Merge3D

Merge3D is not the 3D equivalent of a normal 2D Merge in terms of Background and Foreground. It does not blend pixels or establish layer order. Connected elements share one three-dimensional environment and interact according to real position, camera framing, materials, lighting and depth.

SceneInput[#] is a dynamic input set. The node keeps free inputs available and adds new ones as connections are made, so the scene is not limited to a fixed pair of sockets. Text3D, Shape3D, ImagePlane3D, Camera3D, SpotLight/PointLight/DirectionalLight and another Merge3D can all enter the same node.

Merge3D inputs are multicolored because they represent different elements inside a 3D scene, but semantically they all carry scene3d data. They are not image inputs: MediaIn, Background or Fast Noise must first become part of a 3D element, for example through ImagePlane3D or a material workflow.

SceneInput1, SceneInput2 and SceneInput3 do not define which object is on top. Visibility is determined by spatial position, camera framing, clipping, culling and material opacity. This is fundamentally different from Foreground/Background on a normal Merge.

Merge3D nodes can be nested. For example, several Shape3D parts can be assembled into Logo_Merge and that complete scene can then feed Scene_Merge alongside a camera, lights and other objects. This structure improves readability and creates a real transform hierarchy.

The Merge3D Transform tab applies to the complete scene entering that node. Translation offsets the group, Rotation turns it around Pivot, and Scale resizes the whole group. Each child keeps its local transform underneath that parent-level transform.

This group transform is one of the foundations of parenting in Fusion 3D. When two objects must always move together, it is usually cleaner to group them in one Merge3D and animate one parent transform instead of duplicating matching keys on each child.

Pass Through Lights controls whether lights cross the boundary of a particular Merge3D into downstream hierarchy levels. By default, a light introduced inside one group does not have to illuminate geometry introduced later in another Merge3D. This makes local lighting groups possible.

When Pass Through Lights is enabled on a nested Merge3D, its lights continue through the output scene and can affect geometry introduced downstream. The option is therefore important in multi-Merge scenes, projector setups and compositions that need separate lighting zones.

Pass Through Lights is not a global Enabled switch for a light. It does not turn a disabled SpotLight back on and does not change Intensity or Color. It only controls whether existing light objects cross this Merge3D boundary.

Merge3D-specific Controls are deliberately minimal: Pass Through Lights is effectively the only dedicated option. Most staging work lives in the shared Transform tab.

Translation Pick and Rotation Pick provide viewer-assisted transform sampling. Manual XYZ values are sufficient for most scenes, while Pick is useful when position or orientation needs to be acquired from compatible 3D/auxiliary data.

Rotation Order selects XYZ, XZY, YXZ, YZX, ZXY or ZYX evaluation. A single-axis turn usually looks the same, but large multi-axis rotations depend on this order, so it should be treated as part of the rig before animation begins.

Pivot does not translate the children by itself. It changes the point used by the Merge3D parent Rotation and Scale. For an orbit, hinge, carousel or rotating logo, establish Pivot before animating Rotation.

Scale is locked uniformly by default through Lock X/Y/Z. Unlocking exposes separate X/Y/Z Scale controls for non-uniform scaling of the complete group. This is a scene transform and is distinct from procedural Size or Radius inside Shape3D.

Use Target switches the Merge3D orientation into a target-driven mode: the group rotates to face an XYZ target and Rotation becomes relative to that target. It is useful for aim-style rigs, while plain Rotation is easier to reason about for a simple static group.

Import Transform imports transform data only from supported 3D scene formats; it does not import geometry, lights or cameras. Full external 3D content belongs in FBX/Alembic import workflows instead.

Merge3D output stays scene3d. It can feed another Merge3D, Transform3D, Override3D, Renderer3D or another 3D processor. Normal Merge, Glow, ColorCorrector and MediaOut belong after Renderer3D, when scene3d has become image data.

Several cameras can exist inside one merged scene. Merge3D simply carries them as scene elements; the Renderer3D/camera selection path determines which view becomes the final image.

For debugging, think in group boundaries: inspect each child Merge3D, then the final Merge3D, then Renderer3D. If an object disappears after nesting, inspect transform hierarchy, camera/frustum and lighting boundaries before trying to compensate with material changes.

A good Merge3D structure is not one giant node containing everything. Logical groups for title, product, environment and final scene usually make transforms, lighting and debugging far more predictable.