< Previous | Contents | Manuals Home | Boris FX | Next >
Lens Distortion Profiles
Dated material: More complete information, including the full results of the Lens Workflow process, can be stored as scripts, instead of .lni files. Use “File/Export/Lens/Image preprocessor preset as script” to produce the script, then use Script/Run script to load the preset into additional shots.
SynthEyes can use stored information about known, pre-calibrated, lenses from special files with the file extension “.lni” (lens information), or from "image map" files that look like colorful gradients. These can be stored in the Lens sub-folder of the scripts folder, for frequently used profiles such as for a camera you own. There are two preset folders, a system set and a user-specific set. Lens presets can also be read directly from a specified preset file anywhere in the file system, for example located with the image files for project-specific profiles.
Note : Having many lens distortion presets will increase SynthEyes's startup time. One-time-use distortion files and maps should be stored with the source imagery, rather than cluttering up the presets.
The .lni lens information files contain a table of values mapping from the “correct” radius of any image point to the distorted radius. These tables can be generated by small scripts, including a default fish-eye lens generator (which has already been run to produce the two default fisheye lens files), and a polynomial generator, which accepts coefficients from Zeiss for their Ultra-Prime lens series.
These distortion maps can be either relative, where the distortion is independent of the physical image size, or absolute, where the distortion is described in terms of millimeters. The relative files are more useful for camcorders with built-in lenses, the absolute files more useful for cameras with removable prime lenses.
The absolute files require an accurate sensor (back plate) width in order to use the table at all. Do not expect the lens calibration table to supply the value, because the lens (ie a detachable prime lens) can be used with many different cameras!
For assembled camcorders, typically with relative files, the lens file can supply optional nominal sensor (back plate) width and field of view values, displayed immediately below the lens selection drop-down on the image preprocessor’s lens tab. You can apply those values as you see fit.
When you select or open a preset, some additional information about the setup may be loaded into the image preprocessor as well, especially the required padding values.
If you change an lni file (by re-writing it with a script, for example), you should hit the Reload button on the Lens tab, while that lens file is selected. If you add new files, or update several, use “Find New Scripts” on the main File menu.
©2024 Boris FX, Inc. — UNOFFICIAL — Converted from original PDF.