1. Shapefiles, WGS84 and other odd terms
Workshop on Open Location Data
Pekka Sarkola

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History
Finland first time on the map by Jacob Ziegler (1532)

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File formats

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Combination
 Roughly 2000 – 3000 coordinate systems
 Around 300 commonly used GIS file formats

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Coordinate systems
Polar Coordinate system
Cartesian coordinate system Geographic coordinate system

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Coordinate systems – no problems...
 What is origin?
 What is direction?
 What is unit of measurement?
 You have choices:
 Thousands of different coordinate systems
 Good ones and bad ones
 Old vs new
 Local vs global

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Geographic Coordinate Systems
 Latitude (leveys), longitude (pituus) and ellipsoid height
 Common datums / geodetic systems
 WGS 84, 72, 64, and 60
 ETRS89
 NAD83 / NAD27 : USA
 OSGB36: GB
 ED50: European Datum
 Hayford International 1924: base of

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Demo

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Map projections: Basic challenge
 Your paper map and your computer screen is flat
 World is not!

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Map projections
 Always distortion of
 Area
 Shape
 Direction
 Bearing
 Distance
 Scale

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Universal Transverse Mercator (UTM)

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Finnish Coordinate Systems
 Kartastokoordinaattijärjestelmä (KKJ)
 Old one, from 1970’s
 Map projection:
 Transverse mercator, 6 zones
 EUREF-FIN
 New, based on ETRS89
 Several map projections
 ETRS-TM35FIN
 ETRS-TM21, 27, 33
 ETRS-GK19-31

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Web mercator

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Georeferencing, geotagging,
 Georeferencing
 ”To georeference something means to define its existence in
physical space”, Wikipedia
 Especially for aerial and satellite imagery
 Geotagging
 Add coordinates to single item, like picture taken with mobile
phone

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Geocoding
• Transform address / place name to coordinates
D2.8.I.5 INSPIRE Data Specification on Addresses – Guidelines

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Questions?