Hands-On with Birdly, a Virtual Reality Flight Simulator

By Norman Chan

One of the most immersive virtual reality demos I've used uses a novel control scheme to simulate something that most people have never actually experienced before: the act of flying. And the sensation is incredible.

"Since the days of Copernicus, man has dreamed of flight. On this historic day, we remember the Wright brothers, Orville and Redenbacher. Whose dreams and visions inspired generations. And now, again, one man's vision ushers in a new era of aerial travel. Proving the power of Imagination, and Intellect. The magic... of Flight." - Eric Cartman

One of the hurdles that this current wave of virtual reality has to overcome is finding control mechanisms for virtual spaces. Whether that means gamepads, prop weapons for shooting games, accessories like steering wheels and flight sticks, or full-on hand and arm tracking, these systems will have be appropriate and intuitive enough to match the software you're seeing through a head-mounted display. If you're playing a racing game from the perspective of a driver behind the steering wheel, you want the control system to match what your brain knows about steering and driving from real-world experiences. But interestingly enough, one of the most immersive virtual reality demos I've used uses a novel control scheme to simulate something that most people have never actually experienced before: the act of flying. And the sensation is incredible.

Birdly is a research project being conducted at the Zurich University of the Arts. Lecturer Max Rheiner and a small team of students began experimenting with a virtual reality rig last November, culminating in the the Birdly system that Max and his team are now taking on tour. We visited Max at the swissnex offices in downtown San Francisco last week to try out Birdly before it went to the Exploratorium and then onto this week's SIGGRAPH conference.

Rheiner told me that the goal of Birdly was simple: to embody the experience of flying like a bird though a full-motion simulator. But getting to that goal with a motion-control rig built from scratch, and then tuning the experience to match what users intuitively understand as a bird's flight was a bit of a challenge. Over six months, Max's team fabricated and tested several prototype rigs (documented in videos here) before coming up with the Birdly system we used. And surprisingly, the current setup looks very polished--more like a beautifully crafted modern furniture than homemade exercise machine. The rig looks like a futuristic massage table, with users lying flat on their belly atop the padded frame. Users put on an Oculus HMD (the first development kit) along with headphones, before stretching their arms out on what are essentially wings. A fan is mounted on the front of the rig simulates wind being blown in the user's face.

After mounting on the table and strapping all the VR gear, the software booted up and dropped me in a virtual model of San Francisco, placing me a mile above where my body actually was in downtown SF. Birdly uses ariel imagery and building models provided by mapping companies--Pictometry International and PLW Modelworks--and the city looked as like a high-resolution version of Google Earth. Then I started flapping for dear life.

As a VR demo, the simulation completely immersed me in the experience of flying, or what my mind believed flying like a bird would be like. It was almost dream-like. Immersion is achieved through the combination of low-latency head-tracking, full-motion feedback (the bed actually tilts on several axes), and the intuitiveness of the flapping control mechanism. I had to actually flap my arms to stay afloat, and the bed provided enough resistance to make me believe that I was flighting the wind. The "wings" have two primary axes of movement--flapping up and down at the shoulders and rotation at the forearm. Those axes allowed me to pivot to turn and change my flapping speed from a forward glide to an upward lift.

With just a minute of getting my bearings--and several near misses between skyscrapers--I was comfortably flapping my way around San Francisco airspace, playing the class "find your home and office" game and even diving down to city streets. The experience was euphoric and liberating, without any sense of motion sickness afterward. The wind feedback from the front-mounted fan also increased my sense of immersion, with stronger gusts matching increases in speed and altitude. I could've stayed in the demo for much longer than the five minutes allotted. Max told me that everyone who has so far tried it "gets it" almost immediately--a big sign of Birdly's success is its universal intuitiveness, even for users with no previous VR experience. The only caveat was that my arms and chest were a little sore the next day. (Birdly doubles as the fun workout!)

A reason Birdly succeeds is because Max and his team aren't building a consumer product. As a one-off research and art installation, it doesn't have to be designed with mass manufacturing in mind or budget constraints. That also means that the Birdly team can continue to improve on their rig, in both software and hardware. On the software side, the user feedback surfaced at demos informs the tweaking of the flight parameters. Birdly is being continually tuned to better simulate the flying experience. It may not be exactly how a bird flies, but that's OK. It just needs to match what humans intuitively think of as the experience of flight. And we've all had flying dreams.

Screenshot by Birdly

On the hardware side, the next steps are a little more clearcut. Max wants to upgrade the HMD to the Oculus Development Kit 2, as well as find a software pipeline for loading higher-resolution textures and model details onto the virtual environment (no easy feat when the current system already taps into 50GB of map data). The flapping mechanism will also get an overhaul to add an additional axis of movement for speed control: sweeping the wings back to accelerate into a dive. The team is also experimenting with haptic feedback on the bed itself to let users feel the sensation of landing. And one experimental system will provide olfactics to Birdly--the sense of smell. Max showed me a small add-on rig created in partnership with a fragrance designer to pump the scents of a city (think smoke, asphalt, and mist) to users.

It's clear that Max and his team are having a lot of fun exploring the possibilities of Birdly. They see potential uses in psychology research, therapy, and of course, gaming. In my mind, there's no reason Birdly can't expand beyond its original scope of simulating bird flight and be used in a spaceflight simulator. (Silverhawks!) But even in its current iteration, it's already one of the best examples of how virtual reality can grant users an out-of-body experience that not even the Wright brothers dreamed of.