A Multi-player Online Game for Semantic Annotation Hernisa Kacorri PhotoSlap

what

why Photo Metadata People: Who are in the picture? Objects: What objects are in the picture? Event: What was the event? manually annotating  Tedious and time-consuming  Need for incentives:  monetary rewards  promoting a common good  fun Time: When was the photo taken? Location: Where was the picture taken? automatic annotation  Embedded metadata in standard JPEG format (EXIF)  time  resolution  ISO  aperture  shutter speed  GPS-equipped devices  location

related work Automatic Image Annotation requires:  Training the annotation system  Analyzing and transforming training images into feature vectors  Capturing relationships by probabilistic models: Human Computation examples:  Label Me: web-based image annotation tool  Riya: visual search engine (combines manual labeling & machine learning)  ESP Game: interactive game in which a player attempts to label a given image presented by the system to match any label given by his online partner within a predefined time limit.

game mechanism Game Actions  Flip  Slap  Object  Trap Scoring Mechanism  A player gets points : – First to slap without drawing any objection. – First to object without falling into a trap. – Another player slaps on the trap he/she sets.  A player loses points: – First to object and fall into the trap. – No player slaps on the trap he/she sets.

game strategy analysis The target strategy Game tree of the trap stage Game tree of the game stage the expected payoff for player 3: P trap (- S trapped ) + (1 - P trap ) S object player 3 should object if: P trap < S object / (S object + S trapped ) Subgame

subgame perfect equilibrium action of Player 1 action of Player 2 Action of Player 3 depends on his/her belief about depends on his/her belief about depends on his/her belief about

gameplay gameplay is all the activities and strategies game designers employ to get and keep players engaged (Prensky 2002) that promote deep and persistent engagement.  The core elements of gameplay in PhotoSlap are:  Pattern-recognition challenge  Reaction time challenge  PhotoSlap is designed to be self-adaptive in that the competitors are carefully chosen so that the difficulty of challenges, the competitors’ reaction time, and their ability can be balanced to enable them to stay in the flow state.  The appearance of a matching pair is dynamically adjusted to follow a tension curve that has proper frequent peaks [ p(t) = N e ^(gt) ].

system overview

evaluation Is the game fun? PhotoSlap received an average score of 7.6 points on a 10-point scale. How good is the game strategy? Is the game productive? productivity of the game: is measured by the links being built and the percentage of the correct links. each game can produce 12.3 links per minute and 98.31% of them are correct.

do you want more ? Paparas, D. 2008; Εγωιστική Απόθεση Φορτίου υπό συνθήκες Μερικής Γνώσης. Τμήμα Πληροφορικής και Τηλεπικοινωνιών ΕΚΠΑ von Ahn, L., and Dabbish, L. 2004; Labeling images with a computer game. In Proc. CHI ’04, 319–326. ACMPress. Ting-hsiang Huang Jane Yung-jen Hsu; Beyond Memories: Weaving Photos into Personal Social Networks