GPSdings - a java GPS toolbox

gpsdings usage example: a mountain hike in the Alps

You can download the complete example for both bash and Windows cmd.exe. We will use cmd.exe syntax here.

Unix: If you use gpsdings frequently you can define an alias for gpsdings in your .bashrc or equivalent configuration file

alias gpsdings='java -jar /absolute/path/to/gpsdings.jar'

This will allow you to invoke gpsdings from any working directory by simply typing gpsdings.

Before the trip

We load the digital topographical map Austria West into the EADS-GeoGrid-Viewer that comes with the German Top 50 maps, and draw our planned trip. We save it as an ASCII overlay file guffertrunde-planned.ovl (the file available here is in fact not derived from a map but from GPS data recorded by the author, so its publication does not infringe anyone's copyright).
We convert the ovl file to gpx with
```
java -jar gpsdings.jar gpxovl guffertrunde-planned.ovl
```
and obtain the file guffertrunde-planned.gpx.

We can enrich the gpx file with SRTM elevation data

java -jar gpsdings.jar elevations ^
  --todir . ^
  --Trkpt ^
  --Wpt ^
  guffertrunde-planned.gpx

and create an altitude profile

java -jar gpsdings.jar trackanalyzer ^
  --plot "DistanceTravelled|Elevation|graph0.svg|Guffertrunde (planned)" ^
  guffertrunde-planned.gpx

We load the GPX file into gpsbabel or GPS Trackmaker and copy the planned track into the memory of the gps receiver. With the Garmin Geko 201, for example, you have two options: if you copy the track into the active log of the receiver it will show up on the map page of the receiver as a breadcrumb trail. If you copy it into one of the saved track slots (these have some limitations) you can follow it using TracBack^® (see p. 18 of the owner's manual). In either case you should make sure that the whole planned track has been copied to the receiver by transferring it back to the computer and comparing it to the original.

During the trip

We synchronize the clock of our digital camera to the GPS time. We are in time zone UTC+002 (CEST). This corresponds to an UTC offset of 2 × 60 × 60 = 7200 seconds.
We follow the planned track, which is displayed in the map page of the gps receiver.
We let the GPS receiver record our track. From time to time we take a picture with our camera, and we mark some waypoints at special locations like the summit.

After the trip

We download the recorded track from the receiver and save it as GPX 1.1 with gpsbabel or GPS Trackmaker.
(Optional) We delete the hand-drawn track segment from the gpx file in a text or xml editor. We can recognize it from the fact that its track points all have the same time stamp or no time information at all.
We also remove track points with large errors that were recorded when the receiver had poor sky view, and we add some meta-information. The result is guffertrunde.gpx.
We let gpsdings create a Google Earth kmz file with nice waypoint symbols:
```
java -jar gpsdings.jar gpxkml ^
  --kmz ^
  --name Guffertrunde ^
  guffertrunde.gpx
```
The result is guffertrunde.kmz
We download the digital camera pictures and put them in a folder called photos-original.
Now we create copies of the photographs in the folder photos that have the geo-coordinates of the locations where they were taken in their XMP file headers (--XMP). The geo-coordinates are also written over the lower part of the images (--stamp). Additionally, a semi-transparent track view, in which the place the photograph was taken is marked by a red dot, is added to the upper right corner of each image (--Track).
```
java -jar gpsdings.jar exifloc ^
  --utc-offset 7200 ^
  --copy-to photos ^
  --gpx guffertrunde.gpx ^
  --XMP ^
  --stamp @mypattern.html S 0.8 ^
  --Track NE 0.25 #7fffffff #00ffffff RED ^
  photos-original\*.jpg
```
We now copy the GPS information from the XMP header to the Exif header. Since we read the gps information from the XMP header with --read-gps-tag --xmp we do not need to specify a UTC offset and a GPX file to read from.
```
java -jar gpsdings.jar exifloc ^
  --read-gps-tag --xmp ^
  --Exif  ^
  photos\*.jpg
```
Then, we create a Google Earth photo KMZ file, a JavaScript file and a GPX file with waypoints for the photographs. This time we read the gps information from the Exif file header.
```
java -jar gpsdings.jar exifloc ^
  --read-gps-tag ^
  --kmz guffertrunde-photos.kmz --image-size 200 200 ^
  --javascript guffert-photos.js ^
  --GPX guffertrunde-photos.gpx ^
  photos\*.jpg
```
The KMZ result is guffertrunde-photos.kmz. It contains copies of our digital camera pictures that are scaled down so that they fit into a 200 px × 200 px square.

Now, we visualize the GPS data as an OpenLayers slippy map.

First, we create a color-coded elevation kml file with trackanalyzer.
```
java -jar gpsdings.jar trackanalyzer ^
  --kml "Elevation|elevation.kml" ^
  guffertrunde.gpx
```
We will include this kml file in the visualization using the openlayers --kml option.
We use shrink to reduce the total number of trackpoints to 100.

java -jar gpsdings.jar shrink ^
  --numpoints 100 ^
  guffertrunde.gpx ^
  > guffertrunde-n100.gpx

We are now ready to make the map. With the --photojs option we include the JavaScript output of exifloc, above.

 java -jar gpsdings.jar openlayers ^
  --javascript omap.js ^
  --Javascript-URL omap.js ^
  --Photo-URL photos/ ^
  --base-layers "OSMMapnik OSMCyclemap" ^
  --xhtml omap.html ^
  --kml-URLs elevation.kml ^
  --photojs guffert-photos.js ^
  guffertrunde-n100.gpx

Finally, we make gpsdings plot some graphs:

java -jar gpsdings.jar trackanalyzer ^
  --plot "TimeTravelled|DistanceTravelled|graph1.svg|Guffertrunde" ^
  guffertrunde.gpx
java -jar gpsdings.jar trackanalyzer ^
  --plot "DistanceTravelled|Elevation|graph2.svg|Guffertrunde" ^
  guffertrunde.gpx
java -jar gpsdings.jar trackanalyzer ^
  --smoothing=5 ^
  --plot "TimeTravelled|VerticalSpeed|graph3.svg|Guffertrunde" ^
  guffertrunde.gpx

The result is graph1.svg, graph2.svg, graph3.svg.