A computer implemented method for generating a set of data representative of a pixel beam in an object space of a 4D , 4-dimensional, light-field optical acquisition system, a pixel beam being a pencil of rays of light that reaches at least one pixel of a sensor of said 4D light-field optical acquisition system when propagating through an entrance pupil of said 4D light-field optical acquisition system, the pixel beam being represented by a hyperboloid of one sheet supported by two sections, one being the conjugate of said pixel and the other being said entrance pupil, comprising: - generating a set of data representative of the pixel beam by: • computing a first rotation angle of a first straight line describing a surface of said hyperboloid, called first generating ray, around a second straight line being a revolution axis of the hyperboloid, said rotation transforming the first generating ray into a second generating ray crossing a reference straight line, • computing a second rotation angle of a third straight line describing the surface of the hyperboloid, called third generating ray, around the revolution axis of the hyperboloid, said rotation transforming the third generating ray into a fourth generating ray crossing the reference straight line, • computing a distance between one of the second or the fourth generating ray and the revolution axis of the hyperboloid, said set of data comprising the parameters representative of the second generating ray, parameters representative of the fourth generating ray and the distance between one of the second or the fourth generating ray and the revolution axis of the hyperboloid. - generating a set of data representative of the pixel beam by: • computing a first rotation angle of a first straight line describing a surface of said hyperboloid, called first generating ray, around a second straight line being a revolution axis of the hyperboloid, said rotation transforming the first generating ray into a second generating ray crossing a reference straight line, • computing a second rotation angle of a third straight line describing the surface of the hyperboloid, called third generating ray, around the revolution axis of the hyperboloid, said rotation transforming the third generating ray into a fourth generating ray crossing the reference straight line, • computing a distance between one of the second or the fourth generating ray and the revolution axis of the hyperboloid, • computing a first rotation angle of a first straight line describing a surface of said hyperboloid, called first generating ray, around a second straight line being a revolution axis of the hyperboloid, said rotation transforming the first generating ray into a second generating ray crossing a reference straight line, • computing a second rotation angle of a third straight line describing the surface of the hyperboloid, called third generating ray, around the revolution axis of the hyperboloid, said rotation transforming the third generating ray into a fourth generating ray crossing the reference straight line, • computing a distance between one of the second or the fourth generating ray and the revolution axis of the hyperboloid, <EOS>