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Animating POI
The basic technique is to animate the position of the point-of-interest within the frame. If the shot bumps left suddenly, there are fewer pixels available on the left side of the point of interest to be able to maintain its relative position in the output image, and a higher zoom will be required. If we have already moved the point of interest to the left, fewer pixels are required, and less zoom is required.
Earlier, in the
Stabilization Quick Start, we remarked that the 28% zoom factor obtained by animating the rotation could be reduced further. We’ll continue that example here to show how. Re-do the quick start to completion, go to frame 178, with the Adjust tab open, in Padded display mode, with the make key button
turned on.
From the display, you can see that the red output-area rectangle is almost near the edge of the image. Grab the purple point-of-interest crosshair, and drag the red rectangle up into the middle of the image. Now everything is a lot safer. If you switch to the stabilize tab and hit Autoscale, the red rectangle enlarges—there is less zoom, as the Adjust tab shows. Only 15% zoom is now required.
By dragging the POI/red rectangle, we reduced zoom. You can see that what we did amounted to moving the POI. Hit Undo twice, and switch to the Final view.
Drag the POI down to the left, until the Delta U/V values are approximately 0.045 and -0.035. Switch back to the Padded view, and you’ll see you’ve done the same thing as before. The advantage of the padded view is that you can more easily see what you are doing, though you can get a similar effect in the Final view by increasing the margin to about 0.25, where you can see the dashed outline of the source image.
If you close the Image Prep dialog and play the shot, you will see the effect of moving the POI: a very stable shot, though the apparent subject changes over time. It can make for a more interesting shot and more creative decisions.
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