Limitations of Rendering for Garmin Maps.

I copy in here a subject which I noticed when trying to render my own advanced cycle/mtb map. The actual tagging system doesn’t allow for Garmin devices to display a way with two relevant tags for the renderer.
The wiki article I’m copying from is here:
If you know a way around this then please share it here, if not then please let us try to influence all feature proposals to make it mandatory to use Highway=XX and not highway=XX and Bicycleway=XX and Path=XX… as it will be impossible to be displayed on any Garmin device (and probabely cause the same problems for all other PNAs) and likely all PDAs too.

  • Severe Limitations: It is IMPOSSIBLE right now to react to two different tags which are used to tag the same way in the database. I.E. A polyline is tagged Highway=Track and Bicycle=Yes. If you write in the .CSV file to use 0x26 for Bicycle=Yes and 0x27 for Highway=Track the mgkmap doesn’t render the way. There would be the need to introduce an IF/THEN clause into the rendering (which would heavily slow down the rendering process IMHO and make everything even more complicated). Therefore you shouldn’t write tags for Garmin maps into the csv which are like Bicycleway=Track MTB=Yes, Bicycle=Yes and so on.

The big problem is that many people tag this way. It should be tried to stop all proposals for map features and change them so that this is no problem. If a way is tagged: Highway=BicycleandFootway or Highway=TertiaryandBicycle then an appropriate rendering with typfiles will become possible. This Limitation off course also applies to any rendering for Garmin maps without TYP files.

Example of IF/THEN clause could be:

  • IF bicycle=yes; THEN render 0x21 (bicycleway) AND don’t render the Highway=XX tag; IFNOT then continue;
  • IF bicycleway=path THEN render 0x22…
  • IF Highway=XX THEN render 0x23, IFNOT then this is no street to be displayed in the bicyclemap.