Garmin Custom Map
It is easier than ever before to create custom maps for your Garmin Colorado, Oregon, or Dakota hand-held GPS. Following the five simple steps explained at the Garmin blog, I was able to create a GPS map of Callaway Gardens in just a few minutes. The result is a map displayed on my Garmin Oregon that looks the the same as the paper map patrons receive when visiting this family vacation resort.
Callaway Gardens
Callaway Gardens covers over 2,500 acres, including recreational lakes, hiking and biking trails, golf course, and of course - gardens. It is the kind of place you really need a map for getting around. While the paper map they give you at the entrance is good, having it on your GPS is a lot more fun.
in Five Easy Steps
Using the procedure found at the Garmin blog for "Creating Garmin Custom Maps in Five Easy Steps", it took more time getting the large paper map into Photoshop than it did to complete the rest of the procedure.
Step 1: Save the map in JPG format
I started with a paper map of Callaway Gardens. The paper map is 23-1/2" x 18" and my scanner is only 8-1/2 x 11" , so I had to scan multiple images and import them into Photoshop where I could stitch them back together. I used a scanner resolution of 150 pixels per inch which I have found be a good resolution for scanning paper maps for display on small screens. Once I had all the images stitched together in Photoshop, I was cropped it down to approximately 21" x 12", eliminating superfluous legends and borders. In terms of pixels, the map is now 3132 pixels x 1800 pixels and the file size is about 2 MB. Given the scale of the paper map, each pixel corresponds to about 6 feet on the ground or about a 3.5 miles x 2 mile area.
Hint: Save the map image in baseline "standard" .jpg format. Do not save the image in a "progressive" .jpg format. If you save in a progressive format your GPS will report an error and you will have to start all over.
Step 2: Create an Image Overlay
Creating an image overly in Google Earth is a straight forward procedure. More information on the image overlay feature in Google Earth can be found at the Google Earth User Guide.
Hint: The trick here is to start with the view in Google Earth covering an area a little larger than the area covered by your map.
Step 3: Link the JPG
During this step remember to click on the Location tab and set the draw order value. I suggest a draw order value greater than 50 just to keep your custom map from hiding under other map layers. You can tweak this later if desired.
Step 5: Adjust the Boundaries
Most of the time you spend on this step will be getting the image to line up exactly with the satellite image. At some point you will realize that perfection is not obtainable and you will settle for the best alignment you can achieve with all things considered.
Hint: Adjust the opacity of the overlay to see the satellite image under the overlay.
Step 5: Send to Garmin
Here I need to insert a couple of steps into Garmin's procedure.
5a) Update your GPS using WebUpdater
5b) Browse the Garmin directory on your GPS and create "CustomMaps" sub-directory if one does not already exist.
Now, you can send your custom map to your GPS by saving your image overlay in Google Earth as a .kmz file in your /Garmin/CustomMaps/ directory.
Viewing your Custom Map
If you have done everything correctly, you will be rewarded by seeing your custom map displayed on your GPS. By default your GPS settings are enabled to view custom maps. This setting can be disabled from the Map Info screen (shown at right).
If you do not at first see your custom map, keep zooming in. My map started showing up at the .3 miles scale.
Conclusion
Custom maps of the size and scale of the Callaway Gardens map work well in the Oregon. Larger maps may bog down the computing resources and smaller maps may not be big enough to be useful. Other example maps that reportedly work well are: maps of college campuses, amusement parks, golf course, battelfields...
If you would like to download this example GPS Map of Callaway Gardens, click here.
For more information about Callaway Gardens click here.
If you have an interesting application for custom maps, contact me, I'd like to hear about it.
