Automatic process of predictive determination implemented by software, in the form of a digital simulation, of the position and movements of the skin of a human subject or an animal in an area of interest located at the level of the thorax and/or the abdomen, with said subject preferably being stretched out on their back and breathing freely or in an assisted manner, said process comprising, in a preliminary manner, acquiring or determining multiple positions and configurations of the profile of the skin in predetermined, consecutive, axial planes that are essentially perpendicular to the craniocaudal axis and distributed along this axis at determined locations, at given successive times, in different respiratory positions, advantageously during inhalation and exhalation phases of the subject, the process further comprising, - during a preliminary treatment phase, constructing at least one independent deformable digital model of the profile of the skin in each axial plane (Pa) from data pertaining to different skin profiles that are acquired or determined previously, - then noting, in a repetitive manner, the actual position of a point or a specific point area on the skin of the subject at the level of each of the aforementioned axial planes (Pa), whose position is modified in a significant manner during the inhalation and exhalation phases, and - providing, essentially in real time, on the one hand, a simulation of the profile of the skin in each axial plane (Pa), as a function of the actual position noted for each point or specific point area and by exploiting the deformable digital model of the skin profile in the corresponding plane (Pa), and, on the other hand, an evolving three-dimensional representation of the skin at the level of the area of interest, this on the basis of a three-dimensional model for overall simulation of the skin composed of the plurality of deformable and independent elementary two-dimensional axial models established in the axial planes (Pa) and by interpolation between said different aforementioned axial planes (Pa), the process being characterised in that each deformable digital model of a skin profile, respectively associated with one of the predetermined axial planes (Pa), is obtained by pairing points in an essentially radial direction, in the axial plane (Pa) in question, between at least two shapes or configurations that are significantly different from the curve of the skin profile, corresponding to at least two different respective states of the respiratory movement of the subject. - during a preliminary treatment phase, constructing at least one independent deformable digital model of the profile of the skin in each axial plane (Pa) from data pertaining to different skin profiles that are acquired or determined previously, - then noting, in a repetitive manner, the actual position of a point or a specific point area on the skin of the subject at the level of each of the aforementioned axial planes (Pa), whose position is modified in a significant manner during the inhalation and exhalation phases, and - providing, essentially in real time, on the one hand, a simulation of the profile of the skin in each axial plane (Pa), as a function of the actual position noted for each point or specific point area and by exploiting the deformable digital model of the skin profile in the corresponding plane (Pa), and, on the other hand, an evolving three-dimensional representation of the skin at the level of the area of interest, this on the basis of a three-dimensional model for overall simulation of the skin composed of the plurality of deformable and independent elementary two-dimensional axial models established in the axial planes (Pa) and by interpolation between said different aforementioned axial planes (Pa),