A HoloArticle

Here is an update on my quest to stay on top of all things “holo:” HoloLamp and RealView “Live Holography.” While the two have really nothing to do with each other, both claim the “holo” label with varying degrees of legitimacy, and happened to pop up recently.


At its core, HoloLamp is a projection mapping system somewhat similar to the AR Sandbox, i.e., a combination of a set of cameras scanning a projection surface and a viewer’s face, and a projector drawing a perspective-correct image, from the viewer’s point of view, onto said projection surface. The point of HoloLamp is to project images of virtual 3D objects onto arbitrary surfaces, to achieve effects like the Millenium Falcon’s holographic chess board in Star Wars: A New Hope. Let’s see how it works, and how it falls short of this goal.

Creating convincing virtual three-dimensional objects via projection is a core technology of virtual reality, specifically the technology that is driving CAVEs and other screen-based VR displays. To create this illusion, a display system needs to know two things: the exact position of the projection surface in 3D space, and the position of the viewer’s eyes in the same 3D space. Together, these two provide just the information needed to set up the correct perspective projection. In CAVEs et al., the position of the screen(s) is fixed and precisely measured during installation, and the viewer’s eye positions are provided via real-time head tracking.

As one goal of HoloLamp is portability, it cannot rely on pre-installation and manual calibration. Instead, HoloLamp scans and creates a 3D model of the projection surface when turned on (or asked to do so, I guess). It does this by projecting a sequence of patterns, and observing the perspective distortion of those patterns with a camera looking in the projection direction. This is a solid and well-known technology called structured-light 3D scanning, and can be seen in action at the beginning of this HoloLamp video clip. To extract eye positions, HoloLamp uses an additional set of cameras looking upwards to identify and track the viewer’s face, probably using off-the-shelf face tracking algorithms such as the Viola-Jones filter. Based on that, the software can project 3D objects using one or more projection matrices, depending on whether the projection surface is planar or not. The result looks very convincing when shot through a regular video camera:

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Remote Collaborative Immersive Visualization

I spent the last couple of days at the first annual meeting of “The Higher Education Campus Alliance for Advanced Visualization” (THE CAAV), where folks managing or affiliated with advanced visualization centers such as KeckCAVES came together to share their experiences. During the talks, I saw slides showing Vrui‘s Collaboration Infrastructure pop up here and there, and generally remote collaboration was a big topic of discussion. During breaks, I showed several people the following video on my smartphone (yes, I finally joined the 21st century), and afterwards realized that I had never written a post about this work, as most of it predates this blog. So here we go.

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On the road for VR: Redwood City, California

Last Friday I made a trek down to the San Francisco peninsula, to visit and chat with a couple of other VR folks: Cyberith, SVVR, and AltspaceVR. In the process, I also had the chance to try a couple of VR devices I hadn’t seen before.

Cyberith Virtualizer

Virtual locomotion, and its nasty side effect, simulator sickness, are a pretty persistent problem and timely topic with the arrival of consumer VR just around the corner. Many enthusiasts want to use VR to explore large virtual worlds, as in taking a stroll through the frozen tundra of Skyrim or the irradiated wasteland of Fallout, but as it turns out, that’s one of the hardest things to do right in VR.

Figure 1: Cyberith Virtualizer, driven by an experienced user (Tuncay Cakmak). Yes, you can jump and run, with some practice.

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On the Road for VR: Augmented World Expo 2015, Part I: VR

I attended the Augmented World Expo (AWE) once before, in 2013 when I took along an Augmented Reality Sandbox. This time, AWE partnered with UploadVR to include a significant VR subsection. I’m going to split my coverage, focusing on that VR component here, while covering the AR offering in another post.

eMagin 2k×2k VR HMD

eMagin’s (yet to be named) new head-mounted display was the primary reason I went to AWE in the first place. I had seen it announced here and there, but I was skeptical it would be able to provide the advertised field of view of 80°×80°. Unlike Oculus Rift, HTC/Valve Vive, or other post-renaissance HMDs, eMagin’s is based on OLED  microdisplays (unsurprisingly, with microdisplay manufacture being eMagin’s core business). Previous microdisplay-based HMDs, including eMagin’s own Z800 3DVisor, were very limited in the FoV department, usually topping out around 40°. Magnifying a display that measures around 1cm2 to a large solid angle requires much more complex optics than doing the same for a screen that’s several inches across.

Figure 1: eMagin’s unnamed 2k x 2k, 80×80 degree FoV, VR HMD with flip-up optics.

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On the road for VR: Silicon Valley Virtual Reality Conference & Expo

Yesterday, I attended the second annual Silicon Valley Virtual Reality Conference & Expo in San Jose’s convention center. This year’s event was more than three times bigger than last year’s, with around 1,400 attendees and a large number of exhibitors.

Unfortunately, I did not have as much time as I would have liked to visit and try all the exhibits. There was a printing problem at the registration desk in the morning, and as a result the keynote and first panel were pushed back by 45 minutes, overlapping the expo time; additionally, I had to spend some time preparing for and participating in my own panel on “VR Input” from 3pm-4pm.

The panel was great: we had Richard Marks from Sony (Playstation Move, Project Morpheus), Danny Woodall from Sixense (STEM), Yasser Malaika from Valve (HTC Vive, Lighthouse), Tristan Dai from Noitom (Perception Neuron), and Jason Jerald as moderator. There was lively discussion of questions posed by Jason and the audience. Here’s a recording of the entire panel:

One correction: when I said I had been following Tactical Haptics‘ progress for 2.5 years, I meant to say 1.5 years, since the first SVVR meet-up I attended. Brainfart. Continue reading

On the road for VR: Microsoft HoloLens at Build 2015, San Francisco

I have briefly mentioned HoloLens, Microsoft’s upcoming see-through Augmented Reality headset, in a previous post, but today I got the chance to try it for myself at Microsoft’s “Build 2015” developers’ conference. Before we get into the nitty-gritty, a disclosure: Microsoft invited me to attend Build 2015, meaning they waived my registration fee, and they gave me, like all other attendees, a free HP Spectre x360 notebook (from which I’m typing right now because my vintage 2008 MacBook Pro finally kicked the bucket). On the downside, I had to take Amtrak and Bart to downtown San Francisco twice, because I wasn’t able to get a one-on-one demo slot on the first day, and got today’s 10am slot after some finagling and calling in of favors. I guess that makes us even. 😛

So, on to the big question: is HoloLens real? Given Microsoft’s track record with product announcements (see 2009’s Project Natal trailer and especially the infamous Milo “demo”), there was some well-deserved skepticism regarding the HoloLens teaser released in January, and even the on-stage demo that was part of the Build 2015 keynote:

The short answer is: yes, it’s real, but… Continue reading

What is holographic, and what isn’t?

Microsoft just announced HoloLens, which “brings high-definition holograms to life in your world.” A little while ago, Google invested heavily in Magic Leap, who, in their own words, “bring magic back into the world.” A bit longer ago, CastAR promised “a magical experience of a 3D, holographic world.” Earlier than that, zSpace started selling displays they used to call “virtual holographic 3D.” Then there is the current trailblazer in mainstream virtual reality, the Oculus Rift, and other, older, VR systems such as CAVEs.

Figure 1: A real person next to two “holograms,” in a CAVE holographic display.

While these things are quite different from a technical point of view, from a user’s point of view, they have a large number of things in common. Wouldn’t it be nice to have a short, handy term that covers them all, has a well-matching connotation in the minds of the “person on the street,” and distinguishes these things from other things that might be similar technically, but have a very different user experience?

How about the term “holographic?” Continue reading

On the road for VR: Silicon Valley Virtual Reality Conference & Expo

I just got back from the Silicon Valley Virtual Reality Conference & Expo in the awesome Computer History Museum in Mountain View, just across the street from Google HQ. There were talks, there were round tables, there were panels (I was on a panel on non-game applications enabled by consumer VR, livestream archive here), but most importantly, there was an expo for consumer VR hardware and software. Without further ado, here are my early reports on what I saw and/or tried.

Figure 1: Main auditorium during the “60 second” lightning pitches.

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Someone at Oculus is Reading my Blog

I am getting the feeling that Big Brother is watching me. When I released the inital version of the Vrui VR toolkit with native Oculus Rift support, it had magnetic yaw drift correction, which the official Oculus SDK didn’t have at that point (Vrui doesn’t use the Oculus SDK at all to talk to the Rift; it has its own tracking driver that talks to the Rift’s inertial movement unit directly via USB, and does its own sensor fusion, and also does its own projection setup and lens distortion correction). A week or so later, Oculus released an updated SDK with magnetic drift correction.

A little more than a month ago, I wrote a pair of articles investigating and explaining the internals of the Rift’s display, and how small deviations in calibration have a large effect on the perceived size of the virtual world, and the degree of “solidity” (for lack of a better word) of the virtual objects therein. In those posts, I pointed out that a single lens distortion correction formula doesn’t suffice, because lens distortion parameters depend on the position of the viewers’ eyes relative to the lenses, particularly the eye/lens distance, otherwise known as “eye relief.” And guess what: I just got an email via the Oculus developer mailing list announcing the (preview) release of SDK version 0.3.1, which lists eye relief-dependent lens correction as one of its major features.

Maybe I should keep writing articles on the virtues of 3D pupil tracking, and the obvious benefits of adding an inertially/optically tracked 6-DOF input device to the consumer-level Rift’s basic package, and those things will happen as well. 🙂

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More on Desktop Embedding via VNC

I started regretting uploading my “Embedding 2D Desktops into VR” video, and the post describing it, pretty much right after I did it, because there was such an obvious thing to do, and I didn’t think of it.

Figure 1: Screenshot from video showing VR ProtoShop run simultaneously in a 3D environment created by an Oculus Rift and a Razer Hydra, and in a 2D environment using mouse and keyboard, brought into the 3D environment via the VNC remote desktop protocol.

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