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AR / VR HoloLens

Benefits and Parameters of Shadow in Augmented Reality-Environments, Part 2

In the previous blog post of this short series, I described the findings of my study Benefits and Parameters of Shadow in Augmented Reality-Environments on how shadow influences the perception of height (distance to the floor) in Augmented Reality environments. Before we get to a possible solution for Mixed Reality Scenarios with Microsoft HoloLens, let’s take a look at more interesting results of the study.

Estimation of Depth

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.

During this experiment, participants of the study were presented with two spheres that varied in size and depth. In random order, every scene was presented twice – once with shadows present, once without shadows.

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Image Processing

20 – 30% Better JPEG compression from Google? My Test Results.

The blog post from Google sounds intriguing – 20% to 30% better JPEG image compression at the same visual quality through the Guetzli encoder. That has potential for a huge speed increase of websites.

While there are of course a lot of other better image formats around than JPEG (e.g., WebP or JPEG 2000), time has shown that it’s more or less impossible for them to gain any traction. It’s a pity, but on the other hand ensures that pretty much every device available on the market right now can load and show all websites.

Testing Guetzli!

To check the new Guetzli JPEG encoder out myself, I downloaded the binary executable of v1.0 and put it through some very quick tests.

Continue reading “20 – 30% Better JPEG compression from Google? My Test Results.”
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AR / VR HoloLens

Benefits and Parameters of Shadow in Augmented Reality-Environments, Part 1

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.

Study on Shadow in Augmented Reality

To get exact numbers and to better understand the situation, I’ve written my Bachelor Thesis “Benefits and Parameters of Shadow in Augmented Reality-Environments” in 2004. Even though back then the study was done with marker-based Augmented Reality, the general setting is comparable to scenes created with HoloLens.

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.

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AR / VR HoloLens Windows

How to create Photos of HoloLens in Use

Screenshots taken with HoloLens are often difficult to comprehend, as they only show the scene as seen by the user, but not the user itself. How is he interacting with the scene, where is he standing in relation to the view?

Therefore, photos of HoloLens apps usually show a 3rd person view. Getting a real live transmission of the 3D objects seen by a HoloLens user works with the new Spectator View by Microsoft. However, setting that up is tricky: you need 2 HoloLenses, some special hardware and in the ideal case a 3D printed mount.

A simpler approach for a still screen is to take a photo with a good quality camera, and then to render the scene with matching perspective.

Unity itself is not directly suited to rendering a scene to an image, and it also lacks some of the advanced tools to align the 3D scene with a photo.

Here, I’ll describe an approach to use 3ds Max to simulate the view of a HoloLens user in 3rd person view. I used this for our PalKranHoloPlan AR8000 project, which we created during the Palfinger Hackathon.

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