Stereoscopy in Animation: Definition, Process & Challenges

Sight is undoubtedly the most powerful sense for the average person, and you can use its amazing properties to create incredible animation experiences! That’s what stereoscopy is all about. But have you ever wondered about the science behind it? Look no further than this blog post, where we uncover the techniques behind stereoscopy!

What’s Stereoscopy

Stereoscopy is a technique to create the illusion of three-dimensional depth by presenting slightly different images to each eye.

This is done with the use of specialized glasses or other viewing devices like VR headsets that allow each eye to see a slightly different image, creating the perception of depth and dimensionality.

Why Stereoscopy

Stereoscopy can be used in immersive 3D environments, but also in 2D animations. It adds 3D depth to animations, creating a more realistic result to give a sense of immersion.

It allows animators to tell stories in new and innovative ways by creating more complex and dynamic scenes with finer details. For example, stereoscopy greatly enhances camera movements: in battle scenes, stereoscopy gives the viewer a better sense of what’s going on.

Stereoscopy is here to stay: it has advanced significantly in recent years, with new technologies like VR and AR allowing for even more immersive experiences. As these technologies continue to evolve, animators will have even more opportunities to experiment with stereoscopy in their work.

Who Does Stereoscopy

A stereographer manages everything related to stereoscopy: the technology to best create 3D effects in the context, how it’s integrated in the animation project, and the adjustments throughout the project lifecycle. The role ensures the stereoscopic effects work as expected to enhance the viewer's experience.

Stereographers work closely with directors, cinematographers, and other members of the production team to plan and execute stereoscopic effects.

In the technical aspects of the production, stereographers oversee things like camera positioning, lens selection, alignment, and viewing devices. They work with specialized software and hardware to calibrate the final product for various stereoscopic devices.

How Does Stereoscopy Work

Stereoscopy creates the illusion of 3D using 2D images or videos, by presenting slightly different images to each eye that simulates the way our eyes naturally perceive depth in the real world. The left and right eye images are then displayed simultaneously with dedicated viewing devices to separate the images and send them to the correct eye.

While the principle looks simple, it involves a lot of work throughout the entire animation pipeline lifecycle:

Planning - During pre-production, the team decides whether the project will be created in 3D, and if so, whether it will be displayed in stereoscopic 3D or not. The choice depends on the allocated budget and the nature of the animation project―whether it adds to the experience or not. If stereoscopy is desired, the team will need to plan and design the project with this in mind. Avatar is a famous example of using stereoscopy to create a more vivid world.
Production - During production, the animation is created in 2D or 3D using specialized software. While making the scenes, the artists have to check the result looks good in stereoscopic 3D as well.
Stereoscopic conversion - Once the animation is complete, it’s converted into stereoscopic 3D: the technicians take the original 3D animation and create two slightly different images that will be used to create the illusion of depth.
Editing - The stereoscopic images are then edited to ensure they align properly. The editor also makes sure the animation looks good from all angles.
Delivery - Once the stereoscopic 3D animation is complete, it can be delivered to theaters or other venues for viewing. Special 3D glasses are typically required to view the animation in stereoscopic 3D.

Of course, the process needs to be adapted to the animation type (2D, 3D) and the intended release environments.

Common Stereoscopy Techniques

There are various techniques to capture or create the two images used in stereoscopy, depending on the display technology being used, and the budget and resources available for the project:

Side-by-side - Two separate images are placed next to each other on a single frame or screen, with the left image on the left side and the right image on the right side. This is commonly used in 3D movies.
Anaglyph - The oldest and most widely used technique for creating stereoscopic 3D images. It involves using two offset images (typically one red and one cyan) to create the illusion of depth. Viewers wear red-cyan glasses to view the image.
Polarized - Two images are projected on the screen simultaneously, each with a different polarization―the direction of a lightwave in space. Viewers wear polarized glasses that match the polarization of the corresponding image, allowing the brain to combine the images and create the illusion of depth.
Active - Using specialized glasses that rapidly alternate the left and right lenses, synchronized with the alternating display of the left and right images on the screen. Though it requires specialized equipment, it can produce brighter and clearer 3D images.
Autostereoscopy - A screen layer allows different images to be viewed from different angles. This eliminates the need for glasses, but the technology is still in development and is not yet widely used.
Interlaced - This technique alternates rows of pixels in the left and right images, using specialized software to decode the images and create the illusion of depth.
Frame Sequential - Involves alternating between left and right frames at a high frame rate (typically 120Hz or higher), with specialized glasses that rapidly alternate between left and right lenses to create the illusion of depth.

Best practices For Stereoscopy

Stereoscopic errors can significantly delay production schedules and box-office success, so it’s important to get the process right by following some best practices:

Plan for stereoscopy from the beginning - Stereoscopy affects every aspect of the animation process, from character design to camera placement: it can’t be an afterthought, and it's important to plan for stereoscopy from the very beginning to ensure that all elements of the animation are optimized for 3D viewing.
Use consistent interaxial distance - The interaxial distance is the distance between the cameras that capture the left and right eye images. Using a consistent interaxial distance is important for creating a comfortable viewing experience. A distance of 2.5% to 3% of the screen width is generally recommended.
Avoid excessive depth - While depth is important for creating a realistic 3D effect, it's important to avoid excessive depth that can cause eye strain or discomfort. Keep the depth within the natural range of human vision.
Use depth cues - Depth cues such as atmospheric perspective, overlapping objects, and shadows can help enhance the 3D effect and make the animation more immersive. These details require additional planning and work, but they really make or break a production.
Test in different viewing conditions - It's important to test the stereoscopic animation in different viewing conditions―: on different sized screens, in different lighting conditions, and with different types of glasses to ensure that the animation always looks good.
Use motion carefully - This has been documented countless times with the use of VR headsets: motion can be challenging in stereoscopic animation, as it can cause discomfort or nausea in some viewers, so use motion carefully and avoid rapid movements or excessive parallax.

Because stereoscopy involves collaborating with many art departments, it’s important to have processes and tools in place to work effectively with teammates, like Kitsu. Kitsu is a production pipeline tracker used by hundreds of animation studios around the globe to regularly gather feedback, create new revisions, set the right priorities for your tasks, and have a central place to share and store stereoscopic assets.

Conclusion

Stereoscopy is becoming more and more prominent with applications ranging from Metaverse animations to film production. Understanding the process and techniques involved is important to fully leverage this technology in your animation studio.

If you are a stereographer, an aspiring artist, or someone who simply enjoys learning about the animation industry, we invite you to join our Discord community. Here, you can connect with fellow artists, share your work, and learn from others in the industry.