It is pointed out that more than one temporal and spatial distribution of director angles can be obtained from the interference patterns (varying in space and time) of transmitted polarized (monochromatic and white) light from liquid crystals. When specific physical conditions (e.g. the time variation of the local velocities of nonlinear waves described by shearing director equation of soltons) are taken into account, the above uncertainty can be removed. Detailed discussions on the case of solitons in shearing nematics are given. Numerical calculations show that the spatial distribution of director angles given in Eef. 5 is in contradiction to the directions of velocities of the three dark lines (under white light) observed experimentally if the one-dimensional shearing director equation of solitons is assumed. A distribution of director angles in better agreement with experiments is given.