NZ Open GPS Project

Community developed auto-routing maps of New Zealand

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Maps for legacy GPS units

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Maps for Legacy GPS units - aka Lofi maps

Recently I started kicking around the idea of bringing my old Legend out of retirement to use as a bike computer.


I realised the maps that I produced for it over 4 years ago were very outdated and hellishly slow to re-draw on the Legend.

As a test I loaded a tile of the current auto-routing maps, and found they were even slower and updated so slow they couldn't be used while driving and be of use. Even updating at bike speeds was a bit touch and go! The modern maps draw slowly on the Legend as the tiles are quite large - a couple of megabytes in size and compiled at a TRE size of 2000 - 5000. Modern units like the Nuvi and 60Cx draw these quickly with no lag, while the Legend struggles for many seconds to draw the map. By the time it's drawn, the position has moved and it has to re-draw them all over again.

My initial tests showed that I could wring a faster re-draw on the Legend by recompiling the maps to a smaller TRE size (500) and gain some useful speed. The real change in re-draw speed came when I split the NZ maps into tiles 1ox 0.25o giving 320 tiles (separate maps) with most being a couple of hundred kb and the largest being 1.3 megabytes. All the tiles except the largest were compiled at a TRE size of 5000. I compiled the largest tile (Auckland at TRE = 500) which gives fast updating speed and a reasonable tile size. More technical material is available further down the page. Please make sure you have 'lock on road' turned off in the map setup menu. Lock on road slows down the processing on the GPS unit something chronic!




The maps may not be updated, but they are up to date as of May 2009. They contain all the features of the current auto-routing maps except the auto-routing and the POI files (you can add the POI files from and )


Download the Lofi maps from

Use the index PDF to determine which map tiles to load. You should be able to fit around 70% of either the North or South Islands into a 8mb blue Legend.

Use SendMap to load the maps onto your GPS from

More Detail

I started with a fresh copy of the source files of NZ - downloaded from - the source files are clearly marked.

I merged all of the tiles into one large map in GPSMepEdit and set the TRE size to 5000.

At this stage suggest using the menu path Edit | Select | By type and choose Walkway/trail 0x0016 Right click, modify, extend all elements up to level 2, then repeat and extend to level 0. Save

The map splitting was done in GPSMapEdit using, Tools | Split map to files | Custom |  1ox 0.25o

I then did a quick batch file to capture the file names

dir *.mp >filelist.txt

Using Excel I built another batch file to correct all the file names:


And then also a batch file to compile the source files into ready to use .img files.



Last Updated on Friday, 05 March 2010 06:20