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Notes
This script is a experiment demonstrating the effect of rolling shutter, and why it is problematic, not a way to remove it in general.
The shot MUST BE SOLVED before running the script, or it won't do anything useful. It compensates for the distortion of the background (only) as the camera moves.
Plausibly self-consistent only for tripod-type shots.
Note that the mesh distorts vertically as well as horizontally, even rotationally. Rolling shutter distortion occurs for ANY direction or amount of motion (ie not just pan)!
Rolling shutter compensation is possible only for relatively low-frequency motions. Higher-frequency vibrations inherently can't be compensated; they result in the dreaded jello shot.
Use Average Scene Distance for rough compensation for non-tripod shots. For translating shots, the required compensation is different for every pixel, based on the distance from the camera. Since we don't have that, and even if we did there are problems with occlusion, the compensation is necessarily approximate at best, suitably only for simple and smooth camera motions vs a relatively flat background.
Independently-moving objects (people, cars) require different compensation that the script does not address; the compensation here is for stationary background.
Accommodates any kind of lens distortion that the image preprocessor does, included animated and anamorphic.
Accommodates zooming cameras, though they make it more difficult to reduce the field of view.
Note that the rolling shutter effect must be determined based on the vertical position within the original camera image, BEFORE any lens distortion correction. You should run the script only with the image preprocessor set up to do the undistortion, NOT after you've rendered undistorted footage and reset the image preprocessor.
The overall process is for a Lens Workflow #1; there's no reverse "redistort" path.
©2024 Boris FX, Inc. — UNOFFICIAL — Converted from original PDF.