Mapping Hacks

Show Your Waypoints on Aerial Photos with Terrabrowser #52

Chapter 5, Mapping with Gadgets

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HACK

Then we create a GPSBabel arc filter file from a tracklog:

$ gpsbabel -i gpx -f track.gpx -o arc -F arcfile.txt

Then we apply the arc filter to include only those waypoints that are within

one mile of that track:

$ gpsbabel -i gpx -f allwaypoints.gpx -x arc,file=arcfile.txt,distance=1M | wc

61 322 3022

So 61 of our waypoints were within one mile of the path described in track.gpx.

This is interesting because as you fill your waypoint memory with points, it

is easy to forget where those points are. When I ran this arc filter test, I was

surprised when my waypoint “PEACE” appeared. I was sure that was the

Peace Dive boat in Ventura, California. So I explored:

$ gpsbabel -i gpx -f allwaypoints.gpx | grep -i PEA

38.403327N 122.847930W PEACE /CRTD 15:52 15-SEP-00

34.241402N 119.263898W PEACEB/CRTD 17:25 16-OCT-01

Ah! Now I remember! “PEACE” is the Peace Park near my house. It was cer-

tainly within one mile of the track in the filter example. The Peace Dive boat

was “PEACEB,” for “Peace Boat.” This sort of name collision is inevitable

when you start seriously hoarding waypoints in a device with a six-charac-

ter limit on names! Tools such as GPSBabel filters can help make some sense

out of the whole mess.

HACK

#52

Show Your Waypoints on Aerial Photos with

Terrabrowser Hack #52

Show your waypoints over aerial ...