Global Align Node

Global Align applies uniform transforms across the whole image to correct mechanical drift of the stereo rig (cameras that are not perfectly parallel, vertical misalignment, lens rotation). Unlike Stereo Align, which corrects area by area.

Typical workflow: Global Align first to compensate for the mechanical flaws, then Stereo Align for the remaining local drift (differential lens distortion, micro-deformations).

• Effects Library: Tools > Stereo > Global Align
• Quick add: right-click in the Node Editor → Add Tool > Stereo > Global Align

Global Align

A uniform correction across the whole image. Model: translation + rotation + scale. For mechanical rig flaws.

Stereo Align

A local pixel-by-pixel correction through vertical disparity. For optical drift (differential distortion), refraction, etc.

Recommended pipeline: Global Align (rough) → Stereo Align (fine). The reverse is possible but less clean.

• Left (orange) - the left view image.
• Right (green) - the right view image.
• Effect Mask (blue) - optional.

Full alignment pipeline:
LeftCam ─┐
         ├── Global Align (rough, mechanical)
RightCam ┘    ↓
        ┌──── Stereo Align (fine, lens)
        │      ↓
        └── [rest of the compositing] → MediaOut

Simple Roll-only correction:
LeftCam ─┐
         ├── Global Align (Right Roll = -1.5°)
RightCam ┘    → the right view comes out realigned

Before Disparity for a clean result:
LeftCam ─┐
         ├── Global Align → Stereo Align
RightCam ┘    ↓
            Disparity (clean analysis)

Right Pan (default: 0)

Horizontal translation of the right view (in pixels or relative units). To shift the convergence plane.

Right Tilt (default: 0)

Vertical translation of the right view. Corrects constant vertical disparities (cameras not at the same height).

Right Roll (default: 0)

Rotation of the right view (in degrees). Corrects a camera that is not perfectly level relative to the other.

Right Scale (default: 1.0)

Scaling of the right view. Compensates for slightly different focal lengths between the two lenses.

Apply To (default: Right)

The view to transform. Right by default (most common), but it can be Left if the left view is the one drifting.

Auto Align (default: Off)

When on, the node automatically estimates the optimal transforms. Slow, but handy as a starting point before manual adjustment.

• Correcting an amateur stereo rig - DIY rigs with small mechanical offsets: Global Align corrects them before any other processing.
• Compensating for a different focal length - two lenses not at exactly the same focal length → Right Scale compensates for the ratio.
• Vertical realignment - cameras mounted at slightly different heights → Right Tilt restores the alignment (essential for viewing comfort).
• Roll convergence correction - a "toed-in" rig (converging cameras) introduces keystone and subtle roll. Right Roll compensates for them.
• Pre-processing before Disparity - the Disparity analysis works better on well-aligned views: Global Align upstream = a cleaner disparity map.
• Convergence shift - adjusting Right Pan = shifting the screen plane (where objects appear at zero perceived depth).

• Auto Align to get started - enable Auto Align for an initial base, then turn it off and fine-tune the resulting parameters by hand.
• Always at the start of the pipeline - before Disparity, Stereo Align, or any node that analyzes the views. Otherwise, the drift cascades.
• Check visually - an anaglyph mode downstream lets you see instantly whether Global Align is correct: no vertical ghosting, no obvious roll.
• Right vs Left - by convention, you transform the right view using the left as the reference. The reverse works but is less standard.
• Visible Tilt = viewing discomfort - even a very small Tilt (1-2 px) causes eye strain over time. Always correct even small vertical offsets.
• Subtle roll is very noticeable - the human brain is sensitive to rotational misalignment. Adjust finely (in steps of 0.1° or even 0.01°).
• For complex, non-uniform flaws, Global Align is not enough - follow up with Stereo Align to correct differential optical distortion.