Garmin gets support for KML overlays — implications
Monday, October 12, 2009 (18:51 UTC) (I apologise - I believe this came from OgelEarth?)
Late last week Garmin came out with a beta update for its Colorado, Dakota and Oregon GPS devices that displays uploaded KMZ files containing geopositioned overlays. Garmin's announcement and instructions are here. This is the first time I am aware of that a mobile device renders KML overlays.
GPSTracklog covers the news, and has some usage tips. GPSFix has detailed instructions, tips on using GPS Visualizer's generated overlays, and an exhaustive list of tools and resources.
I happen to have an Garmin Oregon 300, and since I love it whenever a gadget I own gets better simply by aging, I did the (Windows only) upgrade and some testing myself this past weekend. The verdict:
1. Although it is beta, this is a very robust update — the KMZ overlay of satellite imagery from the likely underground nuclear processing plant in IRan blogged a few weeks ago works seamlessly. That's a 36 megapixel JPEG and a 16 megapixel JPEG in a 11MB combined KMZ file, into which I could zoom to see sub-meter objects! Screen refreshes are obviously not as rapid as on my MacBook Pro, but for a gadget meant to show a position in context it is plenty fast. I was expecting the file to completely bog down the Garmin, but the device didn't even blink.
2. Feed the Garmin a KMZ file with mixed KML-based objects, such as placemarks, polygons and overlays, and it wil ignore all the components except for the overlays. No complaining, no error messages. Just the overlays.
Some further thoughts:
1. In its instructions, Garmin writes in red ink:
However, please be responsible and only create a Garmin Custom Map from a map that is in the public domain, you hold the copyright in, or you have permission to use from the copyright holder.
I think that statement is a bit odd, and am not at all sure it is justifiable. I understand how the sharing or distribution of maps can require copyright permission, but that is the case for any map, online or offline, digital or paper. What I am having difficulty with in Garmin's statement is the attempt to parse a difference between owning a map and using a map. As far as I am concerned, owning a map but not being allowed to use it is a nonsensical demand.
To put it another way: Of course I should be able to scan a paper map I own, overlay it in Google Earth and import it into my Garmin. What's that got to do with the copyright owner?
Sharing the resulting file with an online community? Yes, that could require permission.
But it gets trickier: There are many, many thousands of map and imagery overlays accessible online as KMZ files. In all cases, they have been made available with the expectation that they be displayed on a screen attached to a computer. Until now, the application most likely doing the rendering will have been Google Earth (or possibly Google Maps, or Microsoft Bing), but that is by no means a limitation of the KML markup language. KML is an open standard, and any device is allowed to parse KML. Do any of these KMZ files come with the condition that they may only be viewed using some applications but not others, or may not be viewed in combination with other functionality, such as a GPS positioning function? I think not. So why would it be okay to view such files in Google Earth while running a GPS tracking tool, but not on a Garmin while running its GPS tracking function?
2. Why would anyone want to upload KMZ overlays to a Garmin in the first place? There is a very good reason, actually: No other portable device currently supports the display of KML overlays; Google Earth for the iPhone will likely get such support one day, but the iPhone is not an ideal GPS device, because it can only do one thing at a time, and tends to require a connection to the internet. If you're a nuclear weapons inspector headed for the hills outside Qum, this latest Garmin update is your friend.
Creating Garmin Custom Maps in Five Easy Steps
Step 1: Save the map in JPG format
Begin with the map you wish to use on your Garmin device. If in printed form, scan the image at an appropriate resolution (Oregon & Colorado have a native solution of 155 dpi). Garmin Custom Maps require the map be saved in JPG format. Since many maps are available in PDF, they may require conversion using GIMP or other suitable program.
Using Google Earth to georeference your map, begin by locating the approximate area on Earth where your Garmin Custom Map will be located. The closer the viewing window is to the location and coverage area of your JPG, the easier it will be to georeference. Once the location is set in Google Earth, use the menu to select “Add”, then select “Image Overlay”.
In the dialog box that follows, three important fields should be completed:
• Provide a meaningful Name.
• Set the Link field to the path of the source JPG to georeference.
• On the Location tab, Draw Order can be adjusted if desired. Draw order values less than 50 places the Garmin Custom Map below roads & trails, values 50 and greater places the Garmin Custom Map above most map features except points of interest & waypoints.
Before closing the New Image Overlay dialog box, you need to georeference the JPG. The most common way to do this is adjust the green marks to adjust the corners (a), edges (b), center (c), or rotation (d) of the JPG so it matches the satellite imagery beneath. It may be necessary to adjust the transparency (in the New Image Overlay dialog) to a level that allows adequate viewing of the JPG and imagery beneath. Once you are satisfied with the alignment of the source material, select “OK” on the New Image Overlay dialog box.
To send the newly created Garmin Custom Map to your Colorado, Oregon, or Dakota it should be saved to the device. To do this, right click on your Garmin Custom Map in the “Places” section on the left-hand side. From the popup menu, select “Save Place As”. Use the following dialog box to save your Garmin Custom Map to your Garmin handheld device, placing the file in the /Garmin/CustomMaps/ directory. Be sure to save the file in the KMZ format. If preferred, the file can be saved to a microSD card, in a /Garmin/CustomMaps/ directory for use with Garmin handhelds.
To discuss Garmin Custom Maps with others, please visit our Garmin Custom Maps developer forums.
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