When in Dome…

The Morehead Planetarium & Science Center Production Blog

Full dome 2d compositing tricks

by Peter Althoff

November 9, 2009 | No comments | When in Dome

I figured its about time to reveal a little bit of the tricks we’ve picked up for doing simple effects on the dome that enhance the viewing experience and make production a little less 3d heavy. Granted some of these effects aren’t physically accurate, and if done to certain extremes can break the illusion of the dome space.

When using a panorama on the dome, or any type of still image, the viewer will become aware that it is a still and quickly grow board of it once it hits a static position. So to prevent a sequence from becoming static we will add a slight rotation of roughly 5 degrees or more depending on length to the entirety of a shot. What this does is keep the pixels moving on the dome surface and has a subliminal effect on the viewer. The won’t notice its there, but they’ll notice it if it wasn’t there.

Push

Another trick is using scale. Scaling a dome master or a panoramic actually translates into movement on the dome. A scale with its anchor point at the zenith translate to vertical movement up or down into a panorama. Coupling this with some images of clouds on 3d layers in after effects you can give the illusion that you’re moving up off the ground and into space without having to create a 3d scene and camera move. Another trick involving scale is to use a null object on a dome master and scale toward the point of focus. Doing this by 3-10% over the course of several seconds gives a slight push that focuses the viewer toward the source of the scale. True you’re scaling pixels and distorting the image over the dome surface, but by only increasing it by a little amount over time you’ll never notice any resolution loss, or the angular distortion that takes place. Also by offsetting your foreground and background images, i.e. your panoramic foreground and stars as your background. You can simulate the natural parallax that happens in a camera move.

ZenithScale

Keep in mind that nothing should ever really stop moving on the screen unless its an intentional freeze frame to illustrate a point. Rather than taking an object’s scale from 0-100 in 3 seconds when your sequence is 10 seconds long. Consider taking your object from 0-95 in that 3 seconds and then ease in that last 5% over the course of the remaining 7 seconds. The effect will look more polished and make your point of focus a touch more dynamic.

enjoy these video examples.


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