Apps4 finland shapefiles, wgs84 and other odd terms

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

21/09/2011 2 HistoryFinland first time on the map by Jacob Ziegler (1532)

21/09/2011 3File formats

21/09/2011 4 Combination Roughly 2000 – 3000 coordinate systems Around 300 commonly used GIS file formats

21/09/2011 5 Coordinate systems Polar Coordinate systemCartesian coordinate system Geographic coordinate system

21/09/2011 6 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

21/09/2011 7 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

21/09/2011 8Demo

21/09/2011 9 Map projections: Basic challenge Your paper map and your computer screen is flat World is not!

21/09/2011 10 Map projections Always distortion of  Area  Shape  Direction  Bearing  Distance  Scale

21/09/2011 11Universal Transverse Mercator (UTM)

21/09/2011 12 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

21/09/2011 13Web mercator

21/09/2011 14

21/09/2011 15 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

21/09/2011 16 Geocoding• Transform address / place name to coordinates D2.8.I.5 INSPIRE Data Specification on Addresses – Guidelines

21/09/2011 17Questions?

http://www.apps4finland.fi	1021
http://apps4finland.fi	961
https://testbed25.hexagonit.fi	3
http://demo.primacontrol.fi	1
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Apps4 finland shapefiles, wgs84 and other odd terms

by Apps4Finland on Sep 22, 2011

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Apps4 finland shapefiles, wgs84 and other odd terms — Presentation Transcript