A major component of the MaNIS, HerpNET, ORNIS and FishNet II projects is to add georeferenced coordinates to specimen data. Most museum specimens were collected before global positioning systems (GPS) were widely available to the public, therefore the geospatial information associated with the collection of an animal or plant specimen is stored in the associated field notes. Collectors take great care to describe where they were when they found an animal, so others would be able to trace their footsteps and return to the exact same place in the field. Often collectors travelled to remote locations with few man-made landmarks to reference, therefore researchers are needed to 'retrospectively georeference' the collector's field notes.
Uncertainty in science gets a bad rap. In fact, it can be extremely useful in evaluating the quality and appropriateness of the data for use. When presented with a set of coordinates, the point may plot in the center of a county. Was the specimen actually found in the center of the county, or was the county name the only information in the locality description? A measure of uncertainty, called MaxErrorDistance in Darwin Core 2 schema, is a length measurement that represents the radius of the circle around the coordinates. This measurement can help users evaluate whether the data are precise enough for their study or model.
The projects under VertNet use the point radius method of georeferencing as described in the Guide to Best Practices for Georeferencing. This outlines a standard protocol with an in-depth discussion of the methods for interpreting different locality types geographically and for determining an measure of uncertainty. The MaNIS, HerpNET, ORNIS (MHO) Georeferencing Guidelines are a condensed version of this document as it applies directly to the VertNet projects. Georeferencing for Dummies (pdf) organizes all of this information in an easy to read guide with specific instructions on how to use the Error Calculator.
For a list of documents, online resources and GIS data, see the HerpNET Georeferencing Resources.