Introduction

A huge thanks to the brilliant team at Matchmove Machine for sharing this workflow on lens distortion.

Matchmove machine is a team of technical experts in 3D tracking and matchmoving. Matchmove Machine provide 3D tracking services for Feature Films, Music Videos, Commercials, TV Shows and are ready to be with you at all stages of production to ensure a truly impressive and high-quality result, while remaining invisible to the viewer.

Workflow

For the proper integration of CG elements into live footage, it’s important to account for camera distortion.

The workflow for handling lens distortion is as follows:

1. Start with the original footage (plate).
2. Remove the lens distortion (undistort the plate).
3. Perform camera tracking and matchmove on the undistorted plate.
4. The CG pipeline works with the undistorted material.
5. The CG object is rendered on an alpha channel with added overscan to prevent tiling after distortion is reapplied. Overscan ≠ Render resolution
6. The lens distortion is reapplied to the CG render.
7. The final render is composited with the original footage.

Remember, if you don’t apply overscan, the edges of the image may be cropped or stretched by tiling once the distortion is reapplied.