At execution of smoothing procedure numbers of neighboring zones are not calculated anew but d are calculated by addition to components translating the number of the central zone into number of one of 27 adjacent zones (3x3x3). These components are calculated beforehand. The logic of their evaluation is defined by logic of an evaluation of common linear number of an element (zone) in a multivariate (three-dimensional) array.
To reduce number of contiguous segments tracing a reference contour at build-up of its hypogram, the next reference hypogram points are under construction on a forward branch of last contiguous segment. It is possible to tell, that on this branch the fictitious tangential contiguous segment moves ahead, and in its frame positions of the basis vector are registered. The boundary of such construction is defined by mismatch of positions of the basis vector in frames of actual and fictitious segments. Thus a movement step of actual segments is continuously arranged with the help of feed-back so that to keep the mismatch value within the limits of a zone quarter, and a step of fictitious segments have to keep adjacent points of the reference hypogram within the limits of one zone. The zone, as well as earlier, is meant as an element of subdivision of parametrical space. If it is not possible to be made, it is accepted, that in this place the hypogram has a rupture and its construction proceeds from other place of the standard contour.