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Concave Dragons

The hollow face illusion in VR

Michael Abrash has now given two very public presentations on VR that have focused on covering the brain's ability to process input and how misinterpretations happen along the way. If you've not yet seen these talks, I strongly urge you to give them a look.

Time well spent.

Facebook's F8 Conference (March 2015):

Oculus Connect (September 2014):

One of the examples he recently gave as at F8 was a hollow face illusion based off of a pretty well known paper dragon cutout. If you take a look around the web, you'll find a number of different papercraft examples to let you print out and make your own. Well worth the 20 minutes or so it takes.

Inspired, I wanted to see if this illusion translated into VR.

Detailed Scientific Answer: Yep.

Four takeaways:

  1. VR strongly supports the exact same visual illusions that trick us in the real world. So, it is well worth studying these types of phenomena and seeing where they might be leveraged in VR.
  2. The effect is quite strong even in the absence of facial features (see last few moments of thevideo)
  3. VR makes for the perfect place to experiment with these kinds of visual tricks. While working with paper models requires a bunch of fiddly scissor, tab, fold, refold, mountain fold, VALLEY FOLD, work you can duplicate and alter VR models in a few moments to try out different effects and theories. Using this environment as a test bed, I imagine we are going to see a real a bunch of great new tricks and illusions whipped up over the next few years, discovered and refined in VR- then reproduced in the real world to devastating effect.
  4. If you are working on a model, aligning edges and the model that you are working on deliberately plays with your ability to perceive concave / convex shapes, you will feel like you are losing your mind.


I've had a number of requests for the source files for this project. You can grab them here: Unity 5 Scene.

Give me a shout at @ID_R_McGregor on twitter, or send me an email at id.r.mcgregor@gmail.com.

- by Robert McGregor, March 2015