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Comparison of kmz and jnx maps for Garmin GPS units

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On the new GPS units like Oregon, Dakota, Montana, 62 etc, Garmin has allowed the operation with the native raster maps.

Oregon 550 and raster maps

Native raster maps can be used on 2 ways:
  • Custom maps. Raster maps are stored in kmz files. Each kmz file is divided in jpg tiles. The limitation is 100 jpg tiles and slow operation. Zoom and scroll functions of kmz maps are very slow. Garmin has intentionally slowed down the rendering process of kmz files. Custom maps can be designed according to the official procedure available here. The same kmz files can be shared between different Garmin GPS units.
  • Raster maps in jnx file. Starting with BirdsEye service jnx files are available for the new Garmin units. Jnx files includes the calibrated map data including the encryption of unit ID number. Each Garmin GPS unit has a different ID number so jnx files can not be shared between different GPS unit supplied with the official firmware. Garmin has designed jnx file structure to provide the paid service for professional designed topo maps. The main advantage over kmz custom maps is the enabled fast rendering speed so zoom and scroll functions are really fast. No need to use paper map, you can scroll the huge area in few seconds. The second advantage is very high tile limit, so each jnx map can cover very large area. Garmin has not provided the data structure of jnx maps.

To design and upload the jnx map in Garmin GPS unit 2 workflows are available:

  • The calibrated raster map like GeoTiff should be converted with the tools like OkMap and MAPC2MAPC to jnx first stage file format (JFSFF). JFSFF does not include the encrypted ID number of the GPS unit so you can not use JFSFF in the GPS units with the regular firmware. There is the procedure how to change the firmware and use JFSFF but in this case you void Garmin's warranty.
  • The second choice is to activate BirdsEye account. Transfer JFSFF file in the BirdsEye folder of your Garmin GPS device main memory. Start BaseCamp program. Add JFSFF file to My collection. View My collection, right click on JFSFF file and than activate the function send to external micro SD card memory of Garmin GPS unit. You should be connected to Internet and BaseCamp will check your BirdsEye subscription and then encrypt the new jnx file on your micro SD card. Delete JFSFF file in your main memory, disconnect GPS unit from PC, enable in Setup - Map - Select Map jnx raster maps and your jnx map on micro SD card is ready to use. This process has been verified with BaseCamp versions 3.1.3 and 3.2.2 only. Check below comments.

Below is the short video showing the difference in scrolling and zooming speed of kmz and jnx maps on Garmin Oregon 550 (firmware version 4.50).


The advanced users can find more details on the following links:

JNX and KMZ maps,

GPS underground forum thread related to jnx maps,


OkMap tool.


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