In mixed reality using video see-through displays, various optical effects can be simulated for representing a transparent object. However, consumer-available OST-HMDs can not reproduce some of their effects correctly because of its mechanism. There has been little discussion concerning to what extent such transparent objects can be represented realistically. In this demonstration, we will show how effective each for combination of existing methods is.

Virtual shadows provide important cues to determine the positional relationship between virtual objects and a real scene. However, it' s difficult to render shadows in the real scene on optical see-through head-mounted displays without occlusion-capability. In the previous work, we cast virtual shadows not with physical light attenuation but with brightness induction caused by virtual objects, referred to as shadow inducers, which surround the shadow area to gradually amplify the intensity of the real scene pattern [4]. However, because the shadow inducer was prepared beforehand, the shape of the shadow is constant, the real scene shadowing is limited to a flat surface, and a large of viewpoint change is impossible. In this demonstration, we propose a method to generate shadow inducers in real time that can change the shape of virtual objects and the viewpoint of users. In this method, depending on the appearance of shadows, the surrounding luminance is gradually amplified with the difference of gaussian (DOG) representing characteristics of human vision. Users can observe shadows of moving and deforming virtual objects on a real tabletop and other non-planar objects.

This paper proposes a novel method for casting virtual shadows on real surfaces on an optical see-through head-mounted display without any extra physical filter devices. Instead, the method presents shadows as results of brightness induction. To produce brightness induction, we place a texture of the real scene with a certain transparency around the shadow area to amplify the luminance of the surrounding area. To make this amplification unnoticeable, the transparency of the surrounding region is gradually increased as the distance from the shadow region. In the experiment with 23 participants, we confirmed that users tend to perceive the shadow region is darker than a non-shadow area under the conditions where a circular virtual shadow is placed on a flat surface.