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Maps
This document provides an overview of maps and map projections for web developers. It discusses common map projections like Mercator and UTM, how to represent latitude and longitude, tools for working with maps like Proj4 and GDAL, popular map providers like Google Maps, Bing Maps and OpenStreetMap, and how to create your own map server using tools like Mapnik, PostGIS, and tile rendering.
Maps
- 1. Maps For web developersand enthusiasts
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- 3. Contents 1. Map projections 2.Map providers 3. How to create your own map
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- 6. …when using projections. •Projections • Datums • Geocentric datums • WSG84 • Local datums • NAD83 • NAD27 • ED1950
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- 8. Latitude and Longitude •Latitude, Longitude = 42° 41' 53.0916" , 23° 19' 18.894“ (geographic coordinates) • Latitude = 42 + 41/60 + 53.0916/3600 = 42.698081 (decimal) • Longitude = 23 + 19/60 + 18.894/3600 = 23.317191 (decimal) • Latitude, Longitude = 42.698081, 23.317191 (in decimal) • 1 min ≈ 1.85km • 1 sec ≈ 31m • Latitude distance ≈ 42.67 * 60 * 1.85 ≈ 4 736km • Longitude distance ≈ 23.32 * 60 * 1.85 ≈ 2 588km
- 9. • Use atleast 6 symbols after the dot for keeping max precision • Degrees vary in different places in the world by 21.5km
- 10. Universal Traverse Mercator UTM– 328204 E (easting), 4746040 N (northing)
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- 13. Equidistant cylindrical map •Showing distances (km) between lines connected by identical lines. Each graphic scale is only valid along its own parallel, or the one symmetrically opposite the Equator. Only the vertical scale is valid anywhere, and none of the four is valid if rotated.
- 14. Equatorial van derGrinten III map • Parallels are straight but not standard lines.
- 15. Equatorial cylindrical equidistantmap • Equatorial cylindrical equidistant map showing standard lines. Markers divide segments proportionally.
- 16. Transverse cylindrical equidistantmap • Transverse cylindrical equidistant map showing standard lines, which no more coincide with meridians and the Equator except accidentally. Markers divide segments proportionally.
- 17. Equatorial sinusoidal map •Equatorial sinusoidal (Sanson-Flamsteed) map showing standard lines. Markers divide segments proportionally.
- 18. Normal Werner map •Normal Werner map showing standard lines. Markers divide segments proportionally.
- 19. Polar azimuthal equidistantmap • Polar azimuthal equidistant map showing standard lines. Markers divide segments proportionally.
- 20. Which projection isbest • • • • • Depends on the purpose What we want to show on the map Know target audience Put important information on map More in “How to lie with maps” http://imgs.xkcd.com/comics/map_projections.png
- 21. Tools • Proj4 –conversions between cartographic projections • http://trac.osgeo.org/proj/ • GEOS – geometry processing and analysis • http://trac.osgeo.org/geos/ • GDAL – geometry data abstraction, translation and processing • http://www.gdal.org/
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- 24. Google Maps • https://www.google.com/maps/preview •Free for commercial use with public access with 25 000 requests per day • Zoom level up to 18-23 depend on area • Started 2004 as C++ application by Lars and Jens Rasmussen from Sydney’s Where 2 Technologies • 2005 first announced • Satellite images updated regularly, not older than 3y • 54% usage of mobile apps
- 25. Bing Maps • • • • • http://www.bing.com/maps/ API with90 days trial December 2005 first release 2009 rebranded from Live Search Maps to Bing Maps Based on MS MapPoint (.NET application to view, edit and integrate maps) and TerraServer (free repository of aerial imagery and topographic maps provided by USGS, known as MS Research Maps as of 2010)
- 26. MapQuest • http://www.mapquest.com/ • API,free with app key • Free map tiles • Static map • • • • Founded 1967 as Cartographic Services 1994 Renamed to GeoSystems Global Corporation 1996 launched as a web service 2000 Acquired by AOL
- 27. ArcGIS Online (ESRI) •http://www.arcgis.com/home/webmap/viewer.html • ESRI • Founded 1969, California USA • API, paid • ArcGIS desktop application • • • • Load data from database Creating and using maps as shape file Compiling geographic data Analyzing mapped information • ArcGIS reader • 40% market share in GIS software • Paid license • Proprietary data formats
- 28. HERE maps • http://here.com/ •API • Map tiles • Static maps • • • • • • • • 2001 as SmartGo 2006 acquired gate 5 – Berlin-based route planning software 2007 acquired NAVTEQ 2008 acquired Plazes, Plum, Dopplr - geo related web sites 2010 acquired Metacarta 2011 bought earthmine 2011 Former Ovi Maps (2007-2010) renamed to Nokia Maps (2011-2012) 2012 rebranded to HERE Maps
- 29. CloudMade • • • • http://maps.cloudmade.com/ Co-founded by SteveCoast in 2007 Many OSM based GIS APIs and services Map style editor
- 30. OpenStreetMap • • • • • • http://www.openstreetmap.org/ Collaborative project starterby Steve Coast in UK in 2004 2006 OpenStreetMap Foundation created to support the project 2006 OSM reuses Yahoo aerial photography AND donated road data The State of the Map conference • first held 2007 • 9 000 registered users • Sponsored by Google, Yahoo and Multimap • 1 million users (not all contributing) • Open Database License • Uses Ruby On Rails for back end Registered users
- 31. Creating own mapserver
- 32. What we need •Tiles - images of 256 x 256 pixels each • Already pre-rendered or rendered on demand from map database • Use from 3rd party provider (at charge or free) • JavaScript API library • OpenLayers – powerful and long-established • Leaflet – lightweight and easy-to-learn
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- 37. Mapstraction • • • • • • • • • • http://mapstraction.com/ CloudMade ESRI ArcGIS Google MapQuest andMapQuest Open Microsoft Bing Nokia HERE OpenLayers Ordnance Survey OpenSpace Yandex
- 38. What is inthe black box • • • • • Planet file (33Gb of data so far) or extract (Geofabrik, Metro Extracts, CloudMade) PostgreSQL + PostGIS Apache + mod_tile for serving tiles Mapnik slippy_map
- 39. Put data indatabase • • • • • Get planet file or extract Use osm2pgsql to import the data into Postgres Add world boundaries, coastlines etc. Modify stylesheets (not required) render_list to pre-render tiles
- 41. Example maps • http://en.wikipedia.org/wiki/List_of_online_map_services •http://alpha.map1.eu/ • http://bihor-county.map2web.eu/
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