I have about 600 GeoTIFF map files geo-referenced using New Zealand Transverse Mercator 2000 (NZTM2000). Each file is about 140 mb in size. I'd like to convert them to Garmin Custom Maps compatible KMZ files so people can download them and use them with Garmin GPS units.

Does anyone know a way to batch process these, preferably converting the tiff image to a much smaller jpeg image as part of the process? I'd prefer a tool that is free or donation based.

I've tried the method gdal_translate method provided as this answer https://gis.stackexchange.com/a/20936/1150 but unfortunately the KMZ files produced don't seem to be compatible with Garmin devices from the user feedback I've had. An example file produced using gdal_translate - https://dl.dropboxusercontent.com/u/48119/CB12-test.kmz

OkMap produces valid KMZ files but it lacks a useful batch processing option. OkMap also produces KMZ's that are much smaller that those produced through gdal_translate which is a nice bonus. Perhaps someone knows a technique / workaround I could use to automate OkMap not using the command line?

  • I use OkMap and agree a batch process would be nice. For batch work have you seen this? gis.stackexchange.com/questions/92354/…
    – John
    Jul 16, 2015 at 12:23
  • @johns I hadn't seen that - I'll investigate and if anything works I'll post it as a solution here. Thank you.
    – Gavin
    Jul 16, 2015 at 21:44

2 Answers 2


OkMap desktop version now has a bulk "Maps conversions" function available from the following menu option:

Utilities > Maps > Maps conversions

This allows GeoTIFF's to be converted into Garmin Custom Maps KMZ files.


A more manual method is the below python code


Which I adapted from


This uses PyQGIS to make a .kmz with tiles

  • I haven't played in this space for a while (still using OkMap), but my previous experiments with the gdal tools produced KMZ files that were unusable by Garmin devices. Unfortunately I don't have a Garmin device myself so was relying off end user feedback at the time. But I do see there's some Garmin specific notes in readme of the github link you provided, so maybe I should have another play.
    – Gavin
    Feb 18 at 20:40

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