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  • Wed 28 Apr 2010

    Does stereoscopy (S3D) matter ?

    Published at 12:42   Category Virtual Reality  

    Now everyone is starting to realize that stereoscopy (S3D) is cool. Of course big companies are hoping to set a new trend to get more of our money, and the film industry looks at it as if it was the new messiah.

    And of course I’m really happy to see this trend rising, this helps me explain my job to my family (“See Avatar? I’m doing that but you can also interact.”).

    What’s even more cool is that you can now play S3D games. That’s really interesting, but for me it’s only the first step towards real VR games, and maybe not even a necessary one! We’re not there yet, even with Natal, the PS3 Move or the Wiimote, but we’re on the Starway to VR heaven (c).

    But what is really stereoscopy useful for ?

    “To perceive depth, dumbass!”

    Yeah true, but a one-eyed person can still perceive depth, so stereoscopy is not the only cue to achieve this. And in reality, stereoscopy is not always the best cue; for example it is only relevant for distances up to a few meters.


    - Motion parallax, shadows, occlusion, perspective … -

    Parallax, the apparent displacement of objects when you move, is another very important cue. Objects close to your eye move faster than objects that are far. And according to Laure Leroy’s PhD thesis (Mines ParisTech, “Interfaçage visuel stéréoscopique : diminution de la fatigue visuelle et caractérisation de la perception des formes“), motion parallax (with head tracking) is at least, if not more, important than stereoscopy ! (Thank you Alexis!)

    Monoscopic cues (perspective, atmospheric artifacts (fog), relative sizes, occlusion, parallax, shadows), and stereoscopic cues (eye accomodation and convergence angle, disparity between left and right images) are all very important depth cues. ( “Le traité de la réalité virtuelle” has a very good chapter on depth perception in its first volume, chapter 3.2.3 [3rd edition])

    (It’s interesting to note that monoscopic cues are learnt, it’s a cognitive activity, whereas stereoscopy is also a neurological activity.)

    Look at these videos, you perceive depth but your screen doesn’t show stereoscopy ! Parallax in action :

    YouTube Preview Image YouTube Preview Image YouTube Preview Image

    The most striking example I have is from my own experience. One day I made a demo in our Cave, where you seat inside a car. While quickly setuping the demo, I didn’t realize that stereoscopy wasn’t enabled. Motion parallax induced by headtracking only was enough to give me a very good sense of depth. Then the whole group of people from the demo tried the car interior and nobody told anything about stereoscopy being disabled. I guess they probably didn’t notice.

    Only after David asked me : “Did you realize stereoscopy was off?”. No, I hadn’t ! I then returned to the Cave to understand how I could get fooled. So I switched stereoscopy on and off continuously for 5 minutes. Of course when you know it you see the difference. The distances and objects size seem weird. But I felt very present anyway ! ( Last week I had my stereoscopic capabilities check and their perfect, so it’s not just my eyes!). The fact that is was a car interior, with all objects pretty close is also probably a major factor. We tried on outdoor scenes and the result was much less convincing.


    - Made in Sri Lanka with the Fuji Finepix Real 3D W1 and StereoPhoto maker -

    Also I think people are not yet used to see stereoscopy on a screen. One day at Laval Virtual a stereoscopic movie was shown every 15 mins and the whole first day the left and right eyes were reversed. Nobody noticed or dared to say a word.

    The same happens when you have somebody wear a HMD: they won’t know if stereoscopy is on or off. Only if you turn it on they will notice the difference.

    What does this all mean ? Stereoscopy can be expensive to get. If your application doesn’t require precise size or distance evaluation, you can try to just use head tracking without stereoscopy, it might be more than enough !

    If your application requires distance or size evaluation, stereoscopy is probably required. Also know that it’s very hard to evaluate an absolute depth, but stereoscopy is very useful to evaluate a very small difference of depth. When seeing an object from 1m, we can perceive a 1mm depth difference. At 10m, we can only perceive a 10cm difference !

    On a cinema or movie screen you cannot have head tracking for a lot of people so stereoscopy is a very good addition to perceive depth and improve immersion.

    For VR games I’d first go with head tracking, but of course if you can get both .. :)

    Fri 23 Apr 2010

    VR Geeks of Paris, unite !

    Published at 9:20   Category Virtual Reality  

    So you’re a VR Geek and you live in Paris ? You want to meet other geeks like you, enjoy geeky immersive discussions and invent the future ?

    Join our VR Geeks Paris group and see you soon around a beer!

    Fri 23 Apr 2010

    An introduction to 3D user interfaces

    Published at 8:46   Category VR Applications  

    Dr Joe LaViola, one of the authors of the 3D UI bible “3D User Interfaces, Theory and Practice” has just released an article in Gamasutra to teach the basics of 3D UI to the game designers/programmers crowd.

    If you haven’t read the book, shame on you, but you can now read this very nice introduction and get an accelerated 3D UI course!


    What is a 3D spatial interaction anyway? As starting point, we can say that a 3D user interface (3D spatial interaction) is a UI that involves human computer interaction where the user’s tasks are carried out in a 3D spatial context with 3D input devices or 2D input devices with direct mappings to 3D. In other words, 3D UIs involve input devices and interaction techniques for effectively controlling highly dynamic 3D computer-generated content, and there’s no exception when it comes to video games.

    There are essentially four basic 3D interaction tasks that are found in most complex 3D applications. Actually, there is a fifth task called symbolic input — the ability to enter alphanumeric characters in a 3D environment — but we will not discuss it here. Obviously, there are other tasks which are specific to an application domain, but these basic building blocks can often be combined to let users perform more complex tasks. These tasks include navigation, selection, manipulation, and system control.

    It’s a really interesting move. The gamers are already using a lot of 3DUI but the developpers probably don’t know much about the research in this field. Let’s do the same with VR !

    Fri 16 Apr 2010

    Pictures, pictures and pictures

    Published at 14:53   Category Perso  

    After leaving Virtools, I needed a small break to think about what I really wanted to do with my life. Travelling is a good way to take some distance (aha), so I’ve decided to take some time to see life through different eyes.

    See after the break for some pictures.

    Read more…

    Thu 15 Apr 2010

    Laval Virtual 2010 – Clarte VR4D – VR for Design

    Published at 15:02   Category VR Applications  

    Clarte, who already brought to you the R-Screen, Ergo Wide 3, Sitac 3D and a lot of other VR pure joy, are now offering a very interesting application to help design small life spaces : VR4D.

    YouTube Preview Image

    As you can see, they use an iPod touch for system control (menus, numerical inputs) (B.A.T. anyone ??) . They can manipulate objects and virtual humans very easily and efficiently. They created a sort of virtual compass that you can sometimes see on the ground (the yellow arrow) to position yourself in the right direction and position.

    But definitely the coolest thing is that you can create objects. I’ve tried the whole application and it’s really nice to stand in the middle of your creation.

    They admitted that the video WorldBuilder was an inspiration for this part of the project.

    I want to be like them !

    Thu 1 Apr 2010

    pCubee : A Perspective-Corrected Handheld Cubic Display

    Published at 0:26   Category VR Displays  

    Here’s a nice prototype of display by the University of British Columbia, pCubee :

    YouTube Preview Image

    It has no stereoscopic capability, but the parallax (movements of objects based on their depth) is enough for you to correctly perceive their 3d position.

    We use magnetic sensor technology to help simulate real-time physics and to render coherent perspective for the user.