Using WPS to determine location
Eye-Fi cards use Wi-Fi Positioning System (WPS) for geotagging purposes. While similar, WPS is not the same as Global Positioning System (GPS), which is used in most location devices. WPS uses surrounding wireless networks to triangulate the location where the photo was taken, unlike GPS, which uses satellites.
Many things must happen for the latitude and longitude to end up in the EXIF data of a photo. First, a camera captures the photo. An Eye-Fi card detects any Wi-Fi networks in the area and records the MAC addresses of each one while not actually connecting to them. The MAC addresses are stored in the Eye-Fi card with the picture until it uploads the photo. Once the Eye-Fi card comes into contact with a configured wireless network and the photos begin transferring, the WPS data is sent to the Skyhook WPS service. At that time, the Skyhook WPS service translates and triangulates the WPS data to determine latitude and longitude. Skyhook then sends this information back to Eye-Fi's servers, which write the latitude and longitude to the photographs EXIF. At this point, the photo is delivered in its entirety to your computer or online photo sharing web site.
Improving Geotagging frequency and accuracy
If you are in an area that is sparsely populated or has a minimal amount of wireless networks, your photos won't necessarily geotag. An Eye-Fi card must be in range of a wireless access point that is in the Skyhook WPS database before it can provide a location. Here are a few things that you can do in order to improve geotagging performance:
- If you are able to find the MAC address of a nearby network that is not geotagging (or geotagging incorrectly), you can add the network's physical address to Skyhook Wireless's database.
- Add your home's wireless network to the Skyhook database. Please note that it can take up to 6 weeks for your submission to appear.
- If you want to check if you are in a mapped area, locally or abroad, you can visit Skyhook's web site for a coverage map.
- Give your Eye-Fi card time to "catch" an access point. Quickly turning the camera on and off conserves battery power, but it also limits the time your camera has to find extraneous WiFi signals. Keeping your camera powered on longer before and after a shot increases the chances for "catching" an access point signal.
Geotagging on mobile devices:
If your mobile device is set to automatically upload images that it receives from an Eye-Fi card, the Eye-Fi servers or Eye-Fi Helper software will attempt to geotag a photo before delivering it to your computer. However, if you manually share the image later there will not be any geo data because the images on your phone or tablet will not be geotagged.