Image: Game
 Northwestern University
The "Ghost Hunter" game helps researchers gather thorough pictures from all angles of a building, for mapping.
updated 3/18/2012 3:52:38 PM ET 2012-03-18T19:52:38

With all the pictures people have posted on photo-sharing websites such as Flickr, someone could almost build a map of all the structures in the world. Almost, but not quite. Some places are far more popular in photos (the Statue of Liberty) than others (the laundromat). People also tend to take pictures of the front of buildings and monuments.  "Flickr has thousands of photos of the front of the Lincoln Memorial," Fabian Bustamante, an engineer at Northwestern University, said in a statement. "But who takes a picture of the back? Very few people."

So Bustamante developed an Android game called Ghost Hunter. Players get a map of their neighborhood with ghosts shown on it. They track a ghost until they get close, when the map will switch to an augmented reality screen that shows a video stream of the surroundings with arrows pointing toward where the ghost is. Players follow the arrows until they get the ghost in their crosshairs, then zap! Each zapped ghost earns them points.  And as they're zapping, the phone actually takes a photo of the place. 

In this way, Bustamante got pictures all around the Charles Deering Library on Northwestern's campus. He compared those photos with photos of Deering Library on Flickr and found that Flickr photos were much more concentrated at the front of the building. 

He also adjusted the game and got it to capture noise in the locations where players zapped ghosts. He got data from a larger area of Northwestern University compared to another application he made that asked people to record noise as they walked around Northwestern University in their daily lives.  

He calls the program, which convinces people to gather the data scientists want by making it into a game, "soft control" of crowds. Such "soft control" games could also encourage people to go to unusual places and collect data about air quality, traffic or anything else researchers want to study, Bustamante wrote in a paper he presented February 28 at the HotMobile conference for mobile apps.  

The data Ghost Hunter gathers is rendered anonymous before researchers get it, Bustamante wrote in his paper. The game doesn't ask players to give up more private information than other location-based apps, such as Foursquare and Gowalla. It could potentially lure people into unsafe places, so it depends on the player's own judgment about whether to follow ghosts. If Ghost Hunter and similar games were widely used in the future to help scientists gather data, they will have to tell players that's what they're doing, Bustamante said. 

© 2012 All rights reserved. More from


Discussion comments


Most active discussions

  1. votes comments
  2. votes comments
  3. votes comments
  4. votes comments