Structure: Overview Geocoding Coordinate System Overlays Conclusion Questions November 07 Computational Aspects of GIS Oliver Walzer Analyzing Google Maps Analyzing Google Maps Oliver Walzer Computational Aspects of GIS Fall 2007, 12.11.2007
Jan 08, 2018
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?