaching.loc file from http://www.geocaching.com;
2. To use GeoNiche, a Palm app, to view the data when walking;
3. To get the data in the .loc file into .pdb format for GeoNiche using the Java applet EasyNiche);
4. To use the same waypoints in the file from 1. with TomTom maps in order to find the locations in the car. As Jeff explains "The problem is getting in the general area of the target on streets. That's why it would be great to see the points as POIs in TomTom and then, when you get out of the car, switch to GeoNiche and go hiking/searching."

Between us, we came up with a solution to no. 4 without having to involve a Windows PC. The full sequence follows, which is hopefully easier to replicate than Korean research into stem-cell cloning.

Download the .loc file

A .loc file is the original download format for search results on Geocaching.com:

After registering for a free account a Geocaching.com, I downloaded a .loc file for a cache in the Peak District, near to where I live:

Convert the .loc file into a POI .ov2 file

Open your web browser and navigate to GPS Visualizer. This is a web-based front-end to GPSBabel (and more) implemented by Adam Schneider. Using the drop-down menus set the interface to input the .loc file you just downloaded, and output a TomTom POI file (or just use this shortcut) then click Convert the file:

All being well, you should see a message like this:

Right-click (or control-click) on the file geocaching.ov2 to save the file (it's not a format Safari will recognise, so don't single-click on the link to the file). In your downloads folder (perhaps on your desktop, depending on your browser preferences) you should find a file called "geocaching.ov2.txt" (if using Safari). Notice the .txt extension (it's not added by Firefox)? We don't want this, so rename the file to just "geocaching.ov2" and click "Use .ov2" when the Finder protests:

Create the POI icon

According to the TomTom SDK:

...each POI type in an external POI file can optionally have a user?friendly name and an icon. The icon must be a .BMP file in the same directory as the external POI file. It is recommended that icons have a size of 22 by 22 pixels.

Furthermore, according to PocketGPSWorld:

User customisable POI databases are arranged in files (with an ov2 extension) these also come with a graphic .bmp file. Both must have the same name to work together... The restrictions are that it must be 256 colour 8 bit .bmp format file. If it is not then it can cause TomTom Navigator to crash.

This tells us what we need to know to build an icon to go with our geocaching.ov2 file. I made a screen selection of the Geocaching.com logo (Command-Shift-4), which saves a file named something like Picture 1.png to your Mac desktop. I used GraphicConverter to open this file to:

1. Change the size to 22 x 22 pixels;
2. Change the colour bit-depth to 256 colours (8-bit);
3. Save the file as a Windows .bmp file named "geocaching.bmp".

Make the POI available to TomTom

Mount the TomTom SD card on your Mac desktop (using Missing Sync, or an SD card reader). The POI files (geocaching.ov2 and geocaching.bmp) should be placed inside the TomTom map folder where they will be used (here, the Great_Britain_Map folder):

Finally, check that the new POI files are activated in TomTom:

With TomTom running:

1. Tap Change preferences;
2. Tap Manage POI;
3. Tap Enable/Disable POI;
4. Check geocaching has a check-mark next to it;
5. Tap Done x 2.

Try it out

In Navigator tap the screen, then Navigate to..., selecting Point of interest, where you should see your new geocaching POI. TomTom can now lead you as close as you can get by car:

Thanks Jeff; my wife and I may have just found a new hobby!

Update 15.01.06: We tried it out today using a Palm T3 paired with a Navman 4400 Bluetooth GPS receiver, TomTom Navigator 5 for PDA (to get near the first target in the car—even though we knew the way!), GeoNiche for Palm (for navigating to targets on foot), and the above Mac-based know-how. Some of the muggles may have noticed our suspicious behaviour.

"The sport where You are the search engine" indeed! Assimilate that, Google! Speaking of Google, you can view the geographic relationships of local caches using Google Earth for Mac (although the icons don't always show; it is currently a beta product!). Click the link to "Download Geocache browser in Google Earth" in the My Account area on Geocaching.com. This will download a KML file which you load into Google Earth:

Jeff points out that out that with a premium geocaching.com membership, you can do a "pocket query" and not be limited to 20 results per page as when searching for waypoints with a basic membership. If you want more than 20 waypoints installed at a time I see two options: (1) Create a second file set: geocaching2.ov2 and geocaching2.bmp. You can of course name them however you like—as long as the name of the .ov2 and .bmp files are the same bar the extension. This should load and display both sets of waypoints into TomTom as if it were one; (2) Combine .loc files before conversion. It's easy to see which bit describes an individual waypoint due to the XML-like data structure. You could copy-and-paste as many of these as you like into one .loc file, then convert to .ov2 for TomTom or .prc for GeoNiche.

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