Smooth Motion Node

Smooth Motion uses precomputed motion vectors (Vector, Back Vector) to smooth the selected channel over time. It removes frame-to-frame fluctuations that do not match real motion (temporal noise, flickering edges).

It is limited to the channels available in the image (RGBA, Disparity, Vectors, Normals, Z). The input must have precomputed Vector and Back Vector channels (from an Optical Flow node or an EXR with vector data).

• Effects Library: Tools > Optical Flow > Smooth Motion
• Quick add: right-click in the Node Editor → Add Tool > Optical Flow > Smooth Motion

• Input (orange) - a 2D image sequence with precomputed Vector and Back Vector channels. No vectors = no effect (but no error either).

Stereo cleanup of disparity edges:
LeftCam ─┐
         ├── Disparity → Optical Flow
RightCam ┘                ↓
                  Smooth Motion (Channel = Disparity)
                          → MediaOut
   = disparity edges that are more stable over time

Smoothing vectors before Vector Distortion:
MediaIn → Optical Flow → Smooth Motion (Channel = Vector + Back Vector)
                       → Vector Distortion
                       → MediaOut

Two-node technique for erratic motion:
MediaIn → Optical Flow ─┐
                        ├── Smooth Motion (vectors)
                        │           ↓
                        │   Smooth Motion (other channels
                        │                   using the smoothed vectors)
                        └─────────────────────────┘
                                    ↓
                                  MediaOut

Channel (multi-select checkboxes)

Selects the AOV channels to smooth: RGBA, Disparity, Vectors, Normals, Z-depth. Missing channels do not cause an error (no-op).

Settings (shared OF)

Standard optical flow parameters: Smoothness, Search Range, etc. (documented on the Optical Flow node).

The Settings tab is shared with the other Optical Flow nodes, exposing blending, masking channels and common options:

Blend (0.0 - 1.0)

Mix between the original input and the smoothed result. Lets you tone down the smoothing if it is too strong.

Process When Blend Is 0.0

Processes the node even when Blend = 0 (scripted operations).

RGBA Channel Selectors

Limit the smoothing to specific channels (e.g. only Alpha for stereo edge cleanup).

Apply Mask Inverted / Multiply by Mask

Options to invert or multiply by the mask channel.

Use Object / Use Material

Enables the Object/Material IDs of EXR files as masks. Sliders and a Sample button.

Correct Edges

Edge handling toggle for multi-object images.

Hide Incoming Connections

Hides the wires for a clean graph.

Comments / Scripts

Node annotation + 3 render-time script fields.

• Stereo 3D edge cleanup - smooths the Disparity channel to remove the temporal fringing visible at the edges of stereo objects.
• Smoothing motion vectors - unstable vectors on noisy footage: Smooth Motion cleans them up before other nodes use them (Vector Distortion, Vector Motion Blur).
• Stabilizing AOVs frame to frame - normals / Z flickering on a noisy 3D render: temporal smoothing for stability.
• Multi-node workflows - two Smooth Motion nodes in a row (first smooth the vectors, then smooth the target channels with those vectors) for scenes with erratic motion.
• Stereo VFX pipeline - disparity integration + Smooth Motion = a professional workflow for broadcast stereo 3D compositing.

• Precomputed vectors required - an Optical Flow upstream is mandatory, or an EXR with exported vector data. Without it, the node does nothing.
• Smoothing vectors directly = sometimes worse - on erratic motion, smoothing the vectors directly can make the result worse. Test both approaches.
• Two-node technique - for complex shots: one Smooth Motion for the vectors, another for the target channels. It uses the smoothed vectors.
• Cache upstream - Optical Flow + Smooth Motion = very heavy. Cache the Optical Flow to avoid recomputing on every tweak.
• Balanced Smoothness - too much = loss of fine detail, not enough = visible artifacts. Test it shot by shot.
• For truly pathological cases (chaotic, very fast motion), consider a classic 2D stabilizer in parallel.