world explorer (jcdl 2007 best paper)
DESCRIPTION
Slides from my presentation at JCDL 2007. The paper was titled "World Explorer: Visualizing Aggregate Data from Unstructured Text in Geo-Referenced Collections" and won the Vannevar Bush Best Paper award. You can read the full paper at http://www.rahulnair.net/files/JCDL07-ahern-WorldExplorer.pdf and also see a demo at http://tagmaps.research.yahoo.com/worldexplorer.phpTRANSCRIPT
1yahooresearchberkeley.comRahul Nair - World Explorer
World Explorer: Visualizing Aggregate Data from Unstructured Text in Geo-
Referenced Collections
Shane Ahern, Mor Naaman, Rahul Nair* & Jeannie Yang
Yahoo! Research Berkeley
2yahooresearchberkeley.comRahul Nair - World Explorer
Attraction Map of Paris
Stanley Milgram, 1976. Psychological Maps of Paris
3yahooresearchberkeley.comRahul Nair - World Explorer
Attraction Map of Paris
Y!RB, 2007.
4yahooresearchberkeley.comRahul Nair - World Explorer
Flickr “geotagged”
20+ million images
Can we do better?
5yahooresearchberkeley.comRahul Nair - World Explorer
Location-driven Modeling
• Derive meaningful data about map regions
• E.g., representative tags, photos
6yahooresearchberkeley.comRahul Nair - World Explorer
Data Description
7yahooresearchberkeley.comRahul Nair - World Explorer
Issues
• Sparse data set• Photographer bias
– In location– In tags
• Incorrect data
8yahooresearchberkeley.comRahul Nair - World Explorer
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
9yahooresearchberkeley.comRahul Nair - World Explorer
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)|
10yahooresearchberkeley.comRahul Nair - World Explorer
Scoring
• Score (t) = TF * IDF * UF• Threshold values
– 30+ photographs – Minimum 3 users– Score > 1
• Final dataset: (tag, score, latitude, longitude)
11
DEMO
12yahooresearchberkeley.comRahul Nair - World Explorer
Precomputation
• Divide the world into equal sized non-overlapping tiles
• Compute and store the tags for each tile
• Repeat for different zoom levels
13yahooresearchberkeley.comRahul Nair - World Explorer
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
14yahooresearchberkeley.comRahul Nair - World Explorer
User Study
10 subjects• 6 female, 4 male• Ages 20-60• Varying technical knowledge• No geotagged photos of their own
15yahooresearchberkeley.comRahul Nair - World Explorer
Experiment tasks
• Vacation recap• San Francisco tour• Explore a new city
16yahooresearchberkeley.comRahul Nair - World Explorer
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"
17yahooresearchberkeley.comRahul Nair - World Explorer
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”
18yahooresearchberkeley.comRahul Nair - World Explorer
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”
19yahooresearchberkeley.comRahul Nair - World Explorer
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
20yahooresearchberkeley.comRahul Nair - World Explorer
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
21yahooresearchberkeley.comRahul Nair - World Explorer
Future work
• Adding search capability• Show photos in places with no tags• Differentiate locations and events• Apply to other types of georeferenced
data
22yahooresearchberkeley.comRahul Nair - World Explorer
tagmaps.research.yahoo.com
• World Explorer• Data API• Visualization toolkit
• Trip Explorer• Night Explorer