Hack 52. Show Your Waypoints on Aerial Photos with Terrabrowser

Show your waypoints over aerial photos and topographic maps on your Mac.

Terrabrowser is a Mac OS X program that lets you browse satellite photos and topo maps. It can show your current position on the map, as well as allow you to load and display waypoints in the GPX format. And like most fun tools, it has a few surprises to share. You can do some of the same things under Windows with Wissenbach Map3D [Hack #53] .

You can read more about Terrabrowser and download the program on their web page (http://www.chimoosoft.com/terrabrowser.html). The new alpha version uses Cocoa and supports tracklogs. But the old version is more stable and has better GPS support. Since both versions have interesting features, this hack will be clear about which version is being discussed.

Download the Terrabrowser 1.1.0.sit file and decompress it. Like most Mac OS X apps, you can run the program from that location or copy it into your Applications folder.

5.8.1. Live Tracking in Terrabrowser Version 1.1.0

Under Version 1.1.0, you can connect a Garmin GPS to your computer and have live tracking of your position over an aerial photo.

You may need to allow the program access to your serial ports:

$ sudo chmod 777 /dev/cu*

and then set your GPS to output data in NMEA format. Then in Terrabrowser, select the following menu options, as shown in Figure 5-5:

GPS->Protocol->NMEA,
GPS->Serial Port->usbserial0 
GPS->Connect (figure 1)
GPS->Enable Live Tracking

Figure 5-5. The Terrabrowser GPS Connection menu

An aerial photo should pop up with your current location shown. If you happen to be visiting me in Sebastopol, California, it will look identical to Figure 5-6; otherwise, you will see a photo of your location.

Figure 5-6. Terrabrowser live tracking

The new version provides additional information on the GPS status, but live tracking is not yet bug-free.

5.8.2. Using Terrabrowser to View and Edit Waypoints

In addition to live position tracking, Terrabrowser implements a very nice multifile GPX waypoint editor and viewer, shown in Figure 5-7. You can open multiple GPX files, edit waypoints, and copy and paste between waypoint files with a nice tabular interface. The waypoint editor also allows you full access to all the waypoint features, including a nice drop-down of waypoint symbols.

Figure 5-7. Terrabrowser waypoint display and editing

Another great feature is the ability to search by ZIP Code. Select Navigate images/ent/U2192.GIF border=0> Find City (or press -F) and you can enter a ZIP Code. Terrabrowser then fetches the appropriate image, centered vaguely on that ZIP Code. This is an imprecise process for two reasons. First, Terraserver returns images in "tiles," so when you request the image for a lat/long, you get the tile that contains that point, but it is not centered. Also ZIP Codes are not points, so converting a ZIP Code to a single point is a tad imprecise.

You can open a GPX-format waypoint file, and then select Waypointsimages/ent/U2192.GIF border=0>Center on Waypoint to fetch the Terraserver image, or USGS topo, for that point. In Figure 5-8, we centered on the waypoint "Box1."

Figure 5-8. Terrabrowser centered on waypoint "Box1"

Terrabrowser is shareware and well worth the $15 registration fee.