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Geocoding using iPhone reference photos

HoudahGeo offers several options for geocoding your photos: automatic using GPS track logs, using GPS waypoints, using built-in maps, using Google Earth, etc.

One of the lesser known options is geocoding from reference photos (aka. gap fill geocoding). The basic idea behind this technique is pretty simple. Your iPhone creates geocoded photos. You may however find the camera lacking when compared to your regular digital camera. Your preferred camera on the other hand lacks a GPS chip. HoudahGeo can match up geocoded photos from your iPhone with photos taken around the same time using your regular camera. It can thus assume both were taken at the same location.

This method does not require a dedicated track logger. It has the added advantage of giving you more control over your geotagged locations. You can attach all photos from a general location to the exact same GPS location. You can set a new location by simply taking a new photo with your iPhone.

The process is almost as simple as automatic geocoding using GPS track logs. Start by taking a geotagged photo using your iPhone. A random photo will do. Then shoot a series of photos using your digital camera(s). Repeat the procedure at the next location. This technique works best if both your iPhone and your regular camera are set to the same time.

Back at your Mac, 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: these lack geotags. Those from your iPhone will show geotags. 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.