Camera Motion

A still image on screen for five seconds looks like a slideshow. The same image with a slow push-in looks like footage. Camera motion is that slow movement: a zoom, a pan, or both, applied to whatever is on screen during an interval.

Adding motion

Motion is added to the timeline per interval, with add_motion. It is not attached to a specific image; it applies to whatever visual is showing during that interval.

from imaginaryarts import CameraMotion

video.add_image(images[0], interval=[0, 5000])
video.add_motion(CameraMotion.KenBurns(), interval=[0, 5000])

The same motion object can be reused at many intervals. Intervals with no motion stay static.

If a motion interval covers only part of a visual's time on screen, the motion still runs correctly over the covered part. When two motion intervals overlap the same visual, the one with the larger overlap wins.

Presets

Preset	Movement
`CameraMotion.Static()`	No movement. The default when nothing is added.
`CameraMotion.KenBurns()`	A slow, linear push-in from 1.0 to 1.12. The house look.
`CameraMotion.PushIn()`	1.0 to 1.12 with ease-in-out, so it starts and ends gently.
`CameraMotion.PullOut()`	1.12 to 1.0 with ease-in-out.
`CameraMotion.PanLeft()`	Zoomed to 1.2 and held there while the frame drifts left.
`CameraMotion.PanRight()`	Same, drifting right.
`CameraMotion.PanUp()`	Same, drifting up.
`CameraMotion.PanDown()`	Same, drifting down.
`CameraMotion.ZoomInPanUp()`	Pushes in from 1.0 to 1.2 while the center drifts upward.

Custom motion

Two factories build your own. Both take an easing of "linear" or "ease-in-out".

Zoom only, centered on the frame:

CameraMotion.zoom(start=1.0, end=1.25, easing="ease-in-out")

Zoom and position. Each of start and end is a tuple of (zoom, center_x, center_y), where the centers are fractions of the frame from 0 to 1:

# Push in slightly while drifting from the lower-left toward the center.
CameraMotion.motion(
    start=(1.1, 0.40, 0.60),
    end=(1.2, 0.50, 0.50),
    easing="linear",
)

Zoom must be 1.0 or more; the frame is never scaled below its own size, so there are never empty edges.

Stills and clips

On a still image, motion is rendered with heavy supersampling so even a slow push-in moves in sub-pixel steps and stays smooth. On a video clip the same motion works, with less headroom, since every frame of a clip has to be processed. Subtle moves look best on clips; save the larger zooms for stills.