Simply put, Geocoding is the process of assigning a set of coordinate pairs (combined to create points, lines or polygons) that describe the locality of some object or phenomenon. The most familiar form of geocoding is performed when you enter an address into Google Maps, MapQuest or other online street mapping platform, and a point on a map is returned to you. However, street addresses are not the only locality types that are subject to the geocoding process. Localities referring to various administrative boundary levels (state, district, province, postal code) and even localities with varying levels of specificity (directional offsets from known locations, distances along paths, etc...) can be geocoded and, importantly, qualified with some level of geometric uncertainty. In the research context, geocoding is generally done as a batch process, though it is generally an iterative one, requiring some manual quality control and fine-tuning for best results. The resources and tools listed here are those that I have found useful in various types of geocoding processes.
The Herpnet Georeferencing and GIS Links List
A collection of geocoding and GIS links relevant to the process of geocoding, with particular emphasis upon the process of geocoding localities that refer to specimens held within Natural History Collections. The resources are also quite useful for the geocoding and calculation of uncertainties associated with localities that refer to objects and phenomena in many other disciplines.
MaNIS/HerpNet/ORNIS Georeferencing Guidelines
This document contains information about assigning geographic coordinates, and maximum error distances for those coordinates, to locality descriptions.
Darwin Core Terms: A quick reference guide (Location)
The metadata standard adopted for the recording of information about Natural History and Biodiversity collections. Of particular interest to those involved in larger, and ongoing, geocoding projects are the "Location Terms." The DarwinCore location schema represents an excellent framework for recording location and associated uncertainties in nearly any terrestrial discipline.
HerpNET's "Georeferencing for Dummies" (*.xls)
An fantastic resource, providing guidelines for geocoding of 25 distinct types of locality (Named Place, Offset at Heading, Between Two Places, etc...). Specific procedures for determining the Extent and associated Error of textual locality descriptions.
A platform for georeferencing textual locality descriptions (all those listed in the HerpNET "Dummies" guide) developed and maintained by the Tulane University Museum of Natural History. Multiple platforms, including a Web Client, Embeddable Web Client, Desktop Client, Java Client and numerous web services against which custom applications can be developed. Also provided a collaborative interface that allows management of team geocoding.
The Georeferencing Calculator
A tool for calculating the coordinate location Maximum Error for text based localities. Also available in Spaninsh.
Manual for the Georeferencing Calculator
Guide to the use of the MaNIS/HerpNet/ORNIS Georeferencing Calculator for georeferencing of descriptive localities such as those found in museum-based natural history collections.