ANR Light Match

Overview

Light Match watches the plate behind your element. On the Reference Frame, the frame where you graded the element to sit right, nothing changes. On every other frame, each Foreground pixel changes by what the wall point behind it changed since the Reference Frame: a passing shadow, a flicker, a light switched off.

The node follows the wall point behind the element by itself, from the element's own motion (for example the CornerPin that places it), or from a tracker connected to the Track input. Light Size ignores the wall's own detail, such as a window frame or a sign, so it does not print through the element, while shadow edges stay sharp.

The Blacks section moves the element's black point onto the plate's, for haze, flare or a lifted black level.

Inputs

1. Foregroundrequired

   The element you are compositing (a patch, a sign, a CG render), already placed where it sits on the plate. Its alpha says where it is.

2. Backgroundrequired

   The plate the element sits on. Its change since the Reference Frame is what the node applies to the Foreground.

3. Maskoptional

   Limits where the change is applied. Invert Mask applies it outside the mask instead.

4. Trackoptional

   A Tracker, CornerPin, Transform or moving 3D card setup that moves with the element. When it is connected, the node follows the wall behind the Foreground with it; otherwise it uses the Foreground's own motion.

Output. The Foreground with the plate's light change applied, ready to merge over the plate. Output can also show the change on its own or the reference plate, for checking.

Quick start

1. Place your element over the plate as usual, and grade it so it sits right on one frame.
2. Add ANR Light Match. Connect the placed element to Foreground and the plate to Background.
3. Go to the frame you graded on and press Set Reference Frame To Current. On that frame the Foreground passes through unchanged.
4. Play the shot: the element now follows the plate's light. Choose a Change mode: Difference for flicker on a bright wall, Ratio when the light multiplies the surface, Gain + Offset for black-outs, shadows and haze.
5. If the wall's own pattern shows through the element, raise Light Size; if a small patch of light or shadow is missed, lower it.
6. Merge the result over the plate as before.

The panel

The node's panel as Nuke shows it, with the values of a new node. Click any control to see what it does; tabs and sections work as in Nuke.

All controls

Tips

• Set Output to Change to see only what the node adds, and check that it comes from the right place on the wall.
• Output > Reference Plate shows the plate of the Reference Frame moved to now. Inside the Foreground it should show the same wall as the plate now; if it slides, connect a tracker to Track.
• Pick Blacks: Behind Foreground measures the plate only under the element (its alpha, or the Mask), which is best when the plate's black level differs across the frame.
• Strength scales the change; Mix blends the result with the untouched Foreground.

Good to know

• Nothing changes on the Reference Frame, by design: that is the frame you matched by eye.
• With Ratio, a background that goes fully black makes the Foreground black. Gain + Offset handles black-outs and lifted blacks more naturally.
• The node needs to see the Foreground once on the Reference Frame (view that frame, or press Set Reference Frame To Current) before it can follow a moving element.

Works with

ANR Black MatchMoves a comped element's blacks onto the plate's, and keeps them there when the plate's blacks drift with exposure, flicker or haze.ANR Interactive LightLights an element with footage of a fire, lightning or a screen, through its normals and depth, with shadows from its own shape or from smoke.