From Geographic Information to GIS

From Geographic Information to GISGetting the Map into the computer

Part I: Data Collection

Arnaud Vandecasteele

Memorial Univ. of Newfoundland,

Canada

3/02/2013

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Outline

Introduction

1 - Data Collection

2 – Conversion process

3 – Data Storage

4 – Data Analysis

Conclusion

Introduction

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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

Introduction

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GeoSpatial Revolution

Introduction

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Fonseca et al., 2002

From physical reality to computer

How to represent reality ?

Introduction

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From physical reality to computer

REAL WORLD

VECTORGRID RASTER

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Source: http://www.uvm.edu/~gis/

Introduction

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Data Collection Process

.Gpx

ConversionProcess

DataCollection

DataStorage

DataAnalysis

Data Collection Conversion Process Data Storage Data Analysis

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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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Raster Data Capture(Remote Sensing)

You are not directly measuringthe object, but is reflectance

Vector Data Capture

GPS, LiDAR


for use in GIS (e.g., GPX, Satellites Image)


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<?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><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>

Example of a GPX file

Example of a track

Example ofA waypoint


for use in GIS (e.g., GPS, Satellites Image)

Geodata collecting - GPS


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What is GPS

The Global Positioning System (GPS) is a constellation of satellites that is used to calculate your position.


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How GPS works ?

Each satellite continuously broadcasts timing information

20130203-1045-3001

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A GPS receiver measures distance using the travel time of radio signals

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How GPS works ?

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How GPS works ?


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We are somewhere on the circle where these two spheres intersect

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Trilateration (Triangulation)

How GPS works ?


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The receiver calculates the distance to each satellite and trilaterates its own position

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We are somewhere on the circle where these two spheres intersect

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Are GPS perfect ?

● 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

Accuracy – sources of errors


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Geodata conversion

.Gpx

ConversionProcess

DataCollection

DataStorage

DataAnalysis


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<?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><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>

.Gpx

Geodata conversion process

Point Line (track)


.Gis

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Geodata conversion process

GPSBabel @ http:/ /www.gpsbabel.org

Converts data between popular GPS Extensive data manipulation abilitiesMulti-platform (e.g., Windows, Mac, Linux)User Interface


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Geodata Storage

.Gpx

ConversionProcess

DataCollection

DataStorage

DataAnalysis


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Proprietary SystemsOracle Spatial, Microsoft SQL Server

Open SourcePostgreSQL/Gis, MySQL, SQLite

Service BasedGoogle BigTable, Amazon SimpleDB

Geodata storing


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Geodata storing

PostGis @ http:/ /postgis.refract ions.net/

Project started in 2001Based on PostgresqlMany GeoFunctions (e.g., Buffer, Intersects)Geometric, Geographic and Raster data

MySql Spatial @ http:/ /dev.mysql.com/

Integrated into MySQL since 4.1Geometric data (plan)

No projectionFew spatial function

SpatialLite @ http://www.gaia-gis. it /spat ial i te/

Based on SQL LiteMinimal weight (250 ko)Many GeoFunctions (e.g., Buffer, Intersects)User Interface


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How GeoData are storing ?

<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

ele time geom_wkt1 2007-10-

14T10:09:57ZLINESTRING(46.57608 8.89241,46.57619 8.89252,46.57641 8.89266)

ele time geom_wkb1 2007-10-

14T10:09:57Z010200002031BF0D000900000085EB5140E...1F6285CDFAED567C185EB5118DF664E41

WKTWell Know Text

WKBWell Know Binary


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.Gpx

ConversionProcess

DataCollection

DataStorage

DataAnalysis


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Geodata visualisation - desktop


ArcGis@ http://www.esri.com

QGIS@ http://www.qgis.org/

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Geodata visualisation - internet


ArcGis@ http://www.arcgis.com

OpenLayers@ http://www.openlayers.org/

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Quality insurance

Positional accuracyDefined as the closeness of locational information to the true position

Attribute accuracyDefined as the closeness of attribute values to their true value

Logical consistencyRefers to the internal consistency of the data structure,

particularly applies to topological consistency

CompletenessConcerns the degree to which the data exhausts the universe of possible items

LineageA record of the data sources and of the operations which created the database

Conclusion

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Looking for software?OSGEO-Live

http://live.osgeo.org/

OSGEO-Live

Conclusion

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Geographic Information Systems and SciencePaul A. Longley, Mike Goodchild, David J. Maguire, David W. Rhind2010

To go further

Conclusion

A primer of GISFundamental Geographic and cartographic concepts

Francis Harvey 2008

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Let's GeoPlay

Conclusion

Have Fun with Geography

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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

Conclusion

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Conclusion

Geocaching

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Can I Geo Play ?

OpenStreetMap (http://www.openstreetmap.org/)

Outdoor recreational activity in which the participants create free geographic data for the world.

OpenStreetMap

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OpenStreetMap

OpenStreetMap @ http://www.openstreetmap.org/

Conclusion

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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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Equipment

GPS Mobile App Walking Paper

From Geographic Information to GIS

Technology

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