My Week With Project Tango

A few weeks back I got into Google’s exclusive Project Tango developers program. I’ve had a Tango tablet for about a week and have been experimenting with the available apps and Unity3D SDK.

Project Tango uses Movidius’ Myriad 1 Vision Processor chip (or “VPU”), paired with a depth camera not too unlike the original Kinect for the XBOX 360. Except instead of being a giant hideous block, it’s small enough to stick in a phone or tablet.

I’m excited about Tango because it’s an important step in solving many of the problems I have with current Augmented Reality technology. What issues can Tango solve?

POSITIONAL TRACKING

First, the Tango tablet has the ability to determine the tablet’s pose. Sure, pretty much every mobile device out there can detect its precise orientation by fusing together compass and gyro information. But by using the Tango’s array of sensors, the Myriad 1 processor can detect position and translation. You can walk around with the tablet and it knows how far and where you’ve moved. This makes SLAM algorithms much easier to develop and more precise than strictly optical solutions.

Also, another problem with AR as it exists now is that there’s no way to know whether you or the image target moved. Rendering-wise, there’s no difference. But, this poses a problem with game physics. If you smash your head (while wearing AR glasses) into a virtual box, the box should go flying. If the box is thrown at you, it should bounce off your head–big distinction!

Pose and position tracking has the potential to factor out the user’s movement and determine the motion of both the observer and the objects that are being tracked. This can then be fed into a game engine’s physics system to get accurate physics interactions between the observer and virtual objects.

OCCLUDING VIRTUAL CHARACTERS WITH THE REAL WORLD

Anyway, that’s kind of an esoteric problem. The biggest issue with AR is most solutions can only overlay graphics on top of a scene. As you can see in my Ether Drift project, the characters appear on top of specially designed trading cards. However, wave your hand in front of the characters, and they will still draw on top of everything.

Ether Drift uses Vuforia to superimpose virtual characters on top of trading cards.

Ether Drift uses Vuforia to superimpose virtual characters on top of trading cards.

With Tango, it is possible to reconstruct the 3D geometry of your surroundings using point cloud data received from the depth camera. Matterport already has an impressive demo of this running on the Tango. It allows the user to scan an area with the tablet (very slowly) and it will build a textured mesh out of what it sees. When meshing is turned off the tablet can detect precisely where it is in the saved environment mesh.

This geometry can possibly be used in Unity3D as a mesh collider which is also rendered to the depth buffer of the scene’s camera while displaying the tablet camera’s video feed. This means superimposed augmented reality characters can accurately collide with the static environment, as well as be occluded by real world objects. Characters can now not only appear on top of your table, but behind it–obscured by a chair leg.

ENVIRONMENTAL LIGHTING

Finally, this solves the challenge of how to properly light AR objects. Most AR apps assume there’s a light source on the ceiling and place a directional light pointing down. With a mesh built from local point cloud data, you can generate a panoramic render of where the observer is standing in the real world. This image can be used as a cube map for Image-based lighting systems like Marmoset Skyshop. This produces accurate lighting on 3D objects which when combined with environmental occlusion makes this truly a next generation AR experience.

A QUICK TEST

The first thing I did with the Unity SDK is drop the Tango camera in a Camera Birds scene. One of the most common requests for Camera Birds was to be able to walk through the forest instead of just rotating in place. It took no programming at all for me to make this happen with Tango.

This technology still has a long way to go–it has to become faster and more precise. Luckily, Movidius has already produced the Myriad 2, which is reportedly 3-5X faster and 20X more power efficient than the chip currently in the Tango prototypes. Vision Processing technology is a supremely nerdy topic–after all it’s literally rocket science. But it has far reaching implications for wearable platforms.

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