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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Blast from the Past

Aside

I just stumbled upon an interview I did almost four years ago for Greg Borenstein’s book “Making Things See: 3D vision with Kinect, Processing, Arduino, and MakerBot.”

The relevant part of the book, starting on page 29, is available online via Google Books. It’s cringeworthy because I’m talking about basically the same things I’m talking about these days, but had a hard time as this was before the current VR renaissance. I probably failed entirely to get my main points across to an audience that had never experienced VR, and had never considered it anything but an old and busted thing from the ’90s.

Messing around with 3D video

We had a couple of visitors from Intel this morning, who wanted to see how we use the CAVE to visualize and analyze Big Datatm. But I also wanted to show them some aspects of our 3D video / remote collaboration / tele-presence work, and since I had just recently implemented a new multi-camera calibration procedure for depth cameras (more on that in a future post), and the alignment between the three Kinects in the IDAV VR lab’s capture space is now better than it has ever been (including my previous 3D Video Capture With Three Kinects video), I figured I’d try something I hadn”t done before, namely remotely interacting with myself (see Figure 1).

Figure 1: How to properly pat yourself on the back using time-delayed 3D video.

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3D Video Capture with Three Kinects

I just moved all my Kinects back to my lab after my foray into experimental mixed-reality theater a week ago, and just rebuilt my 3D video capture space / tele-presence site consisting of an Oculus Rift head-mounted display and three Kinects. Now that I have a new extrinsic calibration procedure to align multiple Kinects to each other (more on that soon), and managed to finally get a really nice alignment, I figured it was time to record a short video showing what multi-camera 3D video looks like using current-generation technology (no, I don’t have any Kinects Mark II yet). See Figure 1 for a still from the video, and the whole thing after the jump.

Figure 1: A still frame from the video, showing the user’s real-time “holographic” avatar from the outside, providing a literal kind of out-of-body experience to the user.

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VR Movies

There has been a lot of discussion about VR movies in the blogosphere and forosphere (just to pick two random examples), and even on Wired, recently, with the tenor being that VR movies will be the killer application for VR. There are even downloadable prototypes and start-up companies.

But will VR movies actually ever work?

This is a tricky question, and we have to be precise. So let’s first define some terms.

When talking about “VR movies,” people are generally referring to live-action movies, i.e., the kind that is captured with physical cameras and shows real people (well, actors, anyway) and environments. But for the sake of this discussion, live-action and pre-rendered computer-generated movies are identical.

We’ll also have to define what we mean by “work.” There are several things that people might expect from “VR movies,” but not everybody might expect the same things. The first big component, probably expected by all, is panoramic view, meaning that a VR movie does not only show a small section of the viewer’s field of view, but the entire sphere surrounding the viewer — primarily so that viewers wearing a head-mounted display can freely look around. Most people refer to this as “360° movies,” but since we’re all thinking 3D now instead of 2D, let’s use the proper 3D term and call them “4π sr movies” (sr: steradian), or “full solid angle movies” if that’s easier.

The second component, at least as important, is “3D,” which is of course a very fuzzy term itself. What “normal” people mean by 3D is that there is some depth to the movie, in other words, that different objects in the movie appear at different distances from the viewer, just like in reality. And here is where expectations will vary widely. Today’s “3D” movies (let’s call them “stereo movies” to be precise) treat depth as an independent dimension from width and height, due to the realities of stereo filming and projection. To present filmed objects at true depth and with undistorted proportions, every single viewer would have to have the same interpupillary distance, all movie screens would have to be the exact same size, and all viewers would have to sit in the same position relative the the screen. This previous post and video talks in great detail about what happens when that’s not the case (it is about head-mounted displays, but the principle and effects are the same). As a result, most viewers today would probably not complain about the depth in a VR movie being off and objects being distorted, but — and it’s a big but — as VR becomes mainstream, and more people experience proper VR, where objects are at 1:1 scale and undistorted, expectations will rise. Let me posit that in the long term, audiences will not accept VR movies with distorted depth.

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2D Desktop Embedding via VNC

There have been several discussions on the Oculus subreddit recently about how to integrate 2D desktops or 2D applications with 3D VR environments; for example, how to check your Facebook status while playing a game in the Oculus Rift without having to take off the headset.

This is just one aspect of the larger issue of integrating 2D and 3D applications, and it reminded me that it was about time to revive the old VR VNC client that Ed Puckett, an external contractor, had developed for the CAVE a long time ago. There have been several important changes in Vrui since the VNC client was written, especially in how Vrui handles text input, which means that a completely rewritten client could use the new Vrui APIs instead of having to implement everything ad-hoc.

Here is a video showing the new VNC client in action, embedded into LiDAR Viewer and displayed in a desktop VR environment using an Oculus Rift HMD, mouse and keyboard, and a Razer Hydra 6-DOF input device:

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Installing and running first Vrui applications

In my detailed how-to guide on installing and configuring Vrui for Oculus Rift and Razer Hydra, I did not talk about installing any actual applications (because I hadn’t released Vrui-3.0-compatible packages yet). Those are out now, so here we go.

Kinect

If you happen to own a Kinect for Xbox (Kinect for Windows won’t work), you might want to install the Kinect 3D Video package early on. It can capture 3D (holographic, not stereoscopic) video from one or more Kinects, and either play it back as freely-manipulable virtual holograms, or it can, after calibration, produce in-system overlays of the real world (or both). If you already have Vrui up and running, installation is trivial.

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On the road for VR: Augmented World Expo 2013

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 Davisannual 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

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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