The Elastic Fitter is a modification of the Elastic Arms algorithm of Ohlsson, Peterson, and Yuille [15,16]. A full description and justification requires its own report and for this see [17].
The fitter is basically a fancy time fitter with a minimisation that uses a simulated annealing technique and a very nice method for ignoring noise/reflection hits as the fit proceeds. There is also a direction fit which is carried out along with the position fit.