Delivering Undistorted Imagery

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Delivering Undistorted Imagery

After determining the lens calibration, you will use the image preprocessor system to produce an undistorted version of the shot.

- Determine lens distortion via calibration, checklines, or solving with Calculate Distortion.

- Save then Save As to create a new version of the file. (recommended).

- Click “Lens Workflow” on the Summary or Solver(Lens) panel.

- In most cases, ensure that the "Use input's bit depth" checkbox is turned on: if the input is 16 bit or floating point, you will likely want the same bit depth on output. If you have specifically set the bit depths on the shot setup panel, turn this off. (If the bit depth changes, the RAM cache will flush and reload automatically.)

- Select the “Final output” option “Undistorted(1)” and hit OK. The script will zoom in slightly so that there are no uncovered black areas in the output image.

- (If needed) Click “Save Sequence” on the Summary panel or Output tab of the image preprocessor (which lets you change resolution if you need to). Write out a new version of the undistorted imagery.

- Save then Save As to create a new version of the file. (recommended).

- On the edit menu, select Shot/Change Shot Images.

- Select the “Switch to saved footage” option on the panel that pops up, hit OK.

- You will now be set up to work with the undistorted (fixed) footage. If you tracked and solved initially to determine the distortion (or without realizing it was there), the trackers and solve has been updated to compensate for the modified footage.

- You can export to downstream applications now; the export will reference the re-written undistorted footage.

- You can track, solve, add effects, etc, all using the final undistorted imagery.

Tip : You may be able to perform the image distortion in your compositing application, to avoid round-tripping the images through SynthEyes, if the exporter to your application has the necessary support, or if you use Lens Distortion maps or static or animated projection screens.

If you need to do something different, or want to do more of the step manually, here is what is happening behind the scenes.

Note : If animated distortion is present, the Lens Workflow is doing much more work to achieve the same ends.

The Lens Workflow script performs the following actions for you: transfers any calculated distortion from the lens panel to the image preprocessor, turns off the distortion calculation for future solves, changes the scale adjustment on the image prep Adjust tab to remove black pixels, selects Lanczos interpolation, updates the tracker locations (ie Apply to Trkers on the Output tab), adjusts the field of view, and adjusts the sensor (back plate) width (so focal length will be unchanged), and sets up resampling in the image preprocessor so the undistorted image has the same resolution as the original.

When you do the Change Shot Images with the “Switch to saved footage” option, SynthEyes resets the image preprocessor to do nothing: if the lens distortion and other corrections have already been applied to the modified images, you do not want to perform them a second time once you switch to the already-corrected images.

The "Clear related controls" setting on the Lens Workflow panel clears the lens distortion, scale, and lens preset on the Lens tab, and the Crop settings on the Cropping tab (both tabs on the image preprocessor).

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