World Explorer (JCDL 2007 Best Paper)

Slide 1: World Explorer: Visualizing Aggregate Data from Unstructured Text in Geo- Referenced Collections Shane Ahern, Mor Naaman, Rahul Nair* & Jeannie Yang Yahoo! Research Berkeley Rahul Nair - World Explorer yahooresearchberkeley.com 1

Slide 2: Attraction Map of Paris Stanley Milgram, 1976. Psychological Maps of Paris Rahul Nair - World Explorer yahooresearchberkeley.com 2

Slide 3: Attraction Map of Paris Y!RB, 2007. Rahul Nair - World Explorer yahooresearchberkeley.com 3

Slide 4: Flickr “geotagged” 20+ million images Can we do better? Rahul Nair - World Explorer yahooresearchberkeley.com 4

Slide 5: Location-driven Modeling • Derive meaningful data about map regions • E.g., representative tags, photos Rahul Nair - World Explorer yahooresearchberkeley.com 5

Slide 6: Data Description Rahul Nair - World Explorer yahooresearchberkeley.com 6

Slide 7: Issues • Sparse data set • Photographer bias – In location – In tags • Incorrect data Rahul Nair - World Explorer yahooresearchberkeley.com 7

Slide 8: Heuristics • Number of photographs denotes the “importance” of a location • Users will use a common subset of tags to describe objects/locations • Concentrated tag usage indicates descriptiveness Rahul Nair - World Explorer yahooresearchberkeley.com 8

Slide 9: Algorithm • Clustering: k-Means, get set of k clusters • “Document” C is bag of all tags in cluster • For each tag in C calculate: – TF = |P(C,t)| – IDF = |P(R)| / |P(R, t)| – UF = |U(C,t)|/|U(C)| Rahul Nair - World Explorer yahooresearchberkeley.com 9

Slide 10: Scoring • Score (t) = TF * IDF * UF • Threshold values – 30+ photographs – Minimum 3 users – Score > 1 • Final dataset: (tag, score, latitude, longitude) Rahul Nair - World Explorer yahooresearchberkeley.com 10

Slide 11: DEMO 11

Slide 12: Precomputation • Divide the world into equal sized non- overlapping tiles • Compute and store the tags for each tile • Repeat for different zoom levels Rahul Nair - World Explorer yahooresearchberkeley.com 12

Slide 13: Retrieval • Find the tile level closest in size to the request area • Select the tiles that fully cover the request area • Return the tags that fall within the request area Rahul Nair - World Explorer yahooresearchberkeley.com 13

Slide 14: User Study 10 subjects • 6 female, 4 male • Ages 20-60 • Varying technical knowledge • No geotagged photos of their own Rahul Nair - World Explorer yahooresearchberkeley.com 14

Slide 15: Experiment tasks • Vacation recap • San Francisco tour • Explore a new city Rahul Nair - World Explorer yahooresearchberkeley.com 15

Slide 16: Recall Reminded the subject about locations • “It brings out memories” • “Oh my God! This place has the best restaurants” • “We wanted to see the Polynesian Cultural Center\" Rahul Nair - World Explorer yahooresearchberkeley.com 16

Slide 17: Discovery Participants discovered previously unknown locations and events – “I’ve never heard of this festival” – “There is car racing which I'd probably go see” Rahul Nair - World Explorer yahooresearchberkeley.com 17

Slide 18: Needle & Haystack • Excellent visualization of the Haystack • Hard to find specific information – “Where was Culver City again?” • No way to search – “I guess what I’m looking for are bull fighting pictures” Rahul Nair - World Explorer yahooresearchberkeley.com 18

Slide 19: Other Responses • Gets the “vibe” of a place • Share with other people • Tags did not always match the mental model of a location • Wanted more tags • Want more info about tags Rahul Nair - World Explorer yahooresearchberkeley.com 19

Slide 20: Conclusions • Extracted meaningful aggregate information from georeferenced data • Allows users to explore locations in a new way • Users like using the overview but also want the ability to search Rahul Nair - World Explorer yahooresearchberkeley.com 20

Slide 21: Future work • Adding search capability • Show photos in places with no tags • Differentiate locations and events • Apply to other types of georeferenced data Rahul Nair - World Explorer yahooresearchberkeley.com 21

Slide 22: tagmaps.research.yahoo.com • World Explorer • Data API • Visualization toolkit • Trip Explorer • Night Explorer Rahul Nair - World Explorer yahooresearchberkeley.com 22

Slide 23: Questions? Rahul Nair rnair@yahoo-inc.com http://tagmaps.research.yahoo.com 23