The mobile computing landscape is witnessing an unprecedented number of devices that can acquire geo-tagged (aka location-based) data, for example, mobile phones, wearable sensors, in-vehicle dashcams, and IoT sensors. These devices can collect large amounts of data such as images, videos, movement parameters, or environmental measurements along with the data collectors' location data. However, we are giving away our location data to large Web search companies and social media companies for free. In addition, some of our smartphone apps gather our location data to sell to other companies for targeted advertising.
This data may be useful to third-party entities interested in gathering information from a certain location. For example, journalists may want to gather images around an event of interest for their newspaper; law enforcement may seek images taken soon before or after a crime occurred; and city authorities may be interested in travel patterns during heavy traffic.