From Event to Action: Accelerate Your Decision Making with Real-Time Automation
From Geographic Information to GIS
1. From Geographic Information to GIS
Getting the Map into the computer
Part I: Data Collection
Arnaud
Vandecasteele
Memorial Univ. of
Newfoundland,
Canada
3/02/2013
2. Outline
Introduction
1 - Data Collection
2 – Conversion process
3 – Data Storage
4 – Data Analysis
Conclusion
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Introduction
3. Objectives
Methods to acquire GIS data, particularly via the GPS
Methods to create new GIS data
Processes to edit existing GIS data
Types and sources of error potentially associated with GIS data
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Introduction
5. From physical reality to computer
How to represent reality ?
Fonseca et al., 2002
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Introduction
6. From physical reality to computer
REAL WORLD
Source: http://www.uvm.edu/~gis/
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GRID RASTER VECTOR 6/36
Introduction
7. Data Collection Process
Data Conversion Data Data
Collection Process Storage Analysis
.Gpx
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Data Collection Conversion Process Data Storage Data Analysis
8. Geodata collecting
Two main types of data capture:
●
Primary data sources (direct measurement)
collected in digital format specifically
for use in GIS (e.g., GPX, Satellites Images)
●
Secondary sources (indirect derivation)
need to be converted into a suitable
digital for use in a GIS project (e.g., CSV, Excel, etc.)
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Data Collection Conversion Process Data Storage Data Analysis
9. ●
Primary data sources (direct measurement)
collected in digital format specifically
for use in GIS (e.g., GPX, Satellites Image)
Raster Data Capture Vector Data Capture
(Remote Sensing)
You are not directly measuring GPS, LiDAR
the object, but is reflectance
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Data Collection Conversion Process Data Storage Data Analysis
10. Geodata collecting - GPS
●
Primary data sources (direct measurement)
collected in digital format specifically
for use in GIS (e.g., GPS, Satellites Image)
Example of a GPX file
<?xml version="1.0" encoding="UTF-8"?>
<gpx version="1.0">
<name>Example gpx</name>
<wpt lat="46.57638889" lon="8.89263889">
<ele>2372</ele>
Example of <name>Example Points</name>
A waypoint </wpt>
<trk><name>Example gpx</name><number>1</number><trkseg>
<trkpt lat="46.57608" lon="8.89241"><ele>2376</ele><time>2007-10-14T10:09:57Z</time></trkpt>
<trkpt lat="46.57619" lon="8.89252"><ele>2375</ele><time>2007-10-14T10:10:52Z</time></trkpt>
Example of <trkpt lat="46.57641" lon="8.89266"><ele>2372</ele><time>2007-10-14T10:12:39Z</time></trkpt>
a track </trkseg></trk>
</gpx>
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Data Collection Conversion Process Data Storage Data Analysis
11. What is GPS
The Global Positioning System (GPS) is a constellation
of satellites that is used to calculate your position.
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Data Collection Conversion Process Data Storage Data Analysis
12. How GPS works ?
1
20130203-1045-3001
1 Each satellite continuously
broadcasts timing information
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Data Collection Conversion Process Data Storage Data Analysis
13. How GPS works ?
1
20130203-1045-3001
1 Each satellite continuously
broadcasts timing information
2
20130203-1045-3148
2 A GPS receiver measures
distance using the travel time
of radio signals
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Data Collection Conversion Process Data Storage Data Analysis
14. How GPS works ?
1 Each satellite continuously
broadcasts timing information
3
2 A GPS receiver measures
distance using the travel time
of radio signals
3 We are somewhere on the circle
where these two spheres intersect
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Data Collection Conversion Process Data Storage Data Analysis
15. How GPS works ?
Trilateration (Triangulation)
1 Each satellite continuously
broadcasts timing information
2 A GPS receiver measures
distance using the travel time
4
of radio signals
3 We are somewhere on the circle
where these two spheres intersect
4 The receiver calculates the distance
to each satellite and trilaterates
its own position 15/36
Data Collection Conversion Process Data Storage Data Analysis
16. Are GPS perfect ?
Accuracy – sources of errors
●
Ionospheric effects ± 5 meters
●
Tropospheric effects ± 0.5 meter
●
Ephemeris errors ± 2.5 meters
●
Satellite clock errors ± 2 meters
●
Multipath distortion ± 1 meter
●
Numerical errors ± 1 meter
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Data Collection Conversion Process Data Storage Data Analysis
17. Geodata conversion
Data Conversion Data Data
Collection Process Storage Analysis
.Gpx
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Data Collection Conversion Process Data Storage Data Analysis
18. Geodata conversion process
<?xml version="1.0" encoding="UTF-8"?>
<gpx version="1.0">
<name>Example gpx</name> .Gpx
<wpt lat="46.57638889" lon="8.89263889">
<ele>2372</ele>
<name>Example Points</name>
</wpt>
<trk><name>Example gpx</name><number>1</number><trkseg>
<trkpt lat="46.57608" lon="8.89241"><ele>2376</ele><time>2007-10-14T10:09:57Z</time></trkpt>
<trkpt lat="46.57619" lon="8.89252"><ele>2375</ele><time>2007-10-14T10:10:52Z</time></trkpt>
<trkpt lat="46.57641" lon="8.89266"><ele>2372</ele><time>2007-10-14T10:12:39Z</time></trkpt>
</trkseg></trk>
</gpx>
Point Line (track) .Gis
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Data Collection Conversion Process Data Storage Data Analysis
19. Geodata conversion process
GPSBabel @ http://www.gpsbabel.org
Converts data between popular GPS
Extensive data manipulation abilities
Multi-platform (e.g., Windows, Mac, Linux)
User Interface
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Data Collection Conversion Process Data Storage Data Analysis
20. Geodata Storage
Data Conversion Data Data
Collection Process Storage Analysis
.Gpx
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Data Collection Conversion Process Data Storage Data Analysis
21. Geodata storing
Proprietary Systems
Oracle Spatial, Microsoft SQL Server
Open Source
PostgreSQL/Gis, MySQL, SQLite
Service Based
Google BigTable, Amazon SimpleDB
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Data Collection Conversion Process Data Storage Data Analysis
22. Geodata storing
PostGis @ http://postgis.refractions.net/
Project started in 2001
Based on Postgresql
Many GeoFunctions (e.g., Buffer, Intersects)
Geometric, Geographic and Raster data
MySql Spatial @ http://dev.mysql.com/
Integrated into MySQL since 4.1
Geometric data (plan)
No projection
Few spatial function
SpatialLite @ http://www.gaia-gis.it/spatialite/
Based on SQL Lite
Minimal weight (250 ko)
Many GeoFunctions (e.g., Buffer, Intersects)
User Interface
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Data Collection Conversion Process Data Storage Data Analysis
23. How GeoData are storing ?
GPX <trk><name>Example gpx</name><number>1</number><trkseg>
<trkpt lat="46.57608" lon="8.89241"><ele>2376</ele><time>2007-10-14T10:09:57Z</time></trkpt>
<trkpt lat="46.57619" lon="8.89252"><ele>2375</ele><time>2007-10-14T10:10:52Z</time></trkpt>
<trkpt lat="46.57641" lon="8.89266"><ele>2372</ele><time>2007-10-14T10:12:39Z</time></trkpt>
</trkseg></trk>
WKT WKB
Well Know Text Well Know Binary
ele time geom_wkt ele time geom_wkb
1 2007-10- LINESTRING(46.5760 1 2007-10- 010200002031BF0D0
14T10:09:57Z 8 8.89241,46.57619 14T10:09:57Z 00900000085EB5140
8.89252,46.57641 E...1F6285CDFAED56
8.89266) 7C185EB5118DF664
E41
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Data Collection Conversion Process Data Storage Data Analysis
24. Data Conversion Data Data
Collection Process Storage Analysis
.Gpx
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Data Collection Conversion Process Data Storage Data Analysis
25. Geodata visualisation - desktop
QGIS
@ http://www.qgis.org/
ArcGis
@ http://www.esri.com
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Data Collection Conversion Process Data Storage Data Analysis
26. Geodata visualisation - internet
OpenLayers
@ http://www.openlayers.org/
ArcGis
@ http://www.arcgis.com
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Data Collection Conversion Process Data Storage Data Analysis
27. Quality insurance
Positional accuracy
Defined as the closeness of locational information to the true position
Attribute accuracy
Defined as the closeness of attribute values to their true value
Logical consistency
Refers to the internal consistency of the data structure,
particularly applies to topological consistency
Completeness
Concerns the degree to which the data exhausts the universe of possible items
Lineage
A record of the data sources and of the operations which created the database 27/36
Conclusion
28. OSGEO-Live
Looking for software?
OSGEO-Live
http://live.osgeo.org/
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Conclusion
29. To go further
Geographic Information Systems and Science
Paul A. Longley, Mike Goodchild,
David J. Maguire, David W. Rhind
2010
A primer of GIS
Fundamental Geographic and cartographic concepts
Francis Harvey
2008 29/36
Conclusion
30. Have Fun with Geography
Let's GeoPlay
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Conclusion
31. Geocaching
Can I Geo Play ?
Geocaching (http://www.geocaching.com/)
Outdoor recreational activity in which the participants
use a GPS to hide and seek containers,
called "geocaches" or "caches", anywhere in the world
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Conclusion
33. OpenStreetMap
Can I Geo Play ?
OpenStreetMap (http://www.openstreetmap.org/)
Outdoor recreational activity in which the participants
create free geographic data for the world.
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35. Have Fun with Geography
Activity 1 -
Find the Geocache located at :
Nad 83 → Lat 47°34.334, Lon -52°43.858
Activity 2 -
Record OpenStreetMap GeoData
Thanks to the weather
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