1. A method for determining a self-motion of a vehicle in a surrounding environment, comprising: recording a plurality of snapshots of at least part of the environment by an imaging device fixed in a selected position on the vehicle; analyzing at least two snapshots for determining optical flows of image points, wherein reference points that appear to be stationary from the point of view of the imaging device are ascertained from the optical flows, and wherein the reference points are grouped in an observed set; and dynamically changing the observed set, wherein new reference points are dynamically added to the observed set with the aid of a first predetermined algorithm, and existing reference points are dynamically removed from the observed set with the aid of a second predetermined algorithm, and wherein the second predetermined algorithm includes at least one step for ascertaining permanently present reference points having unchanged positions.