2017

Table Of Contents
Camera Settings
Before analysing the 3D motion, define your camera properties. The camera represents the device used to
acquire the sequence of images you are tracking. For each camera parameter, you can choose to let the auto
3D tracker calculate the value automatically, you can specify the value yourself, or you can set a
perspective
grid
(page 653) to estimate the focal length. This information can help the automatic 3D camera tracker
calculate better results.
NOTE You can set the camera properties before initial tracking, or after initial tracking when calibrating or refining
the track.
Camera Type box Select the type of camera motion in the tracking shot.
To:Select:
Track a clip shot with a free-moving camera.Free 3D Motion
Track a rotating clip shot with a camera on a tripod.Pan and Tilt
Automatically detect the camera type and track accordingly (default value).Auto Detect Motion
Focal Length box Select Auto to let the 3D tracker calculate the camera values automatically. Select Manual
to specify the values yourself. Select Perspective Based to use the perspective rectangle in the image to
automatically determine the focal length of the camera.
Length field Displays the focal length of the camera, in millimeters. Editable.
Range Error field Displays the error of the estimate for the focal length. This should be a small number
relative to the focal length. Non-editable.
Zoom button Enable to calculate the zoom value of the reconstructed camera for each frame.
Film Back box Select the film back size of the camera that shot the scene.
Height field Displays the height of the film back. Editable.
Film Back Units box Select the unit of measurement (inches or millimeters) for the film back height.
Film Ratio field Displays the film aspect ratio of the camera. Non-editable.
Lens Correction Settings
You can apply lens correction before or after your initial analysis. If you make any changes after analysis,
you'll need to update or refine the track. While not necessarily required, performing a lens correction may
give better tracking results.
658 | Chapter 15 Compositing in 3D Space with Action