Depth perception is one of the oldest and most intriguing problems in visual perception. This paper presents four sets of experiments in which the depth effect is induced by motion. Geometrical model depicting amodal percept, created by two mobile dots, was tested in the first two sets of experiments. The dots were presented on a CRT screen and the percept was quantified. The length and the angle of inclination were measured. Four factors were varied in the experiments: 1) length of an amodal rod, 2) its angle of inclination, 3) shape of the rod’s paths and 4) angle of inclination of the plains which contained the paths. All of the factors were statistically significant confirming proposed geometrical model. A full mobile line was a stimulus in the other two sets of experiments. The end points of the line moved on the same paths as the mobile dots from the first two sets of experiments. According to geometry the line should not provide more information than the mobile dots. Nevertheless perceptually the line and the dots were not identical: there was a significant difference on all four varied factors. Consequently the geometrical model can not be applied to this type of stimuli.