The Georgia Institute of Technology is conducting research on Human Identification at a Distance, with an emphasis on gait recognition. Supported by the Defense Advanced Research Projects Agency (DARPA), the project's development of gait recognition systems and algorithms is "an example of an activity-specific biometric: a method of extracting some identifying properties of an individual or of an individual's behavior that is only applicable when a person is performing that specific action." Several research papers, experiment descriptions, and data sets are available on the project's homepage. Some of links to the display software and subject data appear to be inoperative, however. A small number of related papers are also provided, addressing the topics of Facial Modeling and Activity Specific Background Subtraction.