HoudahGeo has traditionally offered several methods of geocoding photos: automatic, manual, bookmark,…. HoudahGeo 2.4 adds a new method: geocode from reference photos.
The most convenient method of geocoding usually is automatic geocoding using a track log. Track logs are created by GPS devices which periodically record current position and time. HoudahGeo will match up times in the track log with the timestamps on the photos. iPhone 3G users may use applications like Trails or GPSRecorder to turn their iPhone into a track recorder.
There are however situations where one would like to have more precise control over the geotags. There are also situations where iPhone track logging is not practical. HoudahGeo 2.4 now offers an alternative to continuous track logging: gap fill geocoding. Photographers may now attach all photos form a shoot to a single location, rather than having the photos track minute movements and GPS precision flukes.
The basic idea behind this new technique is pretty simple. Your iPhone creates geocoded photos. However the quality of those photos is low. Your digital camera is able to take excellent pictures. But it lacks a GPS chip. Gap fill geocoding will match up geocoded photos with your iPhone with photos taken around the same time using your real camera. It can thus assume both were taken at the same location.
All you need to do, is use your iPhone to take a picture at each location where you are shooting using your regular camera. All that is needed, is a random snapshot taken shortly before or after making the photos you want to be geocoded.
Back at your computer you load both the images from your camera and those from your iPhone into a HoudahGeo project. The images from your camera will be listed in red: they lack geotags. Those from your iPhone will show geotags.
Now select "Geocode from Reference Photos…" from the "Geocode" menu. HoudahGeo will work its magic to geocode the photos from your camera to the locations of nearby iPhone photos.