ANR Track To Locked Camera

Overview

Track To Locked Camera turns 2D motion into a small 3D setup. Put it under a Tracker, Transform or CornerPin (or a chain of them) and Copy Camera + Card pastes a Camera that never moves, a Card that moves so that, seen through that camera, it lands every frame where the track puts the picture, an Axis riding on the card at the track's point, and optionally a ScanlineRender wired to both.

Use it when a 3D element (particles, text, geometry, a projection) has to follow a 2D track and a full camera solve is more than the shot needs. Plug an image into the Card and render it through the camera: the result is the 2D match-move, now in 3D space.

A 2D move cannot show depth, so its change of scale has to go somewhere. Scale Becomes: Distance keeps the card's size and brings it nearer as the track grows, a real 3D move. Card Size keeps the card at Distance and makes it bigger. Translate, rotate and scale come across exactly; skew and perspective, which a flat card in front of a fixed lens cannot always hold, are fitted on the corners and Status says how far off they are.

Inputs

1. Sourcerequired

   The output of the Tracker, Transform or CornerPin whose motion you want. The node reads that node, and the chain above it, by following this input upwards.

Output. The picture from above, untouched. In the viewer the node draws where the card lands on this frame (a square on its bottom-left corner) and the track's point (a cross).

Quick start

1. Add ANR Track To Locked Camera directly under your Tracker, Transform or CornerPin.
2. Set Frame Range, and choose Scale Becomes and Card Area (Full Frame for a whole-picture card, Around Track for a square Card Size pixels wide around the track's point).
3. Leave Focal Length, Horizontal Aperture and Distance at their defaults unless you need a particular lens or scale.
4. Press Copy Camera + Card, click in the Node Graph and press Ctrl+V.
5. Connect your texture to the pasted Card's input and view the pasted ScanlineRender: the texture moves with the track.
6. Read Status: it says whether the card lands exactly on the motion or how many pixels the corners are off.

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

• Use the pasted Axis to attach other 3D elements to the tracked point: it sits on the card at that point on every frame.
• Tick Invert when the node above is a stabilise and you want the match-move, or the other way round.
• With a Tracker, the node uses its Transform tab when that is keyed. Otherwise it works the move out from the tracks themselves, from the Tracker's reference frame, using each track's T, R and S boxes (rotate and scale need at least two tracks).
• Turn off With ScanlineRender if you only want the Camera, Card and Axis.

Good to know

• The node walks up through Tracker, Transform and CornerPin nodes and simple nodes between them (Dots, colour corrections, Crops and similar). A Tracker ends the chain; any other node stops it.
• The track's point is the centre of the Tracker's T tracks on its reference frame, a Transform's center, or the centre of a CornerPin's from corners, taken from the node at the top of the chain.
• Frames with no track data, and frames where the motion would put the card behind the camera, are left out. Status counts them.
• Focal Length only changes how a card with perspective tilts; it does not change where the card lands.

Works with

ANR Transform ConvertCollapses a chain of CornerPins and Transforms into one CornerPin, Tracker or Transform keyed on every frame, or its inverse.ANR Card To TrackTurns a 3D Card seen through a camera into 2D: a Tracker with its four corners, a CornerPin, or a live matte of the card.ANR AI Point TrackerTracks points through a shot with an AI tracker or a classical pattern tracker, carries hidden points through occlusions, and exports a Nuke Tracker or CameraTracker.ANR AI Planar TrackerPlanar tracking of flat surfaces from masks you draw, with layered masks, a correction layer, and exports to Roto, a four-corner Tracker or a Card and Camera.