Using WPS to determine location

Eye-Fi Cards use Wi-Fi Positioning System from Skyhook Wireless, or WPS, for geotagging purposes. WPS while similar is not the same as the Global Positioning System, or GPS, that is used in most location devices. WPS uses surrounding wireless networks instead of satellites to triangulate the location where the photo was taken. After the photo is taken, many things must happen for the latitude and longitude to end up in the EXIF data of the picture.

First, the photo is taken. The Eye-Fi Card detects that there are many Wi-Fi networks in the area and records the MAC addresses of them all, while not actually connecting to them. Those MAC addresses are stored in the Eye-Fi Card with the picture until the photo is ready to be uploaded. Once the Eye-Fi Card comes into contact with a configured wireless network and the photos begin transferring the WPS data are sent to Skyhook Wireless. At that time, Skyhook Wireless translates and triangulates the WPS data, creating a latitude and longitude. Skyhook Wireless then sends that information back to the photograph where the Eye-Fi Server writes the latitude and longitude to the EXIF. At this point, the photo is delivered in its entirety to your computer and/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 the photos won’t necessarily geotag. An Eye-Fi Card must be in range of a wireless access point that is in the skyhook database before it can provide a location. There are a few things that you can do in order to improve your geotagging performance.

1. If you are able to find the MAC address of a nearby network that is not geotagging, you can add the network’s physical address to Skyhook Wireless’ database.
2. Add your home’s wireless network to the database using the link from #1 above. Please note that it can take up to 6 weeks for your submission to appear.
3. 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.
4. Give your Eye-Fi Card time to “catch” an access point. Quickly turning the camera on and off will help conserve battery power but it also limits the time avaialible to find extraneous WiFi signals. Staying on longer before and after a shot increaeses the chanches for “catching” an access point signal.