Owners of the Garmin Colorado, Dakota and Oregon series got a nice surprise yesterday, when the company rolled out the ability to create a custom map image in Google Earth, opening the door to viewing aerial photos, USGS topos and park maps on your GPS.
I immediately downloaded a US Forest Service topo (which often have greater FS road detail than USGS topos), transferred a portion to my Oregon, and hit the trail. You can see the results in the image to the left.
Accuracy is completely related to how well you georeference the image, but I was pretty pleased with the results. The red line is a track of the trail created by someone else, so I can’t vouch for the accuracy of that, but my own track lined up well with the USFS trail on the map, and had me on the proper side of the creek, so I was pretty pleased with my first attempt. I’ll also note that the Oregon was in a mesh pocket on the back of my pack, not the ideal spot for reception. Admittedly, I wasn’t going that fast (15 MPH tops), but I noticed no problems with redraws. Others are reporting sluggish behavior for larger mapsets.
Tips for making custom Garmin maps
- Use a DrawOrder of 50+ to keep the custom map on top of other imagery, as I did above. You’ll still be able to see waypoints, tracks, POIs, etc. This is ideal for topo maps.
- Use a DrawOrder of less than 50 and contour lines, roads and depth contours present on the underlying Garmin map will show through. This may be better for park maps, marine charts and aerial photos.
- This site has links for free raster imagery for each of the 50 United States. DRGs are topo maps, DOQQs are aerial photos. This is an older page, but enough links work to make it worth sharing.
- If you need to convert from a particular file type to a .jpg (and don’t have software for it), search for an online file conversion service, or learn to use GIMP.
- Scott at GPSFix had a great tips post yesterday, and has promised another today.
Custom Garmin map discussion threads
We’re all still learning about the process and limitations of this new tool. There are active discussions going on in the following forums:
- Garmin has their own custom map forum
- Custom map thread on gpsfiledepot.com
- Groundspeak forum discussion on custom raster maps
More to come
Stay tuned. Over the next few days I’m expecting a lot of sharing of custom maps (this is already being done on the Garmin forum), tools for converting geo-referenced maps (eliminating the need to do this by hand), and information on using sources of .kmz files with images already posted online. Maybe some of you Google Earth ninjas can enlighten us on the latter in the comments section. And how about the rest of you? Have you tried this? How is it going?