1. An installation for measuring at least one characteristic angle of an anatomical segment, said characteristic angle being representative of the posture of an individual placed in a measurement space of the installation, said characteristic angle also being associated with at least one anatomical point of the individual presenting three-dimensional coordinates in the measurement space, by using a plurality of plane images of the measurement space, each taken by a detector device adapted to detect visible electromagnetic radiation coming from the measurement space, each plane image including a representation of said anatomical segment, said plurality of plane images being distinct in pairs, said installation having a measurement computer system comprising: an identification system suitable for identifying on a plane image a region of interest containing said anatomical point of the individual; a pairing system adapted to determine on each plane image, two-dimensional coordinates of a representation of the anatomical point by searching for correlation between the region of interest and a corresponding zone on each other image; a relationship between a geometrical measurement on each plane image and a magnitude in the measurement space, said relationship being previously established during a step of calibrating the measurement installation; a calculation unit adapted to determine the presented three-dimensional coordinates of said anatomical point of the individual in the measurement space on the basis of said two-dimensional coordinates determined by the pairing system, and of said relationship, and determine said characteristic angle of the anatomical segment; and an anatomical model of the segment, said anatomical model comprising at least one model anatomical point corresponding to the anatomical point of the individual, said identification system being adapted to identify on a plane image said region of interest by using said anatomical model and processing by searching for contrast in said plane image, said measurement installation being adapted to further compare said characteristic angle of said anatomical segment to a corresponding angle of a standard anatomical model in the same posture, in order to identify at least one angle difference between said characteristic angle of the individual and the angle of the standard anatomical model.