User Manual

Table Of Contents
Optical Flow Workflows
The Optical Flow analysis is a non real-time process, and depending on your computer, the
clip’s resolution, and the duration of the clip, it can take some time. Because of this, the general
idea is that you pre-generate the motion vectors, either by performing the analysis overnight or
using a render farm, and save results into an OpenEXR sequence. The Optical Flow toolset is
designed around four types of nodes that either generate, destroy, pass through, or construct
the motion vectors.
OpticalFlow
The Optical Flow node generates the Vector and BackVector data. Typically, for optimal
performance, you connect the Optical Flow output to a Saver to save the image as OpenEXR
files with the motion vectors stored in an aux channel.
TimeSpeed, TimeStretcher
You can create smooth constant or variable slow-motion effects using the TimeSpeed or
TimeStretcher nodes. When Optical Flow motion vectors are available in the aux channel of an
image, enabling Flow mode in the TimeSpeed or TimeStretcher Interpolation settings will take
advantage of the Vector and BackVector channels. For the Flow mode to work, there must be
either an upstream OpticalFlow node generating the hidden channels or an OpenEXR Loader
bringing these channels in. These nodes use the Vector/BackVector data to do interpolation on
the motion channel and then destroy the data on output since the input Vector/BackVector
channels are invalid. For more detail on TimeSpeed or TimeStretcher see Chapter 100,
“Miscellaneous Nodes” in the DaVinci Resolve manual and Chapter 49 in the Fusion manual.
SmoothMotion
SmoothMotion can be used to smooth the Vector and BackVector channels or smooth the
disparity in a stereo 3D clip. This node passes through, modifies, or generates new aux
channels, but does not destroy them.
Repair Frame, Tween
The Tween and Repair Frame nodes are different from standard optical flow nodes because
they have the OpticalFlow analysis and motion vector generation built in. Tween will compare
two frames and create an in-between frame, which is good for recreating a missing or flawed
frame. Repair Frame will look at frames on either side of the current frame and repair scratches,
dust marks, and so on. Because these nodes work with flow values between non-sequential
frames, they cannot use the optical flow stored in the input image’s Vector/BackVector
channels, but rather must regenerate the flow of each frame, do their processing, and then
destroy the flow channels. This being the case, these nodes are computationally expensive.
For more detail on Tween or Repair Frame, see Chapter 101, “Optical Flow” in the
DaVinci Resolve manual and Chapter 50 in the Fusion Studio manual.
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