User Manual

How to Manually Determine Lens Distortion
In an ideal world, one would have exact lens parameters from each lens that was used during
the shoot, and one could use those values to undistort the image. However, in the real world,
those parameters have not been taken on set or don’t match. Another approach is to use
software like 3D Equalizer, which analyzes the footage and delivers a dataset that can be
imported into the Lens Distort node right away.
And finally, one could try to manually eyeball the amount of lens distortion using the control
sliders. To do that, one could either look for horizontal or vertical lines in the footage that are
supposed to be straight and straighten them out using the controls, or shoot a full-frame
checkerboard pattern on set as a reference.
Common Controls
Settings Tab
The Settings tab in the Inspector is also duplicated in other Warp nodes. These common
controls are described in detail at the end of this chapter in “The Common Controls” section.
Perspective Positioner [PPN]
The Perspective Positioner node
Perspective Positioner Node Introduction
The Perspective Positioner is the complementary node to the Corner Positioner node. It
“unpins” an image by positioning corner points on a perspective distorted area, thereby
removing the perspective from the image. This function can also be used to wobble and warp
the image by animating the points over time.
Inputs
The two inputs on the Perspective Positioner node are used to connect a 2D image and an
effect mask, which can be used to limit the transformed area.
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Input: The orange input is used for the primary 2D image that is transformed.
–
Effect Mask: The blue input is for a mask shape created by polylines, basic primitive
shapes, paint strokes, or bitmaps from other tools. Connecting a mask to this input
limits the transform to only those pixels within the mask. An effects mask is applied
to the tool after the tool is processed.
Basic Node Setup
In the example below, the Perspective Positioner is used to unpin a perspective distorted area
of the MedianIn2 in order to paint on the flat texture. The MediaIn2 is then corner pinned back
into place. The Perspective Positioner and Corner Positioner do not concatenate, so some
softness is introduced with these nodes.
Chapter – 110 Warp Nodes 2497