Author Archives: okreylos

About okreylos

I am a research computer scientist at the University of California, Davis. My research areas are scientific visualization, particularly in immersive ("virtual reality") environments, human/computer interaction in immersive environments, and 3D computer graphics. My primary work is software development, from architecture over design to implementation and coding. I am the primary software developer for the UC Davis W.M. Keck Center for Active Visualization in the Earth Sciences (KeckCAVES). Some of my released packages are Vrui (a VR development toolkit), CollaborationInfrastructure (a tele-collaboration plug-in for Vrui), Kinect (a driver suite to capture 3D video from Microsoft Kinect cameras), LiDAR Viewer (a visualization package for very large 3D point clouds), 3D Visualizer (a system for interactive visual analysis of 3D volumetric data), Nanotech Construction Kit (an interactive molecular design program), and SARndbox (an augmented reality sandbox). I also dabble in VR hardware, in the sense that I take existing custom or commodity hardware components (3D TVs, head-mounted displays, projectors, tracking systems, Wiimotes, Kinect cameras, ...) and build fully integrated immersive environments out of them. This includes a fair share of driver development to support hardware that either doesn't have drivers, or whose vendor-supplied drivers are not up to par.

This is a post about Vrui

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I just released version 3.0 of the Vrui VR toolkit. One of the major new features is native support for the Oculus Rift head-mounted display, including its low-latency inertial 3-DOF (orientation-only) tracker, and post-rendering lens distortion correction. So I thought it’s time for the first (really?) Vrui post in this venue.

What is Vrui, and why should I care?

Glad you’re asking. In a nutshell, Vrui (pronounced to start with vroom, and rhyme with gooey) is a high-level toolkit to develop highly interactive applications aimed at holographic (or fully-immersive, or VR, or whatever you want to call them) display environments. A large selection of videos showing many Vrui applications running in a wide variety of environments can be found on my YouTube channel. To you as a developer, this means you write your application once, and users can run it in any kind of environment without you having to worry about it. If new input or output hardware comes along, it’s Vrui’s responsibility to support it, not yours.

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Vrui on (in?) Oculus Rift

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I wrote about my first impressions of the Oculus Rift developer kit back in April, and since then I’ve been working (on and off) on getting it fully and natively supported in Vrui (see Figure 1 for proof that it works). Given that Vrui’s somewhat insane flexibility is a major point of pride for me, what was it that I actually had to create to support the Rift? Turns out, not all that much: a driver for the Rift’s built-in inertial tracking unit and a post-processing filter to correct for the Rift’s lens distortion were all it took (more on that later). So why did it take me this long? For one, I was mostly working on other things and only spent a few hours here and there, but more importantly, the Rift is not just a new head-mounted display (HMD), but a major shift in how HMDs are (or will be) used.

Figure 1: The trademark “double-barrel” Oculus Rift screenshot, this time generated by a Vrui application.

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On the road for VR: Augmented World Expo 2013

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I’ve just returned from the 2013 Augmented World Expo, where we showcased our Augmented Reality Sandbox. This marked the first time we took the sandbox on the road; we had only shown it publicly twice before, during UC Davis‘ annual open house in 2012 and 2013. The first obstacle popped up right from the get-go: the sandbox didn’t fit through the building doors! We had to remove the front door’s center column to get the sandbox out and into the van. And we needed a forklift to get it out of the van at the expo, but fortunately there were pros around.

Figure 1: Me, digging into the sandbox, with a few onlookers. Photo provided by Marshall Millett.

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The Kinect 2.0

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Details about the next version of Microsoft’s Kinect, to be bundled with the upcoming Xbox One, are slowly emerging. After an initial leak of preliminary specifications on February 20th, 2013, finally some official data are to be had. This article about the upcoming next Kinect-for-Windows mentions “Microsoft’s proprietary Time-of-Flight technology,” which is an entirely different method to sense depth than the current Kinect’s structured light approach. That’s kind of a big deal.

Figure 1: The Xbox One. The box on top, the one with the lens, is probably the Kinect2. They should have gone with a red, glowing lens.

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On the road for VR: zSpace developers conference

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I went to zCon 2013, the zSpace developers conference, held in the Computer History Museum in Mountain View yesterday and today. As I mentioned in my previous post about the zSpace holographic display, my interest in it is as an alternative to our current line of low-cost holographic displays, which require assembly and careful calibration by the end user before they can be used. The zSpace, on the other hand, is completely plug&play: its optical trackers (more on them below) are integrated into the display screen itself, so they can be calibrated at the factory and work out-of-the-box.

Figure 1: The zSpace holographic display and how it would really look like when seen from this point of view.

So I drove around the bay to get a close look at the zSpace, to determine its viability for my purpose. Bottom line, it will work (with some issues, more on that below). My primary concerns were threefold: head tracking precision and latency, stylus tracking precision and latency, and stereo quality (i.e., amount of crosstalk between the eyes).

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First impressions from the Oculus Rift dev kit

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My friend Serban got his Oculus Rift dev kit in the mail today, and he called me over to check it out. I will hold back a thorough evaluation until I get the Rift supported natively in my own VR software, so that I can run a direct head-to-head comparison with my other HMDs, and also my screen-based holographic display systems (the head-tracked 3D TVs, and of course the CAVE), using the same applications. Specifically, I will use the Quake ||| Arena viewer to test the level of “presence” provided by the Rift; as I mentioned in my previous post, there are some very specific physiological effects brought out by that old chestnut, and my other HMDs are severely lacking in that department, and I hope that the Rift will push it close to the level of the CAVE. But here are some early impressions.

Figure 1: What it would look like to unbox an Oculus VR dev kit, if one were to have such a thing.

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An off-topic post

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I promised I would keep off-topic posts to a minimum, but I have to make an exception for this. I just found out that Roger Ebert died today, at age 70, after a long battle with cancer. This is very sad, and a great loss. There are three primary reasons why I have always stayed aware of Mr. Ebert’s output: I love movies, video games, and 3D, and he had strong opinions on all three of those areas.

When hearing about a movie, my first step is always the Internet Movie Database, and the second step is a click-through to Mr. Ebert’s review. While I didn’t always agree with his opinions, his reviews were always very useful in forming an opinion; and anyway, after having listened to his full-length commentary track on Dark City — something that everybody with even a remote interest in movies or science fiction should check out — he could do no wrong in my book.

I do not want to weigh in on the “video games as art” discussion, because that’s neither here nor there.

However, I do want to address Mr. Ebert’s opinions on stereoscopic movies (I’m not going to say 3D movies!), because that’s close to my heart (and this blog… hey, we’re on topic again!). In a nutshell, he did not like them. At all. And the thing is, I don’t really think they work either. Where I strongly disagreed with him is the reason why they don’t work. For Mr. Ebert, 3D itself was a fundamentally flawed idea in principle. For me, the current implementation of stereoscopy as seen in most movies is deeply flawed (am I going to see “Jurassic Park 3D?” Hell no!). What I’m saying is, 3D can be great; it’s just not done right in most stereoscopic movies, and maybe properly applying it will require a change in the entire idea of what a movie is. I always felt that the end goal of 3D movies should not be to watch the proceedings on a stereoscopic screen from far away, but to be in the middle the action, as in viewing a theater performance by being on stage amidst the actors.

I had always hoped that Mr. Ebert would at some point see how 3D is supposed to be, and then nudge movie makers towards that ideal. Alas, it was not to be.

Behind the scenes: “Virtual Worlds Using Head-mounted Displays”

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“Virtual Worlds Using Head-mounted Displays” is the most complex video I’ve made so far, and I figured I should explain how it was done (maybe as a response to people who might say I “cheated”).

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The reality of head-mounted displays

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So it appears the Oculus Rift is really happening. A buddy of mine went in early on the kickstarter, and his will supposedly be in the mail some time this week. In a way the Oculus Rift, or, more precisely, the most recent foray of VR into the mainstream that it embodies, was the reason why I started this blog in the first place. I’m very much looking forward to it (more on that below), but I’m also somewhat worried that the huge level of pre-release excitement in the gaming world might turn into a backlash against VR in general. So I made a video laying out my opinions (see Figure 1, or the embedded video below).

Figure 1: Still from a video describing how head-mounted displays should be used to create convincing virtual worlds.

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