Chapter 45: 360˚ visual effects
Excerpt from Chapter 45: 360˚ visual effects, page 212:
...Your editing software likely comes with dozens of special effects to modify the appearance of your videos. Some of these effects can be used on a 360˚ clip, but many cannot. Any effect that modifies the edge of the frame, or uses the edge to hide changes it makes to the image, won’t work in a 360˚ shot, which has no edges. The “edge” of a latlong image wraps around to the other side when the video is played in a headset.
Latlong (latitudinal-longitudinal): Stretching a spherical image into a flat rectangle (similar to the way a world map represents the spherical Earth). Also called equirectangular.
Effects like blur (used for removing noise) and sharpen (used for improving soft focus) work by spreading the pixels out in certain areas of the image. In ordinary video, some modified pixels may get pushed off the edge of the frame, but in 360˚ video any pixel pushed off the left edge of the frame must appear on the right edge, and so forth.
If you apply an ordinary filter to 360˚ video, you’ll wind up with a visible line down the back of your sphere where these pixels got shifted.
If instead you use a special filter designed for use with 360˚ video, you’ll get the blurring or sharpening effect you desire, but without spawning that distracting line.
Both Mettle and Dashwood Cinema Solutions provide specific plug-ins for performing these kinds of effects...