Call now: (800) 766-1884  


 SQL Server Tips
 SQL Server Training

 SQL Server Consulting
 SQL Server Support
 SQL Server Remote DBA

 SQL Server Scripts
 Scripts Menu





SQL Server xxx

SQL Server Tips by Gama and Naughter Consulting


The Shape of the Earth

The level of the Earth’s oceans, its plains, mountains and valleys, of course defines the true shape of the Earth. Because there is no simple mathematical model to represent this, a concept called a “Geoid” is defined. This is a three dimensional surface defined by mean sea level and its imagined continuation under the continents at the same level of gravitational potential. Because this surface cannot be easily represented mathematically (short of equations with hundreds of terms), other concepts need to be used when calculations need to be performed.

As a first approximation we can consider the shape of the earth as a sphere with a radius of approximately 6400 kilometres (c. 4000 Miles). Because of centrifugal force due to the Earths rotation as well as the fact that the Earth is not a completely solid object, the Earth actually bulges at the Equator and is flattened at the poles. To better model this shape an ellipsoid is normally used. This is a planar ellipse which is rotated around the North / South Polar Axis to form a three dimensional surface. An ellipse in GIS applications is normally represented by the Equatorial Radius, which in mathematical terms is the semi-major axis of the ellipse and a so-called flattening factor, which represents how much the ellipse differs from a circle. During the effort to map the Earth over the last couple of centuries more accurate values for these terms have been obtained as time and technology progresses. Another complication is that different values for these parameters can yield better fits to the Geoid when we restrict over interest to certain regions. Different countries and regions have historically used their own values for the basis of their maps.

The above book excerpt is from:

Super SQL Server Systems
Turbocharge Database Performance with C++ External Procedures

ISBN: 0-9761573-2-2
Joseph Gama, P. J. Naughter





Burleson Consulting Remote DB Administration







Burleson is the America's Team

Note: The pages on this site were created as a support and training reference for use by our staff of DBA consultants.  If you find it confusing, please exit this page.

Errata?  SQL Server technology is changing and we strive to update our SQL Server support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:and include the URL for the page.

Burleson Consulting
SQL Server database support


Copyright © 1996 -  2013 by Vaaltech Web Services. All rights reserved.

Hit Counter