Digital Healthcare, Augmented Reality, Mobile Apps and more! Andreas Jakl is a lecturer for Digital Healthcare & Smart Engineering @ St. Pölten University of Applied Sciences, Microsoft MVP for Windows Development and Amazon AWS Educate Cloud Ambassador.
Shadows are immensly important for the perception of Augmented Reality scenes. If the holographic 3D object that is placed in the real world has a shadow, it fits better to the world, and users have a better understanding of its placement in the world. This is the result of the study I’ve done some time ago, detailled in the blog posts: Part 1, Part 2, Part 3. How to apply this to Microsoft HoloLens? Negative Shadows are the answer.
HoloLens and Holographic Shadows?
For the HoloLens, rendering shadows is special. The HoloLens displays are light-based – as such, they can add light to a real-world scene. However, they cannot reduce light or darken parts of the real world. If you add a traditional dark shadow to a scene, it simply won’t be visible in the HoloLens. Continue reading “How to add Negative Shadows to a HoloLens Scene”
In the last part of the short blog series, we will take a quick look at the required realism of shadow in Augmented Reality scenarios. Is shadow detail crucial for user acceptance?
Read part 1 for an introduction and how shadow influences the estimation of height, and part 2 for more on estimation of depth and light position.
Required Detail of Shadows
The HoloLens is essentially a head-worn, battery-powered PC. As such, the computing capacity is of course much less compared to most virtual reality systems like the HTC Vive or Oculus Rift where a full-blown PC with a power consumption of around 600 W is rendering the scenes.
Many games use highly simplified shadows that are only a very crude approximation of what a real shadow should look like. In this experiment, the aim was to examine how much simplification of volumentric shadows is accepted by subjects.
To correctly percieve a mixed reality scene, the user also has to judge the depth (distance to the camera) of a virtual 3D object in a real scene. If the perception is off, it can destroy the mixed reality effect. In some applications where accuracy is vital, wrong perception of depth can have even more severe implications.
Usually, holograms placed in real environments through Microsoft HoloLens do not have a shadow. This is mainly due to technical reasons of the HoloLens display, as I’ll discuss in a later blog post.
However, for the scene perception and to correctly determine the holographic object position in the real-world 3D space, as well as for the “feeling” that the scene looks real, shadow is of tremendous importance.
Using an experimental approach, 23 participants were tasked with conducting tests and filling out a questionnaire, judging different AR situations. The tool to create the AR scenes was ShadowAReality by Stephan Drab et. al.
Why Shadow is Important for AR
Literature research showed that shadows are of significant importance for realistic perception. They allow a correct estimation of the placement of objects in the virtual direction, as well as the distance to the camera. Furthermore, shadow defines the volume of the object. Overall, shadows contain a big amount of additional information, which obviously lacks if shadows are missing. They play an important role in how realistic a scene looks.Continue reading “Benefits and Parameters of Shadow in Augmented Reality-Environments, Part 1”