Source Software News

PE03257A.gif (4096 bytes)IMPORTANT NEWS!!

In order to simplify the distance calculations between two points our Zip Source U.S. product converts conventional latitude/longitude measures into X and Y coordinates. This conversion simplifies distance calculations for our customers by allowing them to utilize a basic formula - the Pythagorean theorem - for calculating point to point distances instead of the more complicated Great Circle distance calculation formulas.

It is our goal to provide you with the most complete and accurate set of geographic data possible. Towards this end we recently completed an in depth review of the quality of the latitude/longitude data contained within Zip Source U.S. The results of this review indicated that the calculations we use to convert latitude/longitude to X Y coordinates could be modified to provide an even higher level of accuracy in calculating point to point distances. In order to further minimize the distortion which occurs when a curved surface is represented on a flat plane (via X Y coordinates) we have chosen to convert from a Lambert Polyconic projection to an Albers projection to generate the X Y coordinates contained in Zip Source U.S.

We are pleased to announce that beginning with the June 1996 update, Zipsource contains the most accurate set of X Y coordinates in the product's history! The format of the file will not change. However, each coordinate will change since we are using a different set of calculations. The new set of coordinates has no relation to any previous sets of coordinates. It is important to remember this if you have programs that simply compare old coordinates to new ones and flag any changes. We believe that most changes in distance will be slight with the greatest changes being realized on long distance calculations.

We trust that this change will afford you the ability to provide your customers with an even higher level of accuracy in their distance calculations.

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