The orientational distribution function for polymer chain segments in plain-strain compressed glassy poly(methyl methacrylate) is evaluated, as a function of two polar angles, from a series of one-dimensional deuterium NMR spectra. The experimental data are analyzed using a tailored regulatory approach. For low degrees of orientational order, the choice of the regularization scheme is shown to become critical and two-dimensional Tikhonov-Phillips regularization yielded the best results for the present study.