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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 109, “Miscellaneous Nodes,” in the DaVinci Resolve Reference Manual and Chapter 47 in the Fusion Reference 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 110, “Optical Flow,” in the DaVinci Resolve Reference Manual or Chapter 48 in the Fusion Reference Manual.
Advanced Optical Flow Processing
The Optical Flow, Repair Frame, and Tween nodes include a faster GPU-based Optical Flow algorithm. When you add the Optical Flow, Repair Frame, or Tween node to a comp, the Inspector includes a Method drop-down menu where you can choose Advanced to enable the GPU-based algorithm. This Advanced method is the same Optical Flow algorithm used in other DaVinci Resolve pages.
By choosing Classic from the Method drop-down menu in the Inspector, you can use the older CPU- based algorithm to maintain compatibility with comps created in previous versions. This method may also be better suited for some Stereo3D processing.