This is the first of our 360˚ Video Top Tips series. The aim of this series is to provide useful tips that 360˚ video and immersive content creators can apply to future productions. In this series we talk about capture and synchronisation for beginners, post-production and optical flow stitching at an intermediate level and stereoscopic capture for more advanced creators.
If you’re using a multi-camera 360˚ system - make sure your video signals are genlocked.
You’re probably all aware of the most commonly publicised methods which are used to synchronise camera arrays in post-production - a slate, remote, or flash won’t be effective if your cameras do not start capturing frames at the same time.
Regardless of how technically complicated your post-production pipeline is, a half frame synchronisation issue will always be evident in the final production as slight but constant movement between plates/individual cameras, especially if the 360˚ video features movement and/or vibration.
More info on improving your synchronisation skills with 360˚ video.
Block subjects and stage actions during production to minimise potential artefacts caused by stitching.
Almost all camera and stitch combinations and algorithms will unintentionally cause artefacts and imperfections during the stitch process, however, understanding the common causes of artefacts for your camera and stitch workflow/s will allow you to apply best practices to your shoot.
An example of this includes ensuring subjects are of a sufficient distance from the camera for the algorithm to be able to clearly distinguish clear variations in pixels during an ‘optical flow’ stitch.
If an object or subject is too close to the camera, the surrounding vision of the scene could be obscured in the adjacent camera/s and therefore affect the algorithm's ability to accurately see around the object. The algorithm must then compensate by estimating and generating pixels which do not exist, this can then result in a potential miscalculation and imperfection in the stitch. If there are too many similar pixel formations, the optical flow algorithm can experience difficulty determining which point to match between the similar points. The solution to this is to ensure that the primary action is staged in a safe zone.
More info on improving your post-production technique with 360˚ video.
Block and capture subjects and action within the correct ‘stereo window’ if you’re using fixed interaxial distance (single or multiple unit) stereoscopic camera/s to capture 360˚.
You’ll often be limited by a fixed rig, the purpose of which is to ensure a complete 360˚ spherical wrap is achieved whilst also capturing in stereoscopic 3D. This limits the control you have of the ‘stereo window’, therefore it’s recommended that equations such the 1/30th rule are used to calculate the correct ‘stereo window’ for a fixed 360˚ stereoscopic camera setup.
The average distance between the eyes of humans - also known as the interocular - is considered to be about 2.5”. It is recommended that the interaxial distance between a stereoscopic camera setup should be as close to the human interocular distance as possible to achieve ‘ortho-stereo’. Interaxial distances closer than 2.5” result in ‘hypo stereo’ which makes objects appear larger than they actually are. Interaxial distances greater than 2.5” result in ‘hyper-stereo’ which makes objects appear smaller than they actually are with exaggerated separation between objects, also know as a depth effect.
More info on improving stereoscopic capture with 360˚ video.