Anamorphic 6th-order Controls

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‌Anamorphic 6 th-order Controls

This is the usual lens type for handling anamorphic shots, either in the compositing-friendly standard (Std.) version, or the matchmoving-friendly version. The “ Anamorphic, Merged” variant presents fewer parameters, and is better for simpler, less data-rich situations, such as largely-static lens breathing shots with little camera motion.

Note: Anamorphic solving is not available in SynthEyes Intro.

The images above show two of the three panels for the anamorphic lens types; the Y’s panel is the same as the X’s panel, but for Y coefficients. Note that in the Merged lens types, there is only a C’s panel that controls identical values for both X’s and Y’s. Our discussion here will thus cover all four variants: compositing-friendly and matchmoving-friendly versions of normal or merged versions of the underlying anamorphic model.

On the main coefficient panels (X’s, Y’s, or C’s), here’s what the coefficients are:

C*02. Main radially-symmetric quadratic distortion coefficient.

C*04. Main radially-symmetric quartic distortion coefficient.

C*06. Main radially-symmetric sextic (6 th order) distortion coefficient.

C*22. Asymmetric second-order distortion coefficient.

C*24, C*44. Asymmetric fourth-order distortion coefficients.

C*26, C*46, C*66. Asymmetric sixth-order distortion coefficients.

Note that the asymmetric coefficients don’t have any particularly useful physical interpretation; these are computed as part of the solve (when enabled).

HSCL is a horizontal image scaling adjustment that can be used to handle lens focus breathing, instead of selecting a zoom lens. Since Uscl is equivalent to a zoom,if you use Uscl, you must have already determined the (static) field of view, and changed to Known FOV lens mode (answer yes to copy solved FOV to seed FOV). HSCL should always be solved using one of the two animated solving modes.

VSCL is similarly used to scale the image vertically to handle focus breathing. It is not redundant to field of view, so you can solve for it while using a fixed or zooming lens, no need to switch to Known. For lens breathing it must be solved as animated; in rare cases where you’re very unsure of the image aspect ratio you might solve for it as static, but that is possible only if the image has significant rotation around the optic axis.

ROT is the orientation error of the anamorphic lens as mounted to the camera, ie the degree to which the anamorphic axes don’t align with the sensor’s axes. This can and should only be determined if there is a significant difference in horizontal vs vertical distortion or scaling. Solving for the value when there’s no difference will destabilize the solve, and a non-zero value can complicate downstream compositing, so you should experiment with this parameter only after getting a reasonable solve to start with.

Anam.Dist. is the anamorphic distance—the distance between the horizontal and vertical entrance pupil positions in SynthEyes scene coordinates ( not mm or inches). This is not a lens distortion coefficient. In the graph editor, it appears directly under the camera, not in the Lens Distortion subsection. It is a fundamental modification to the 3-D to 2-D perspective transform peculiar to anamorphic lenses; it is behind anamorphic oddities such as different horizontal and vertical focus sharpness, anamorphic mumps, and the different horizontal and vertical scaling during focus breathing. Non-zero values are not necessarily handled in 100% of all SynthEyes algorithms, and will complicate operations in downstream applications. However, it may be your only way to get accurate matches on some anamorphic shots. See the Anamorphic Shots Guide for more details. This track is automatically cleared if you switch to a non-anamorphic lens type, to prevent havoc.

HCTR, VCTR, and Rolling Shutter are discussed in the Shared Parameters section.

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