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L-03: Datums, Coordinate Systems, Map Projections & Datum Transformations

Location. Location. Location. With so many maps and datums out there, how does a person know what datum is correct? How come my GPS coordinates don't match up on my map? Why is there a shift of 100 metres? How do I transform between different datums? What is a datum? What is the EPSG? Why have GIS Vendors and Oracle adopted them? Does offshore or onshore make a difference? How come there are so many datums? This presentation looks to provide some answers to some of these questions and to point out that latitude and longitude are not absolute.

Over the decades that surveyors have been trying to map the Earth, history and politics have shaped the way we see the world. Are the borders actually there? What if one nation adopts a standard, but the other does not? Does really matter what the co-ordinate system is? Why when I draw the a UTM Projection, the lines are curved, not in a grid? Is the OGC adopting these standards? So many questions and this presentation aims to answer some of them and provide some light on a complicated and sometimes unclear topic.

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Dean C. Mikkelsen, B.Sc., P.Eng., Principal Consultant, Terra ETL Ltd., has consulted and worked overseas in Africa, Europe and the USA within the Oil & Gas industry, Mining, and Forestry industries. He is a Surveying Engineer by trade and has specialized in software, large databases, and geodetic problems. He was a founding member of the America's Petroleum Survey Group in Houston. This group specialized in geodetic problems worldwide as it applied to the E&P industry and was the sister organization to European Petroleum Survey Group (EPSG).

Mr. Mikkelsen is a Principal Consultant with Terra ETL Ltd., a geomatics and Open Source development company that specializes in Internet Mapping, integration with other software and databases, and GIS for Forestry, Mining, Planning, Tourism, Environmental and Oil & Gas. He is registered Professional Engineer with APEGBC.

Frank Warmerdam is an independent geospatial open source software developer, and has been working on the GDAL/OGR library for seven years. Previous to that he was a senior developer at PCI Geomatics for six years. In 1991 he graduated from the University of Waterloo with a Bachelor of Mathematics, majoring in Computer Science. He is also an occasional contributor to many other open source projects, winner of the first annual Sol Katz award, and is currently President of OSGeo.