Real-world occlusion in optical see-through AR displays

In this work we describe a system composed by an optical see-through AR headset---a Microsoft HoloLens---, stereo projectors and shutter glasses. Projectors are used to add to the device the capability of occluding real-world surfaces to make the virtual objects to appear more solid and less transparent. A framework was developed in order to allow us to evaluate the importance of occlusion capabilities in optical see-through AR headset. We designed and conducted two experiment to test whether making virtual elements solid would improve the performance of certain tasks with an AR system. Results suggest that making virtual objects to appear more solid by projecting an occlusion mask onto the real-world is useful in some situations. Using an occlusion mask it is also possible to eliminate ambiguities that could arise when enhancing user's perception in some ways that are not possible in real-life, like when a "x-ray vision" is enabled. In this case we wanted to investigate if using an occlusion mask to eliminate perceptual conflicts will hit user's performance in some AR applications. The framework that allowed us to conduct our experiments is made freely available to anyone interested in conducting future studies.