Locator 3D Node

Locator 3D takes a 3D point (an absolute XYZ position or the position of a target object) and converts it into 2D screen space coordinates through a given camera. It publishes this 2D position as a number output, usable through Connect To on any 2D control (ellipse center, the position of a Transform, the input of a Tracker).

Typical case: making a 2D text or HUD follow a 3D element moving in the scene, without manual tracking.

• Effects Library: Tools > 3D > Locator 3D
• Quick add: right-click in the Node Editor → Add Tool > 3D > Locator 3D

• SceneInput (orange) - required. The output of a 3D scene that contains the camera to use for the projection.
• Target (green) - optional. Another 3D object. When connected, the Locator automatically sits at the center of that object, and the XYZ sliders then work in local coordinates relative to that object.

Place Locator 3D after the Merge 3D that contains the camera - otherwise the camera is not in the scene reaching the Locator, and the projection can't happen.

1. Merge 3D with camera + objects
2. → Locator 3D (orange input)
3. → (optional) Renderer 3D if you also want the visual render

The Locator is a "pass-through" node - it doesn't break the 3D stream, and it can be placed anywhere between the Merge and the Renderer.

Position parameters

Position X / Y / Z (in Fusion units, default: 0 / 0 / 0)

Coordinates of the point to project. Without a Target, in world space; with a Target, in coordinates local to the object.

Sub-Pixel Position (default: on)

Enables sub-pixel precision for the output values (avoids "staircasing" when driving a tracker).

Use Alpha

Takes alpha into account in visibility calculations.

Camera parameters

Camera

Dropdown menu listing every camera in the scene reaching the Locator. This is the camera whose point of view is used to project the 3D point into 2D.

Use Frame Format Settings (default: on)

Forces Width/Height/Aspect to match the composition preferences. Recommended to avoid mismatches between the project resolution and the Locator resolution.

Width / Height / Pixel Aspect

Output dimensions used for the projection. They must match those of the final Renderer 3D, otherwise the 2D point will come out at the wrong coordinates.

Display parameters (3D viewer)

Size

Size of the crosshair shown in the 3D viewer.

Color

Crosshair color.

Make Renderable

Makes the crosshair visible in an OpenGL viewer.

Unseen by Camera

When checked (and Make Renderable is on), the crosshair shows in the 3D viewer but not in the final render through Renderer 3D.

Matte

Makes the Locator invisible, along with anything it occludes.

Sub ID

Selects an individual element within a geometry (a character of a 3D text, a copy from a Duplicate, …).

Connecting a 3D object to the green Target input deeply changes how the Locator behaves:

• The transform center becomes the position of the target object.
• The XYZ sliders become local offsets relative to that object.
• When the object moves (animation, parenting), the Locator moves with it without any animation of its own.

This is the way to "stick" a 2D overlay to a 3D object for good, even if that object changes position because of an upstream node.

The Locator publishes a 2D Position output (X, Y normalized or in pixels depending on the settings). To use it:

1. On the 2D node that consumes it (an Ellipse Mask, a Transform, …), right-click the Center control.
2. Choose Connect To > Locator 3D > Position.
3. The control is now driven by the Locator. No more keyframes to set.

• HUD that follows a 3D object - Target on the object's node, local position at [0, 2, 0] (above it), then Connect To the position of a 2D Text+. The text follows the object even if it rotates or moves.
• Labels on several objects - one Locator per object, each publishes its 2D position, and each Text+ hooks onto it.
• Mask tracking through 3D - instead of tracking a mask manually in 2D, attach its center to a Locator that follows a 3D point. Reliable even if the subject temporarily leaves the frame (as long as the camera and the object are known).
• Lens flare on a 3D light - place a Locator at the position of a Point Light and plug its output into the center of a 2D flare effect.
• 2D particle driver - the 2D position of a Locator drives the spawn point of a pEmitter's particles.

• Consistent Width/Height - pitfall #1: if your Renderer 3D renders at 1920×1080 but the Locator is at 1280×720, the 2D position will be offset. Enable Use Frame Format Settings to guarantee consistency.
• Off-screen point - if the 3D point is behind the camera or outside the frustum, the 2D position can fall outside [0, resolution]. Add clamping logic on the consuming nodes if that is a problem.
• Occlusion - the Locator always projects the point, even when it is hidden behind another object. To handle "hidden/visible" states, look at the renderer side instead (render/z-depth pass).
• Animated camera - the Locator recomputes every frame. Smooth animation, no baking needed.
• If you have several cameras in the same scene, double-check that the Camera menu points to the right one - it is an easy silent mistake.
• For visual debugging, enable Make Renderable + a colored crosshair, then turn off Unseen by Camera to see the point in the final render.