Motion vectors and animation

Motion vectors and animation

Motion vectors are used by V-Nova PresenZ to smooth the motion of animated objects in the volumetric movie at display time.

This allows the player to interpolate the animation at any time between the frames recorded in the volumetric movie. This is particularly handy in VR, since the display refresh rate of the VR headset is usually completely different from the framerate of the movie. For instance a VR headset might have a display refresh rate of 90 Hz while the movie is 24 fps. In that example the headset will ask for those first frames in the movie: 0 , 0.2666, 0.5333, 0.8, 1.0666, ... The interpolation system of V-Nova PresenZ based on the motion vector can display the proper state of the animation at those non-integer frames, giving a perfectly smooth experience to the VR user.

Motion vectors hold local information about the motion of each point for each frame. The motion vectors can be computed by most rendering engines and can be incorporated into a compositing software.

V-Nova PresenZ requires a specific type of motion vector that describes the trajectory of objects from the current frame to the next frame. Basically for each point: motion vector(frame) = position (frame+1) - position (frame)

Note: Our authoring plugins can detect when the rendering is in an animation context and will prompt the user to apply the motion vector settings automatically.

Warning: Attention, don't confuse the motion vector concept with the "velocity" in simulation dynamics. The motion vector we are looking for is the vector pointing to the position at the next frame , while the velocity is the current speed of the object at the beginning of the frame simulated before any external force is applied (gravity, wind, etc).