Georeferencing Methodology

This methodology includes analyzing for the correct meter/feet based projection, which is most often not properly stated or not stated at all. This occurs because we often find ourselves working with maps from the EMEA (Europe, Mediterranean, Africa) Region that can be very old. To establish the proper projection parameters requires a literature search and map analysis for information on:

Northing
Easting
Central Meridian
Latitude of Origin
Standard Parallels
Spheroid

On request, after doing this, the map can be re-projected to any other projection or to a Geographic (Latitude/Longitude) WGS84 coordinate system. It is possible to work in the projected state but not all GIS software allows “projection on the fly”.  ESRI products have the ability to do this.  In view of this, one may encounter problems when maps are viewed using other product viewers.

It is sometimes the case that the map only has a GCS (Latitude/Longitude) with no trace of a meter/feet based system in which case we will work within these parameters. Sometimes the distortion of the latitudes and longitudes is not severe (generally small, localized, areas) and the map can be georeferenced directly to this system.

Georeferencing to the original map projection parameters is undoubtedly the best manner in which to georeference and affords the most accuracy. In any discipline science or other; with maps covering large areas, using a meter/feet based projection is the ideal option and should be utilised wherever possible.

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