1/26
Improving volunteered geographic data qualityImproving volunteered geographic data quality
using semantic similarity ...
2/26
Outline
Introduction
Conclusion
Semantic Similarity
P-Rank algorithm
Tobler's Law
OSM Semantic Plugin
Description
Exa...
3/26
Introduction
National Mapping Agencies
What make
National Mapping Agencies
Authoritative ?
Positional Accuracy
Comple...
4/26
Introduction
Geographic Information Quality view as
a Project Management Triangle
5/26
Introduction
Geographic Information Quality view as
a Project Management Triangle
Really?
6/26
Introduction
Could Another Map
be authoritative* ?
* and cheap, and fast, accurate and in the better of worlds free
7/26
Introduction
Volunteered Geographic Information (VGI)
8/26
Introduction
Volunteered Geographic Information (VGI)
the widespread engagement of large numbers of
private citizens,...
9/26
Source: http://wiki.openstreetmap.org/wiki/Stats
OpenStreetMap (OSM) is a collaborative
project to create a free edit...
10/26
Introduction
Data Quality & Volunteered Geographic Information
What about
Data Quality ?
Good geometric accuracy
Hak...
11/26
Introduction
VGI changed the way we
produce, publish and share Geographic Information
BUT
Semantic Quality is still ...
12/26
Semantic Similarity
What is Semantic Similarity ?
Landuse
=
Forest
How to describe a forest in OpenStreetMap
Natural...
13/26
Semantic Similarity
How to measure the semantic similarity ?
● Geometric Model
● Feature Model
● Alignment Model
● N...
14/26
Semantic Similarity
Semantic Network from the OSM Wiki, who it works ?
15/26
Source: OSM WIKI
Semantic Similarity
Semantic Network from the OSM Wiki
16/26
Measuring Semantic similarity
Two entities are similar if :
1 They are referenced by similar entities
2 They referen...
17/26
Semantic similarity
all things are related, but nearbynearby things
are more relatedrelated than distant things
“
”T...
18/26
New Object in a cityNew Object in a cityA
P-Rank score
P-Rankscore
P-Rank
score
P-Rankscore
P-Rank
score
P-Rank
scor...
19/26
Java OpenStreetMap Editor
OpenStreetMap Semantic Plugin
OSM Editor usage stats (source OSM Wiki)
20/26
Description
OpenStreetMap Semantic Plugin
21/26
A B
P-Rank Score
0.18
A C
P-Rank Score
0.35
A D
P-Rank Score
0.05
How similar are they ?
P-Rank scores
OpenStreetMap...
22/26
Creation of a new object
Examples - Creation of a new object
New object
23/26
OpenStreetMap Semantic Plugin
Examples - Edition of an existing object
24/26
OpenStreetMap Semantic Plugin
Examples – Semantic Similarity Evaluation
25/26
Conclusion
The next big question ?
When will VGI be the next authoritative dataset ?
Semantic Similarity can be used...
26/26
Questions ?
Rodolphe Devillers
Marine Geomatics Lab
http://www.marinegis.com/
Memorial University of Newfoundland
Ac...
Upcoming SlideShare
Loading in …5
×

Improving volunteered geographic data quality using semantic similarity measurements

1,157 views
889 views

Published on

Published in: Technology, Education
0 Comments
3 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
1,157
On SlideShare
0
From Embeds
0
Number of Embeds
11
Actions
Shares
0
Downloads
13
Comments
0
Likes
3
Embeds 0
No embeds

No notes for slide

Improving volunteered geographic data quality using semantic similarity measurements

  1. 1. 1/26 Improving volunteered geographic data qualityImproving volunteered geographic data quality using semantic similarity measurementsusing semantic similarity measurements Arnaud Vandecasteele -Arnaud Vandecasteele - Rodolphe DevillersRodolphe Devillers Memorial University of Newfoundland, CanadaMemorial University of Newfoundland, Canada 8th International Symposium on Spatial Data Quality, 30 May - 1 June 2013
  2. 2. 2/26 Outline Introduction Conclusion Semantic Similarity P-Rank algorithm Tobler's Law OSM Semantic Plugin Description Examples
  3. 3. 3/26 Introduction National Mapping Agencies What make National Mapping Agencies Authoritative ? Positional Accuracy Completeness Attribute Accuracy ISO 19113 ISO 19115 ... ISO 19157
  4. 4. 4/26 Introduction Geographic Information Quality view as a Project Management Triangle
  5. 5. 5/26 Introduction Geographic Information Quality view as a Project Management Triangle Really?
  6. 6. 6/26 Introduction Could Another Map be authoritative* ? * and cheap, and fast, accurate and in the better of worlds free
  7. 7. 7/26 Introduction Volunteered Geographic Information (VGI)
  8. 8. 8/26 Introduction Volunteered Geographic Information (VGI) the widespread engagement of large numbers of private citizens, often with little in the way of formal qualifications, in the creation of geographic information “ Goodchild - 2007 ”
  9. 9. 9/26 Source: http://wiki.openstreetmap.org/wiki/Stats OpenStreetMap (OSM) is a collaborative project to create a free editable map of the world + 1 million + 1.8 billion nodes + 180 million ways + 1.9 million relations Started in 2004 Introduction The OpenStreetMap project
  10. 10. 10/26 Introduction Data Quality & Volunteered Geographic Information What about Data Quality ? Good geometric accuracy Haklay – 2010, Girres and Touya – 2010, Ludwig et al., - 2011 But Geographic coverage patchwork Goodchild - 2007 Semantics can be inconsistent Ballatore et al., - 2012, Mooney and Corcoran - 2012
  11. 11. 11/26 Introduction VGI changed the way we produce, publish and share Geographic Information BUT Semantic Quality is still an important issue How to improve semantic quality using a VGI approach ? Research Problem
  12. 12. 12/26 Semantic Similarity What is Semantic Similarity ? Landuse = Forest How to describe a forest in OpenStreetMap Natural = Wood One concept, different representation ! Q ? -> When should we use landuse=forest rather than natural=wood? * https://help.openstreetmap.org/questions/324/when-should-we-use-landuseforest-rather-than-naturalwood 11 different answers and no real general agreement
  13. 13. 13/26 Semantic Similarity How to measure the semantic similarity ? ● Geometric Model ● Feature Model ● Alignment Model ● Network models ● Transformation Model Different models exist: Semantic similarity applied to VGI: Mooney and Corcoran - 2012 Ballatore et al., - 2012 Natural = Wood Landuse = Forest Natural = Wood Landuse = Forest Natural = Wood Landuse = Forest Measure? Semantic Network created from the OpenStreetMap Wiki Point Pattern analysis and semantic pattern
  14. 14. 14/26 Semantic Similarity Semantic Network from the OSM Wiki, who it works ?
  15. 15. 15/26 Source: OSM WIKI Semantic Similarity Semantic Network from the OSM Wiki
  16. 16. 16/26 Measuring Semantic similarity Two entities are similar if : 1 They are referenced by similar entities 2 They reference similar entities A B C = A B C = Semantic Similarity P-Rank Algorithm
  17. 17. 17/26 Semantic similarity all things are related, but nearbynearby things are more relatedrelated than distant things “ ”Tobler - 1970 Semantic similarity and Geography Tobler's first law of geography
  18. 18. 18/26 New Object in a cityNew Object in a cityA P-Rank score P-Rankscore P-Rank score P-Rankscore P-Rank score P-Rank score Semantic similarity Applied Tobler's first law to semantic similarity
  19. 19. 19/26 Java OpenStreetMap Editor OpenStreetMap Semantic Plugin OSM Editor usage stats (source OSM Wiki)
  20. 20. 20/26 Description OpenStreetMap Semantic Plugin
  21. 21. 21/26 A B P-Rank Score 0.18 A C P-Rank Score 0.35 A D P-Rank Score 0.05 How similar are they ? P-Rank scores OpenStreetMap Semantic Plugin (aka OSMantic) Description A AC
  22. 22. 22/26 Creation of a new object Examples - Creation of a new object New object
  23. 23. 23/26 OpenStreetMap Semantic Plugin Examples - Edition of an existing object
  24. 24. 24/26 OpenStreetMap Semantic Plugin Examples – Semantic Similarity Evaluation
  25. 25. 25/26 Conclusion The next big question ? When will VGI be the next authoritative dataset ? Semantic Similarity can be used to enhance the quality of VGI dataset OSM Semantic plugin uses a collaborative approach to reduce the potential semantic similarity How to improve the results: ● Using the Tag Info database to know the most used tags ● By mixing the Geographic and the semantic approach (Ballatore + Mooney)
  26. 26. 26/26 Questions ? Rodolphe Devillers Marine Geomatics Lab http://www.marinegis.com/ Memorial University of Newfoundland Acknowledgements Natural Science and Engineering Research Council of Canada (NSERC) Andrea Ballatore for sharing his results

×