Calibration

Lens calibration involves determining and applying the parameters that define how a lens refracts light and projects an image onto a camera sensor.

This process is indispensable for integrating computer-generated imagery (CGI) with live-action footage, ensuring that CGI elements align accurately with the physical environment captured by the camera.

It requires adjusting the virtual camera settings to match the real camera's characteristics, such as focal length, aperture, and distortion.

When executed correctly, lens calibration results in a seamless blend of digital and real elements, creating a believable and immersive final image or scene. Without proper calibration, CGI and live-action elements can appear disjointed.

Key Terms in Lens Calibration:

• Focal Length / Field of View (FoV): Defines how wide the lens captures the scene.
• k1 and k2: Parameters that measure lens distortion at the edges of the image compared to the center.
• Center Shift: The offset between the lens center and the camera sensor center, which can vary when the lens is mounted or zoomed.
• Nodal Offset: This is the distance between the lens's front nodal point and its rear nodal point. It's a fixed property of the lens design itself and does not change when you focus the lens.
• Focus Distance: The distance from the camera sensor to the point of focus. In other words, it describes how far the lens is from the camera's sensor.