Unpackaging: 360˚ Video and Real-time CG Elements Compositing in Unity

At Unity Vision Summit a couple days ago, Unity announced that 360˚ video compositing will be available in “Unity2017”. Unity2017 is the next stable release of their engine, said to focus on artists and designers.

With this new feature in Unity engine, anyone can add graphics effects such as lens flares, digital animations, and interactivity in real-time to a video. The presenter Natalie Grant, a Senior Product Marketing Manager @Unity of VR/AR/Film, said one of the most important aspects about VR is that it achieves the “feeling like you are actually there.” She continued, “These are a few small ways to make a regular 360˚ video interactive and immersive”.

The purpose of this post is to explain that I posit that consumers and creators alike will learn more about computer graphics topics like (General Purpose GPU usage) and virtualization of the real-world. WebVR and 360˚ content on laptops and phones will “bring people up the immersion curve” as Mike Schroepfer says. This approach where content is composed of 360˚ video and real-time 3D model content will contribute to that.

 

What is compositing?

Compositing is combining of visual elements from separate sources into single images.

How it’s achieved in Unity with 360˚ videos

As described in the talk*, 360˚ composited with real-time CG elements is essentially two spheres in a scene and 360˚ videos on the interior of each sphere with a camera at the shared center point. To explain, imagine the layers of the Earth as an analogy.

earth_analog

The inner core is essentially the user’s head or main camera looking around the environment. The outer core is the first 360˚ video player with a shader** applied to it masking some of the video but not all of it. Skipping the lower mantle temporarily, the upper mantle is where the second 360˚ video player is. This upper mantle is showing the same 360˚ video as the inner player but normally, without a shader. In between, the lower mantle is where users can now place digital animations, 3D objects, and UI elements that are interactable. This is where all the magic happens–specifically because the space between the two concentric 360˚ video player spheres allows for CG content to really seem in the scene. Both copies of the composited 360˚ video are exactly in alignment–meaning that as long as the user’s view position is confined to 3DoF, the user can’t tell there are two copies of this video file playing when viewing this.

Finally, for more immersion, the Crust and the rest of Space, is also a layer where any Unity object can be positioned.

Natalie shows this is important in the use case of matching a Unity directional light source to the position, direction, and intensity of the sun as captured in a 360˚ video. This means that because of Unity’s physics based rendering, the CG elements (in the lower mantle or outer crust with standard shaders) should have shadows, color, reflections and more produced in a realistic way (because they are affected by the light source). This increases the effectiveness of the illusion that footage and real-time elements are composited.

Another way to think about this approach is as the Russian nesting dolls of spheres (credit: Ann Greenberg). In this comparison, each doll corresponds to a 360˚ video sphere, and just like the dolls, the spheres are concentrically nested and aligned with the same rotation.

russiandolls

As demonstrated by Natalie on stage, when done deliberately enough the 3D content will actually look like it’s in the camera-captured shot. Creating the illusion that 3D objects are occluded or hidden behind the inner sphere playing video (see below a 3D dinosaur moving behind the first 360 video).

ujyxCC.gif

In the short-term, I think this will help people engage with more 360˚ video content and potentially excite people about mixing camera captures and virtual content.

 

When demonstrating “locomotion in 360˚ video”, Natalie Grant of Unity showed that one can click to move to another 360˚ video. For starters, this isn’t exactly like movement with teleportation in a completely digital environment, where one can teleport anywhere a pointer collides with a plane. Remember that the creative behind the project must capture each 360˚ video using a camera and tripod, and that’s still a constraint on the freedom of choice for location. However, with potentially a lot less work, the creative can begin making compelling 360˚ video experiences with an interactive component (i.e. switching the 360˚ video) and layers of spatially accurate CG objects.

Also at this year’s F8 developer conference Facebook announced a new camera, the Surround 360 video camera, that will let users move around inside live-action scenes. The product can infer 3D point and vector data of its surroundings using overlapping video image data from adjacent cameras. So a reasonable implication is that we may even have 6 DoF live action scenes eventually with CG elements composited***.

However, I’d imagine that blind spots would exist once a user has moved significantly from the original center of the two spheres, and that will also impact the integrity of the illusion that both CG and video are composited.

 

I look forward to seeing some creative applications of this method.

*found at the 35-minute mark https://www.youtube.com/watch?v=ODXMhaNIF5E

** A Unity Standard Shader attempts to light objects in a “physically-accurate” way. This technique is called Physically-Based Rendering or PBR for short. Instead of defining how an object looks in one lighting environment, one needs only to specify the properties of the object (e.g. how metal or plastic it is).

Then, the shader computes its shading based on those factors.

***The original Surround 360 was estimated to cost about $30,000 at using the company’s exact schematics.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s