From Geographic Information to GIS - Part II: Processing Data

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

Outline

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

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Introduction

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

I – Processing GPX data

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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

Analysing GPZ File - Metadata
<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>
</trkseg>
</trk>
</gpx>
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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

Analysing GPZ File - Metadata
What does this file tell us?
<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>
</trkseg>
</trk>
</gpx>
GPS Positions: Tracks
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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

GPX Visualisation

GPX Path

Elevation Profil

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

GPX Visualisation

Specific Point
Information

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

GPX Cleaning Manual Process

Potential error

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

GPX Cleaning Manual Process

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

GPX Cleaning Automatic Process

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

GPX Export

e.g., KML, SVG, export

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

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

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

Conversion Process
Example with QGIS → Add Vector Layer

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

Conversion Process
Example with QGIS → Save as ...

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

Conversion Process
From GIS to internet

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

Conversion Process
From GIS to internet

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

Data Storage
A focus on Postgis @ http://postgis.net/

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

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

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

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

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

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

Data Storage
Using GIS and PostGIS

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

III – Processing GPX in VGI

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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

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

OpenStreetMap
More coverage, update, attributes

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OpenStreetMap

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

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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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

Contributing to OpenStreetMap

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

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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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

Field Papers
@ http://fieldpapers.org

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI


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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

Adding data to OpenStreetMap

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI


Missing roads ?

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI


Creation of the missing object

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI


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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

Results

Before
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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

Results

After
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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

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Processing GPX Data

Using GPX in GIS

Using GPX in VGI

Arnaud Vandecasteele
@geotribu

Questions ?

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From Geographic Information to GIS - Part II: Processing Data

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From Geographic Information to GIS - Part II: Processing Data