Object Solver Constraint

The Object Solver constraint makes a Blender object imitate the motion of a real-world object.

Usage

Start by loading a video file into the Movie Clip Editor, registering the physical object in the Objects Panel, and using motion tracking to track at least eight markers on that physical object. Then use Solve Camera/Object Motion to reconstruct the motion of the physical object, and finally add this constraint to a Blender object.

Options

../../../_images/animation_constraints_motion-tracking_object-solver_panel.png

Object Solver constraint.

Active Clip

Whether the physical object is in the scene’s Active Clip. If unchecked, a selector appears for choosing another clip.

Object

The physical object whose motion to imitate. See the Objects Panel in the Movie Clip Editor’s Sidebar for setting this up.

Camera

The Blender camera matching the physical camera that recorded the object. If left empty, the scene’s active camera is used.

If the physical camera was in motion, the Blender camera should have a Camera Solver Constraint. This constraint is useful even if the physical camera was stationary, because it makes the tracking markers appear at their reconstructed world positions in the 3D Viewport (if the Motion Tracking overlay is enabled).

Set Inverse

Tell the constraint that the current Location of the Blender object (that is, its position with the constraint disabled) is the correct position for the current frame. Once this information is saved, the object will also be in the correct position for the other frames.

  • When initially adding the constraint:

    • Bring the object into position for the current frame.

    • Add the constraint.

    • Click Set Inverse.

  • When tweaking the object’s position at a later point:

    • Run Apply Visual Transform. (This may move the object to a different position.)

    • Disable the constraint. (This will bring the object back to its previous position.)

    • Tweak the object’s position as desired.

    • Click Set Inverse.

    • Enable the constraint.

Clear Inverse

Resets the relative transformation that was stored by Set Inverse.

Constraint to F-Curve

Replaces the constraint by a set of equivalent keyframes.

Influence

How strongly the constraint affects its owner.