Notch Reference Manual

Optical Flow

Method

This node attempts to analyse an image and visualise the movement of objects in the scene, using different techniques depending on the mode selected.

Attributes

Name Description
Preview In Viewport Preview the effect blended with alpha in the viewport.
Preview RGB In Viewport Preview the RGB values in the viewport.
Preview Alpha In Viewport Preview the alpha values in the viewport.
Previous Frame Blend How much of the previous frames blend with the current frame.
Previous Frame Directional Dependence How much the directional movement of the previous frame affects the current frame.
Num Levels How many levels of motion can be tracked.
Optical Flow Mode Change the way the optical flow motion is calculated.
  • High Quality, Uses a block matching algorithm for reasonably accurate tracking.
  • Motion Vector Estimate, Generates smoother motion vectors but far less accurate.
  • High Speed, A simple technique using gradients and frame differences. Less accurate than High Quality, but much faster.
Output Velocity Magnitudes Forces the output to only show the magnitude. This only affects the output image, and not the internal motion vectors.
Output Velocity Angle And Magnitude Outputs both the velocity angle and magnitudes. This only affects the output image, and not the internal motion vectors.
Optical Flow Scale Scale the movement that is output.
Num Dilate Passes How many times the dilate pass is run.

Inputs

Name Description Typical Node Input
Effect Mask Mask out areas that Post-FX applied to this node won’t be applied. Video Loader
Alpha Image Add an image to control the alpha values of the image. Video Loader

Outputs

This node outputs either an image or a set of motion vectors depending on the context.