This document discusses methods for automatically extracting event and place semantics from tags associated with geotagged photos posted to Flickr. The authors propose an extended data model to associate tags with locations and times. They then evaluate three methods - naive scan, spatial scan statistics, and a scale-structure method - for identifying tags that exhibit significant time- or place-based patterns that could indicate events or locations. An experiment on a dataset of photos from San Francisco analyzes the performance of these methods by comparing their precision and recall against a ground truth.

1. Tye Rattenbury, Nathan Good, Mor Naaman* Yahoo! Research Berkeley (Yahoo! Advanced Development Division) Towards Automatic Extraction of Event and Place Semantics from Flickr Tags

3. Find the Differences “ Yahoo! Headquarters” “ Dog” “ SIGIR 2007”

4. Data Description

5. Simple Model (photo_id, user_id, time, latitude, longitude) (photo_id, tag)

7. Tag Maps - San Francisco

11. Extended Model (photo_id, user_id, time, latitude, longitude) (photo_id, tag) (tag, location) (tag, time)

12. Tag Patterns

13. Tag Patterns

14. Tag Patterns

20. Naïve Scan

21. Spatial Scan

24. Scale-structure Identification

25. Scale-structure Identification Entropy = 1.421621 Entropy = 0.766263 Entropy = 0.555915 Entropy = 0.062760 “Barry Bonds” tag

27. Experiments byobw Ground Truth: BYOBW?

29. The Obligatory Slide Where I Show You that Our Curve is Above the Other Curves

30. Experiments

33. Tag Maps - Paris - Les Blogs?