Edit 10/15:  Updated instructions below based on improvements made in GPS Visualizer to support Garmin KMZs using Google Earth.

This new post also includes instructions on how to use the GPS Visualizer overlay form to create a Garmin KMZ file, a process which bypasses Google Earth.

After Garmin’s announcement yesterday about support for custom raster maps on the Oregon, Colorado and Dakota there has been an flurry of activity as people are trying to leverage existing tools to load publicly available map data onto their Garmin receivers. I’ve found a relatively easy way to get TerraServer map data onto your Garmin using the GPS Visualizer KML overlay.

The list of digital imagery supported by the GPS Visualizer overlay tool is shown in the image below.

Before you start you will need to visit the GPS Visualizer Map Overlay page and install the GPS Visualizer Garmin overlay tool in Google Earth.  You should also have your Garmin GPS connected to your computer in USB mass storage mode, in this example I’ll assume it is available on a Windows PC as drive letter “E”.   To create your Garmin Custom Map follow these steps.

1. Move to a location on the Google Earth map where you want to download maps, for example: Walden Pond, Concord, MA.
2. Select GPS Visualizer Overlays under the Places window, right click and hit Refresh
3. If there is map data available for that location you should see a list of overlays available in the Places window under Garmin Custom Map Overlays.  Double click on the map layer (ie. USGS topo map) you would like to download.  This should start the Google Earth browser window on the GPS Visualizer page for the map image you selected.
4. If you want to use the default map name and Draw Order of 1 you can stop here and save the KMZ file to E:\Garmin\CustomMaps by selecting Click here to download your overlay and selecting Save!  You may need to create the CustomMaps directory if you don’t already have it.  If you would like to edit the name or Draw Order of your map select Click here to download your overlay and select Open.  A new overlay should show up in your Google Earth Places window,  like “USGS Topo map”.
5. Right click and select Properties on the overlay you created in the previous step.
6. Give your map a new name in the Name field, like Walden Pond Topo.
7. Select the Location tab and change the Draw Order field to 50 and click Ok.
8. Right click on the overlay in the Places menu and select Save Place As to save the KMZ file to E:\Garmin\CustomMaps (create the directory if you don’t already have it).

Here are some examples of  how these images look on my Oregon 550t.

Related posts:

1. Tips on Garmin Custom Maps — GPS Visualizer Adds Garmin KMZ Support
2. Tips on Garmin Custom Maps — Random Stuff
3. Tips on Garmin Custom Maps – Getting Started
4. Garmin Beta: Custom Raster Map Support for Oregon, Colorado and Dakota
5. Garmin Custom Maps Officially Available on Oregon, Dakota and Colorado