structure: overview geocoding coordinate system overlays conclusion questions november 07...
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Structure: Overview Geocoding Coordinate System Overlays Conclusion Questions November 07 Computational Aspects of GIS Oliver Walzer Analyzing Google Maps Overview Announced February 8 th, 2005 Beta until October 6 th, 2005 Second API version released April 3 rd, 2006 Geocoding service added June 11 th, 2006 User friendly Fast Public available APITRANSCRIPT
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
Analyzing Google Maps
Oliver WalzerComputational Aspects of GISFall 2007, 12.11.2007
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
Structure
• Introduction• Overview• Geocoding• Coordinate System• Overlays• Conclusion• Questions
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
Overview
• Announced February 8th, 2005• Beta until October 6th, 2005• Second API version released April 3rd, 2006• Geocoding service added June 11th, 2006• User friendly• Fast• Public available API
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
API Overview
• Cross browser compatible• JavaScript based• Object oriented• Well structured• Extensible• Comprehensive documentation• Key is required
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
Geocoding
• Maps an address to a geographic coordinate• Interpolation method• Limited accuracy• Easy to use• Used technology hidden• Alternatives to Google's Geocoder available
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
The Coordinate System
• Datum: WGS84• Projection: Mercator• Unit system: Pixels• Axes: East, South• Origin: International date line, north pole
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
Mercator Projection
• Projection of the earth onto a cylinder• Invented 1569 by Geradus Mercator• Preserves directions• Distorts the size
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
Tiles and Origin
• Fixed size of 256x256 pixels• 2z tiles per zoom level z• Maximal pixel space: 256 * 219
• Origin shift• Invert y
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
Pros / Cons
• Prerender tiles• Effective caching• Easy implementable• Simple map overlay• Bad accuracy when far north / south• Uncommon
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
Web Map Service
• OGC standard– Map retrieval– Feature information– Map types
• Very flexible• On the fly map generation• Public available map servers
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
Conclusion
• User friendly• Flexible• Great API• Easy to integrate into existing applications• Capable of being extended• Lack of open standards
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
ReferencesElson, J., Howell, J., & Douceur, J. R. (2007). MapCruncher: Integrating the world's geographic information. SIGOPS Oper.Syst.Rev., 41(2), 50-59.
Gibson, R., & Erle, S. (2006). Google maps hacks
Google maps. (2007). Retrieved 12.11.2007, 2007, from http://docs.codehaus.org/display/GEOSDOC/Google+Maps
Google maps deconstructed. (2006). Retrieved 12.11.2007, 2007, from http://cfis.savagexi.com/articles/2006/05/03/google-maps-deconstructed
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
ReferencesOnEarth. (2006). Retrieved 12.11.2007, 2007, from http://wms.jpl.nasa.gov/
Podnar, H., Gschwender, A., Workman, R., & Chan, J. (2006). Geospatial visualization of student population using google\™ maps. J.Comput.Small Coll., 21(6), 175-181.
USGS earth resources observation and science (EROS). (2005). Retrieved 12.11.2007, 2007, from http://gisdata.usgs.gov/
Weisstein, E. W. (2004). Mercator projection. Retrieved 12.11.2007, 2007, from http://mathworld.wolfram.com/MercatorProjection.html
Structure:
Overview
Geocoding
Coordinate System
Overlays
Conclusion
Questions
November 07Computational Aspects of GIS
Oliver Walzer
Analyzing Google Maps
Questions?