Posts Tagged ‘geocorrelation’
Geotag Photos with Open GPS Tracker and digiKam
You don’t need a fancy camera with a built-in GPS receiver to geotag your photos. An Android device with the Open GPS Tracker app and digiKam can do the job just fine. The app lets you track your route and save it as a GPX file which you can then use to geocorrelate your photos in digiKam.
Geocorrelation is a relatively simple process which assigns geographical coordinates from the GPX file to the photos based on their time stamps. So for this technique to work its magic, you must sync the time on your Android device with your camera. When you head for a photo walk, launch Open GPS Tracker on your Android device and start a new tracking session. When you are back home, stop the tracking session, and use the Share Track button in Open GPS Tracker to save the recorded track in the GPX format on the SD card or send it via email to your machine.
Offload then the photos from your camera to digiKam, select them, and choose Image » Geolocation » Correlator. Press the Load GPX File button and select the GPX file. digiKam should then automatically assign geographical coordinates to the photos. By default, digiKam can tolerate a 30-second gap between the time settings of the camera and the GPX track. If the gap is longer, the application may fail to assign geographical coordinates to some of the photos. In this case, you can increase the time gap in the Max time gap field. Press then the Correlate button to refresh the geographical coordinates. This makes geocorrelation less precise, but you can use the Edit button to adjust the coordinates manually. Once you’re satisfied with the result, press the Apply button to save the assigned coordinates in the photos’ metadata, and you are done.
Geotagging Photos with digiKam
Even if your camera doesn’t support geotagging, you can easily add geographical coordinates to your photos using digiKam.
In digiKam, select the photo you want to geotag and choose Image -> Geolocation -> Edit Coordinates. This opens the Edit Geographical Coordinates window containing a map. Drag the map with the mouse and zoom on a specific area to locate the exact place where the photo was taken. Alternatively, you can use the Search field to enter the address, for example: botanic garden, berlin, germany. Hit then the Search button, and you should see a list of found places that are marked with pins on the map. To add geographical coordinates to the photo, click on the exact spot on the map to add a pin to the place where the photo was taken. You can then drag the pin with the mouse to adjust the pin’s position. Hit then OK, and you are done.
If you use a GPS device to record your track when shooting photos, you can use digiKam’s Correlator tool to geotag the images (mapping photos using a GPX file is often called geocorrelation). To do this, you have to export the recorded track from your GPS unit as a GPX file. In digiKam, select the photos you want to correlate, choose Image -> Geolocation -> Correlator, then press the Load GPX File button and select the GPX file. Hit then the Correlate button, and digiKam does the rest. Keep in mind that for this feature to work properly, the time on your GPS device and digital camera must be in sync. If the time on both devices differs, you can specify the time gap in the Difference in min[utes] field.
Once you’ve geotagged your photos, you can view them on the map without leaving the convenience of digiKam. To do this, click on the Geolocation sidebar to expand it, select the photo you want, and you should see it on the map. digiKam even lets you choose between different map providers, including Google Maps, OpenStreetMap, and MSN Maps. To switch to the desired map, choose it from the drop-down list at the bottom of the Geolocation sidebar.
Quick Notes
- digiKam can geotag photos in the JPEG and RAW formats.
- If your GPS device doesn’t support GPX format, you can use the GPS Babel tool to convert the device’s proprietary format to GPX.
- In the future, digiKam will support Marble and OpenStreetMap for offline geotagging.
- Nokia has recently opened their map web service API, so it’s possible that digiKam will provide support for Nokia maps in the future.
Thanks to Gilles Caulier for the comments.
