Last Known Location

The beauty of photos taken with a phone is they are automatically geo-tagged. I love geo-tagging, as with every photo I can pull up the map location, search and organize photos by locations etc.

Adding locations to DSLR photos was difficult. It typically required an awkward piece of equipment (a dedicated GPS receiver) attached. It was slow and drained batteries quickly. Then came the idea of the phone keeping a timestamped GPS log and synchronizing locations based on the camera clock (which I was often forgetting to adjust). Now with phones it is all built-in.

But the issue with location stamping is the location data is not always available. It takes from a couple of seconds to couple of minutes to get a GPS "location fix". Which is the time the GPS receiver needs to collect the data from multiple satellites. Sometimes this is not possible at all. One example is flying a Boeing 787 "Dreamliner" which has electronic window shades which block the radio waves entirely and no consumer GPS equipment works aboard that plane. Planes with "normal" windows are fine - a GPS fix can be obtained fairly quickly, but that is still a matter of about a minute (a plane is moving fast so it involves acquiring more GPS data points until the fix is reliable.

iPhones have some peculiar behavior when they do not have the location fix. They seem to be applying the "last known" location to the photos when GPS data is not available. Which leads to significant errors - like the one on the attached image. The photo taken on the approach to Montreal (YUL) was tagged as taken at Munich airport (MUC), some 6000 kilometers away. This is a big error. Now - fortunately - the location data can be manually changed (albeit not using a map interface - this is a fairly recent improvements in the Photos app. But still the phione does not tell you in any way it was not sure about the location. So probably very few people will notice the error.