1. From Geographic Information to GIS
Getting the Map into the computer
Part II: Processing Data
Arnaud
Vandecasteele
Memorial Univ. of
Newfoundland,
Canada
3/02/2013

2. Outline
Introduction
1 – Processing GPX Data
2 – Using GPX Data in GIS
3 – Using GPX Data in VGI
Conclusion
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Introduction

3. Objectives
Methods and tools to process your GPX data
Integration of your GPX inside a GIS platform
Integration of your GPX inside a VGI platform
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Introduction

4. I – Processing GPX data
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5. Data Collection Process
GPX, or GPS eXchange is a light-weight XML data format
for the interchange of GPS data (waypoints, route and tracks)
GPX File
<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<gpx ...>
Metadata
.Gpx
<metadata> ... </metadata>
Data
Track
Waypoint
<trk>
<trkseg>
<trkpt lat="#" lon="#">
<ele>#</ele>
</trkpt>
<trkpt ...>
….
</trkpt>
</trkseg>
</trk>
<wpt lat="#" lon="#">
<ele>#</ele>
<name>...</name>
…
</wpt>
<wpt lat="#" lon="#">
…
</wpt>
</gpx>
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

6. Data Collection Process
Analysing GPZ File - Metadata
<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<gpx
...
creator="eTrex 20" version="1.1"
...
<metadata>
<link href="http://www.garmin.com">
<text>Garmin International</text>
</link>
<time>2013-02-05T12:03:16Z</time>
</metadata>
<trk>
<name>MMMMMMMK3 08:33:02</name>
<trkseg>
<trkpt lat="47.5536662433" lon="-52.7926951088"><ele>169.81</ele><time>2013-02-05T11:44:41Z</time></trkpt>
<trkpt lat="47.5540290959" lon="-52.7929564565"><ele>168.37</ele><time>2013-02-05T11:44:50Z</time></trkpt>
<trkpt lat="47.5542206224" lon="-52.7935003582"><ele>167.41</ele><time>2013-02-05T11:44:57Z</time></trkpt>
<trkpt lat="47.5541830715" lon="-52.7945925202"><ele>167.41</ele><time>2013-02-05T11:45:07Z</time></trkpt>
<trkpt lat="47.5543716643" lon="-52.7948338352"><ele>166.93</ele><time>2013-02-05T11:45:15Z</time></trkpt>
</trkseg>
</trk>
</gpx>
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

7. Data Collection Process
Analysing GPZ File - Metadata
What does this file tell us?
<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<gpx
...
creator="eTrex 20" version="1.1"
...
GPS Metadata
<metadata>
<link href="http://www.garmin.com">
<text>Garmin International</text>
</link>
<time>2013-02-05T12:03:16Z</time>
</metadata>
<trk>
<name>MMMMMMMK3 08:33:02</name>
<trkseg>
<trkpt lat="47.5536662433" lon="-52.7926951088"><ele>169.81</ele><time>2013-02-05T11:44:41Z</time></trkpt>
<trkpt lat="47.5540290959" lon="-52.7929564565"><ele>168.37</ele><time>2013-02-05T11:44:50Z</time></trkpt>
<trkpt lat="47.5542206224" lon="-52.7935003582"><ele>167.41</ele><time>2013-02-05T11:44:57Z</time></trkpt>
<trkpt lat="47.5541830715" lon="-52.7945925202"><ele>167.41</ele><time>2013-02-05T11:45:07Z</time></trkpt>
<trkpt lat="47.5543716643" lon="-52.7948338352"><ele>166.93</ele><time>2013-02-05T11:45:15Z</time></trkpt>
</trkseg>
</trk>
</gpx>
GPS Positions: Tracks
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

8. Data Collection Process
GPX Visualisation
GPX Path
Elevation Profil
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

9. Data Collection Process
GPX Visualisation
Specific Point
Information
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

10. Data Collection Process
GPX Cleaning Manual Process
Potential error
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

11. Data Collection Process
GPX Cleaning Manual Process
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

12. Data Collection Process
GPX Cleaning Automatic Process
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

13. Data Collection Process
GPX Export
e.g., KML, SVG, export
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

14. Data Collection Process
GPX Comparison, two GPS same place/time
Second GPX
First GPX
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

15. Data Collection Process
How to get accurate GPS positions?
Geometric Dilution of Precision (GDOP) :
●
Horizontal DOP (HDOP)
●
Vertical DOP (VDOP)
●
Positional DOP (PDOP)
●
Time DOP (TDOP)
Good GDOP
Bad GDOP
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

16. II - Using GPX in GIS
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17. Conversion Process
Example with QGIS → Add Vector Layer
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

18. Conversion Process
Example with QGIS → Save as ...
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

19. Conversion Process
From GIS to internet
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

20. Conversion Process
From GIS to internet
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

21. Data Storage
A focus on Postgis @ http://postgis.net/
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

22. Data Storage
What is PostGIS ?
Postgis is a spatial extension for Postgresql:
●
Provides Spatial Data Type
●
Provides Spatial Indexing
●
Provides Spatial Functions
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

23. Data Storage
PostGIS DataTypes
Point
Line
LinearRing
Multypolygon
+ MultiLine, MultiPolygon, GeometryCollection...
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

24. Data Storage
PostGIS Spatial Indexing
R-tree
Quadtree
Grid-based
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

25. Data Storage
Example:
ST_Simplify(geom, tolerance)
PostGIS Spatial Functions
Construction
Serialisation
Predicates
Analysis
Accessors
Builders
Aggregates
1
2
3
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

26. Data Storage
Using GIS and PostGIS
1 Import your data into PostGIS
2 Load your data into QGIS
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

27. Data Storage
Using GIS and PostGIS
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

28. III – Processing GPX in VGI
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29. OpenStreetMap
What is OpenStreetMap?
Geographic data
●
For driving, riding, walking,
boating, skiing, hiking, anything
●
Free (ODBL License)
●
Wiki-like editing
+
=
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

30. Volunteered Geographic Information
What not just use commercial map providers?
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

31. OpenStreetMap
More coverage, update, attributes
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32. OpenStreetMap
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

33. OpenStreetMap
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34. OpenStreetMap
Paris : Aout 2006
Paris : Décembre 2010
Source : http://www.geofabrik.de
Processing GPX Data
Using GPX in GIS
Using GPX in VGI
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35. OpenStreetMap
Humanitarian OSM
Source :http://www.flickr.com/photos/itoworld/
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

36. Contributing to OpenStreetMap
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

37. OpenStreetMap Objects
Nodes
lines
Polygon
Relations
Relations
Geometric Objects
Processing GPX Data
Using GPX in GIS
Conceptual
Objects
Using GPX in VGI
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38. OpenStreetMap Objects
higway = secondary
higway = Residential
leisure = garden
ay = Tertiary
building = yes
tourism = museum
higway = trunk
tunnel = yes
higway = trunk
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

39. Contributing to OpenStreetMap
Field Papers
@ http://fieldpapers.org
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

40. Contributing to OpenStreetMap
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

41. Adding data to OpenStreetMap
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

42. Adding data to OpenStreetMap
Missing roads ?
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

43. Adding data to OpenStreetMap
Creation of the missing object
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

44. Adding data to OpenStreetMap
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

45. Results
Before
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

46. Results
After
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Processing GPX Data
Using GPX in GIS
Using GPX in VGI

47. 47/48
Processing GPX Data
Using GPX in GIS
Using GPX in VGI

48. Arnaud Vandecasteele
@geotribu
Questions ?
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