A picture is worth a thousand words.
Visit ttMap for further information.
It's a pretty exciting development for the Linux OS Tom Tom Go, One and XL. You can view and navigate with calibrated ecw (raster) maps.
Development of further features is ongoing.
Move over Hema Nav.Disclaimer
This software is not a professional software and its use is the sole responsibility of the user, who accepts any defects. The author of the software assumes no liability for loss or injury or loss of data that can result from a software bug, or an error made by the user during installation or use.
More info on the map file system here .