Augmented reality is in a transitional phase, and there are a few interesting problems that prevent the technology from overlaying digital information precisely enough over the physical world to be useful in situations where precision is tantamount to success. Motion-to-photon latency is one such vexing issue. This occurs on inside-out tracking AR headsets such as the Microsoft HoloLens. To offset latency to indiscernible levels, a technique known as visual-inertial fusion must be incorporated into the user experience. This is no easy task.
Besides improving latency, decreasing transparency of virtual objects seen in augmented reality is another difficult challenge faced by AR headset developers. Specific situations where AR would be useful, such as surgery, require the use of bright light. The bright light causes the solidity of virtual objects to fade in a similar manner to traditional projections on a screen.
A group of AR researchers recently developed a promising system to combat this abundance of transparency. In a paper titled Factored Occlusion: Single Spatial Light Modulator Occlusion-capable Optical See-through Augmented Reality Display, researchers describe the importance of the depth-perceptual phenomenon known as occlusion, where objects in the foreground block light from objects in the background. According to the paper, “…failure to emulate occlusion not only detracts from perceptual realism, but could be dangerous, inducing user error in tasks involving spatial judgment.”
Commercial AR headsets do not possess high-performance occlusion since they use a single spatial light modulator (SLM) to generate virtual objects.
Instead of adding another SLM to improve occlusion, these researchers created a special array of miniature mirrors that change positions thousands of times per second to imbue digital objects with more solidity. The mirrors alternatively let natural light in and deflect light out. When they change positions to let light out, an artificial light source from within their system is activated.
Bottom Line
Some challenges still exist with the new occlusion system, including rendering colors correctly. The system also requires more computing power, which means it draws more power. This trade-off would make untethered AR headsets less feasible and might in fact add bulk to the headsets in a different form than the addition of another spatial light modulator.