Kevin Baker, Pascal Brackman, Philippe De Maeyer, Rik Van de Walle University Ghent, Belgium; RouteYou, Belgium Topic: “Reconstructing movement traces through a hybrid map-matching algorithm”

1. AGILE 2013 – Leuven, May 14-17, 2013
Reconstructing movement traces
through a hybrid map-matching
algorithm
Understanding Urban Cycling: A Data
Challenge
Kevin Baker

2. AGILE 2013 – Leuven, May 14-17, 2013
Research Framework
• Branding slogan: “Plan your nicest route”
– Specific information about the road infrastructure
and surroundings focused on his application

3. AGILE 2013 – Leuven, May 14-17, 2013
Research Framework
• PhD research:
– “Mapping Linear Landscapes - Geosemantic
methods for information extraction, validation
and enrichment using dynamic geodata”
– intelligent aggregation and combination of novel
geographic information from a dynamic
community

4. AGILE 2013 – Leuven, May 14-17, 2013
Algorithm

5. AGILE 2013 – Leuven, May 14-17, 2013
Algorithm

6. AGILE 2013 – Leuven, May 14-17, 2013
Algorithm

7. AGILE 2013 – Leuven, May 14-17, 2013
Algorithm
• Software: FME / Python/OSRM Routing Engine

8. AGILE 2013 – Leuven, May 14-17, 2013
Workflow
• Hybrid map-matching algorithm
• Geographical: Point Search Algorithm
• Semantic: Attribute matching
• Topological: Shortest Path Routing Engine

9. AGILE 2013 – Leuven, May 14-17, 2013
Workflow
• Vector Database:
– TomTom
• Preprocessing steps twofold:
Routable dataset Point cloud

10. AGILE 2013 – Leuven, May 14-17, 2013
Workflow
• Raw dataset
– Create plausible trips per PERSONID
• Time between registrations < 5 minutes
• Remove outliers/error:
– HDOP < 5
– Distance between
registrations (<2500 m)
– outliers/error in Lat/Lon

11. AGILE 2013 – Leuven, May 14-17, 2013
Workflow
• Raw dataset
– Analyse and filter trips on time passed and
meanspeed

12. AGILE 2013 – Leuven, May 14-17, 2013
Workflow
• Raw dataset
– Resulting trips (3302)
• PersonID
• TripID
• Starttime
• Endtime
• Meanspeed

13. AGILE 2013 – Leuven, May 14-17, 2013
Workflow
• Point Search Algorithm
– Detect unambigious points along a trace:
• Dual carriage way
• Parallel roads
• Bearing difference
• Analyse closest
candidates

14. AGILE 2013 – Leuven, May 14-17, 2013
Workflow
• Point Search Algorithm
– Variable parameters in function of quality:
• Dynamic search distance (B)
• Search interval (ΔA)
• Allowed bearing difference
• Number of closest candidates to analyse

15. AGILE 2013 – Leuven, May 14-17, 2013
Workflow
• Similarity measure
– A is routed segment
– B is original segment of trace
A
B

16. AGILE 2013 – Leuven, May 14-17, 2013
Workflow
• Similarity measures (Quality dependend threshold)
– Frèchet distance
– Relative/Absolute length difference
– Area between segments
– Turning function

17. AGILE 2013 – Leuven, May 14-17, 2013
Workflow
• Hybrid map-matching algorithm

18. AGILE 2013 – Leuven, May 14-17, 2013
Result: overview
Good similarity
Bad similarity

19. AGILE 2013 – Leuven, May 14-17, 2013
Result: overview
Good similarity Bad similarity

20. AGILE 2013 – Leuven, May 14-17, 2013
Result: comparison
• Individual trips
Created Trip
TRIPID: 3034
Meanspeed: 4.88
Person : 207
Traveltime: 0:36:36
Additional trail
TRIPID: 207-961
Person : 207
Traveltime: 0:16:00

21. AGILE 2013 – Leuven, May 14-17, 2013
Result: comparison
• Individual trips
Created Trip
TRIPID: 1328
Meanspeed: 6.9955
Person : 146
Traveltime: 0:49:25
Additional trail
TRIPID: 146-964
Person : 146
Traveltime: 0:15:00

22. AGILE 2013 – Leuven, May 14-17, 2013
Result: comparison
• Heatmap of ‘additional cycle trips’ (Raster)
Max
Min
Remark: Pixelsize of 4m

23. AGILE 2013 – Leuven, May 14-17, 2013
Result: comparison
• Vector dataset with continuous color on count
Max
Min

24. AGILE 2013 – Leuven, May 14-17, 2013
Result: comparison

25. AGILE 2013 – Leuven, May 14-17, 2013
Discussion and Research Outlook
• Customize routable data to specific activity
– Exclude specific highwayclasses?
– Resistance on edges (fix vs variable)?
• Extensive post processing of delta (red lines)
– How far can the automatic integration go?
– Crowdsourcing/Outsourcing?
• Fine-tuning the Point Search Algorithm
• Extend similarity measure and thresholds
• Resulting trip parameters

26. AGILE 2013 – Leuven, May 14-17, 2013
Q&A