The human visual system can perceive 3-D information of an object by using disparity between two eyes, gradient of illumination (shading), occlusion, textures and their perspective and so on. Consequently, the disparity and the occlusion observed with binocular viewing seems to be the most important cues to get 3-D information. For the artificial realization of the visual function such as in computer vision or robot vision system, it seems to be a clever way to learn from the human visual mechanism. Recently, the author found a new type of illusion. When the visual stimuli of disparity are given only partially along the contour of an object, human visual system can perceive the 3-D surface (not only plane but also curved) of the object where there are no physical visual stimuli to get depth information. The interactions between the perceived illusory surface (occlusion, intersection and transparency) can be recognized. These newly found illusory phenomena have close relations with the visual function of 3-D space perception and can provide a new paradigm in the field of computer vision and human interface.