Projection for Louisiana
Projections enable the curved earth's surface to be depicted on a flat surface such as the computer monitor. This process of flattening the curved surface inherently results in distortion. Three categories of projections are equivalent, conformal, and compromise. Equivalent projections attempt to minimize the distortion of area, so that areas of small regions are best represented. Conformal projections attempt to minimize the distortion of shape, so that shapes of small regions are best represented. Compromise projections attempt to better show BOTH area and shape, but distort both properties.
Web maps commonly use the geographic projection or Plate Carrée projection that simply uses the latitude and longitude coordinates as a rectangular grid. It greatly distorts the shape and area displayed and is inappropriate for showing spatial distributions.
Recognizing that most viewers of environmental maps are seeking to explore spatial relationship between features on the earth's surface, the most appropriate projection would be an equivalent projection, one that exhibits equal area properties and displays the relative density of the features reasonably well. An Albers Equal Area Projection derived from the USA Contiguous Albers Equal Area Projection supplied by ESRI was adjusted to fit the State. The criteria are shown below:
The datum is the North American Datum 1983 (NAD 83).
Data available for download are supplied unprojected or as Plate Carrée.