Leon's Weblog

January 21, 2007

Maps for GPS Tuner

Filed under: Gadgets,Software Dev — Leon @ 10:34 pm

I have been looking for an off-road navigation solution when I stumbled across GPS Tuner. While TomTom is great for car navigation, it lacks many features such as track recording and support for custom maps. We now have the option of using the newly released mobile Google Maps and mobile Virtual Earth, these programs require a constant Internet connection and can be slow to use (especially when hiking in remote locations with poor cell phone reception). Its often much more convenient to have the needed maps pre-loaded and configured on the hand-held.

When I gave GPS Tuner a try I quickly realized that I have to spend a lot of time making my own maps. Luckily, there are a number of free online mapping systems (tile servers) such as Google Earth and Virtual Earth that can provide the base images for maps. The problem now is downloading the maps (in fine resolution) and piecing them together. Since I’m too lazy to do this manually, it was time for a little scripting to automate the process.

Google Maps and Microsoft Virtual Earth work by asynchronously downloading tiles of the map depending on the users desired map zoom level. With a little hacking, I figured that I could put together a script that will download any section of the map in any available zoom level and automatically put all the tiles together into one large image. The biggest challenge there is finding out the indexing scheme used for the tiles (i.e. given a lat/long coordinate and a zoom level deterministically determine the corresponding tile on the map and the URL to fetch that tile). The following articles on Via Virtual Earth gave me a great head start and even some sample code. All that was left to do is write a loop to download all the tiles between two lat/long coordinates and save them into one continuous image that can be loaded into GPS Tuner.

Here is the code and a sample image of Manhattan made from about 100 tiles.

Happy Navigating.

January 14, 2007

New Toy: Eten M700 (glofiish)

Filed under: Gadgets — Leon @ 1:20 am

Eten M700 (glofiish)
Just got a new M700 to replace my old phone (Motorola MPx220) and PDA (iPaq 3900). On first impression, this is a great convergence device but its takes some time getting used to. The Eten Users Forum was a big help in working out the kinks and getting everything setup.

Caveats

  • Static Navigation: The GPS receiver has static navigation turned on by default. This limits position changes to about every 50 meters and makes the device unusable for navigating on foot. Use SirfTech to disable this option (be careful). Refer to the following thread for details.
  • Battery Indicator: The battery seems to continue charging indefinitely (even when the indicator shows 100%). The charging light does turn off an hour later… this is “normal.”
  • ETEN software: For lack of a better word, the ETEN software sucks. Replace it with another vendor’s version if you need that functionality. The device runs faster and with less “hick-ups” once the ETEN software is removed.

Key Applications

  • TomTom Navigator – This is the best navigation software that I found. Just copy the maps to your SD card and you are ready to go. (make sure to get at least a 1GB card)
  • GPS Tuner – Great for off road navigation and making custom maps.
  • Tube II – Transit maps and city reference.
  • Resco Explorer – Powerful file explorer, registry editor, network browser.
  • Resco Photo Viewer
  • SPB Pocket Plus, Diary, and Weather – Convenient today screen plug-in and task manager. Great for one handed navigation of PIM data. Note that the current version has a problem with the Glofiish which causes stray lines to be drawn on the today screen tabs.
  • Pocket Informant – Comprehensive PIM manager.
  • HiCalc – Comprehensive calculator
  • Lexisgoo – Great dictionary.
  • Windows Live Search (still in Beta)
  • SK Tools – I didn’t believe the hype at first but it actually does make the device run faster.