Yannis Tzitzikas FORTH-ICS

1. Improved Catalogue Searching and Browsing Approach: Dynamic Taxonomies and Faceted Search for ESA Products Yannis Tzitzikas FORTH-ICS USNG User Workshop

2. Outline • Motivation • Some results from Requirements Analysis • Proposed Approach • Facet-based Indexing and Exploration for EO Catalog • Facet Analysis for ESA • Demonstrators/Technical Feasibility • FleXplorer (and its application on a Web Search Engine) • Experimental Results • Concluding Remarks USNG User Workshop

3. Users want an easy to use service Intuitive Functional search facility Accurate and up to date information Online availability of data Browse Imagery All images (ESA and non ESA) Users can select the data indicating the type and quality of information required (e.g. resolution/bands/semantics), rather than specifying the details (e.g. satellite/sensor/mode) What does this implies: Features Extraction at ingestion Catalogue metadata extension Ontology and semantic engines Some Results (excerpts) from the Requirements Analysis(ref: URR March 18, 2008 ) USNG User Workshop

4. Facet-based Indexing and Exploration • Traditional research has focused on retrieval of information but the most common task is exploration • Examples • Buying a digital camera • Finding a job • Selecting a photo (to include in your web page) • Finding a hotel • For instance, to select a hotel, I would first like to see an overview of the available choices. I want to be sure that there is not any better one than the one that I am about to select (the notion of better is very vague: I may not know all attributes, may there is not even a fixed attribute set). USNG User Workshop

5. Facet-based Indexing and Exploration In general, we could say that • Query services are either • too simplistic (e.g. free text queries in IR systems or Web search engines), or • too sophisticated (e.g. SQL queries, or Semantic Web Queries). • Browsing is either • too simplistic (e.g. plain Web links) or • very application specific (dynamic pages derived by specific application programs). Information Exploration services could bridge this gap and provide effective and efficient general purpose access services. Below we will discuss the case of facet-based indexing and exploration USNG User Workshop

6. Examples: Bibliography Searching/Browsing Zoom-In points USNG User Workshop

7. (cont) After selecting Acta Inf from Refine by VENUE New (refined) focus/answer set New Zoom-In points USNG User Workshop

8. Other related Examples: google base (see http://base.google.com/) USNG User Workshop

9. (cont) When you select a value in one field, in the rest fields you see only those values that if selected would not yield an empty answer USNG User Workshop

10. Advantages of this interaction model • The user is effectively guided to reach his goal: • at each stage he has a complete list of all related terms (i.e. a complete taxonomic summary of his current focus) • No empty results, by construction • User Control: the user is in charge and knows exactly what’s happening • Discovery of unexpected relationships • Any combination of values (with AND, OR, NOT criteria) could be supported • Easy to accommodate reviews, popularity, etc (i.e. easy to add more facets) • Simple integration with other retrieval techniques (IR, DB) USNG User Workshop

11. Proposed Approach / Directions Improved Catalogue Searching and Browsing (Exploration) based on the interaction paradigm of Faceted Search. ESA Catalog Faceted Exploration Module General purpose faceted Exploration Services • attribute = facet • attribute value = term of facet • (may hierarchically organized) • metadata may correspond to • explicitly specified features or to • mined features Metadata Data USNG User Workshop

12. Facet Analysis: Preliminary Results • Type of product • Level (e.g. L0, L1, L2) • Quality • Resolution • Format • Content characteristics • Geographical Location • Time (or Time Interval) of acquisition • Orbit range • Provenance • Satellite • Sensor (e.g. SAR) • Acquisition Station • Archiving Centre • Mission (e.g. ERS-1) • Administrative • Status (e.g. Archived, Planned, Acquired, Potential) USNG User Workshop

13. Facet Analysis: Mined Features • The results of mining techniques could be exploited during information exploration services. • For instance according to the internal deliverable about KIM (on Information Mining), the following features could be extracted: • Spectral • Texture • Geometrical Descriptors (the results of segmentation) • more high level features • The result of all such processes could be considered as additional facets USNG User Workshop

14. FORTH’s technology • FORTH is doing research on facet-based indexing, retrieval and browsing. • Several related papers are available at http://www.ics.forth.gr/~tzitzik/publications.htm#CTCA • We are currently developing a general purpose API, called FleXplorer, for enabling faceted exploration. • Subject of continuous improvement • Its current version is being used in a general purpose Web Search Engine (Mitos) USNG User Workshop

15. FleXplorer: Application on Mitos Web Search Engine Zoom-In points USNG User Workshop

16. Experimental Results / Technical Feasibility We are currently conducting experiments for measuring the efficiency of various different architectures and implementations. Scenario A: All metadata loaded in main memory (the FleXplorer approach) • Results: The time to load in memory and compute the zoom-in points of top-L answer is less than a second (for L < 6700) Scenario B: Metadata are stored in a relational DBMS and SQL is used for computing the zoom-in points • Distinction: Flat vs Hierarchically organized attribute values • Results: It takes less than 0.22 sec for hierarchies of depth 5 and answers comprising 200.000 tuples. USNG User Workshop

17. Summarizing and Concluding Remarks • Proposal: • EO Catalogue with Dynamic Taxonomies and Faceted Search • Can accommodate current and future metadata through a generic, yet very user-friendly and efficient interaction scheme • structured metatada • mined features (and their organization) • taxonomies • semantic web data • ... END USNG User Workshop