1. A non-transitory computer-readable medium having instructions executable by a processor for performing a method comprising: computing phase for signals of each of a plurality of nodes on a geometric surface region associated with tissue of a patient, a subset of the nodes surrounding a given node of the plurality of nodes defining neighboring nodes of the given node; analyzing the computed phase of the given node relative to the phase of each of a set of neighboring nodes of the given node over an activation time period associated with the given node; determining if the given node is a focal point based on the analyzing; and repeating the computing, analyzing and determining for each node of at least a substantial portion of the plurality of nodes to provide focal point data specifying a spatial location corresponding to each detected focal point for the geometric surface region.