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Electronic Calibration
To electronically calibrate, print out the calibration grid from the web site using a large-format black and white (drafting) printer, which can be done at printing shops such
as Fedex Kinkos. Attach the grid to a convenient wall, perhaps with something like Joe’s Sticky Stuff from Cinetools. Position the rig on a tripod in front of the wall, as close as it can get with the entire outer frame visible in both cameras (zoom lenses wide open).
Adjust the height of the rig so that the nodal point of the cameras is at the same height as the center point of the grid.
Re-aim the cameras as necessary to center them on the grid. This will converge them at that distance to the wall; you may want to offset them slightly outwards or inwards to achieve a different convergence distance, depending on what you want.
Shoot a little footage of this static setup. Record the distance from the cameras to the wall, and the width of the visible grid pattern (48” on our standard grid at 100% size).
For camcorders with zoom lenses, you should shoot a sequence, zooming in a bit at a time in each camera. You can use one remote control to control both cameras simultaneously. This sequence will allow the optic center of the lens to be determined— camcorder lenses are often far off-center.
Once you open the shots in SynthEyes, create a full-width checkline and use the Camera Field of View Calculator script to determine the overall field of view. Use the Adjust tools on the image preprocessor to adjust each shot to have the same size and rotation angle. Use the lens distortion controls to remove any distortion. Correct any mirroring with this pass as well, see the mirror settings on the image preprocessor’s Rez tab. Use the Cropping and re-sampling controls to remove lens off-centering. A small Delta Zoom value will equalize the zoom. See the tutorial for an overview of this process.
Your objective is to produce a set of settings that take the two different images and make them look exactly the same, as if your camera rig was perfect. Once you’ve done that, you can record all of the relevant settings (see the Export/Stereo/Export Stereo Settings script), and re-use them on each of your shots (see Import/Stereo/Import Stereo Settings) to make the actual images match up properly. Then, you should save a modified version of each sequence out to disk for subsequent tracking, compositing, and delivery to the audience.
Obviously this process requires that your stereo rig stay rigid from shot to shot (or periodic calibrations performed). The better the shots match, the less image quality and field of view will be lost in making the shots match.
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