Shooting Requirements for 3-D Effects

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‌Shooting Requirements for 3-D Effects ‌

You’ve seen how to track a simple demo shot. How about your own shots? Not every shot is suitable for match-moving. If you can not look at the shot and have a rough idea of where the camera went and where the objects are, SynthEyes won’t be able to either. It’s helpful to understand what is needed to get a good match-move, to know what can be done and what can’t, and sometimes to help a project’s director or camera-person plan the shots for effects insertion.

This list suggests what is necessary:

 The camera must physically change location: a simple pan, tilt, or zoom is not enough for 3-D scene reconstruction. If you have a hand-held camera, and point it in different directions, that will not be enough camera translation: you need to walk!

 Depth of scene: everything can not be the same distance, or very far, from the camera.

 Distinct trackable features in the shot (reflected highlights from lights do not

count and must be avoided).

 The trackable features should not all be in the same plane, for example, they should not all be on a flat floor or green-screen on the back wall.

 If at all possible, shoot progressive, not interlaced footage. Interlaced footage has only half the vertical resolution, twice as many frames to worry about, and is like using floppy disks or Windows 98.

If the camera did not move, then either

 You must need only the motion of a single object that occupies much of the screen while moving nontrivially in 3-D (maybe a few objects at film resolution),

 Or, you must make do with a “2½ -D” match-move, which will track the camera’s panning, tilting, and zooming, but can not report the distance to any point,

 Or, you must shoot some separate still or video imagery where the camera does move, which can be used to determine the 3-D location of features tracked in the primary shot.

For this second group of cases, if the camera spins around on a tripod, it is IMPOSSIBLE, even in theory, to determine how far away anything is. This is not a bug. SynthEyes’ tripod tracking mode will help you insert 3-D objects in such tripod shots anyway. The axis alignment system will help you place 3-D objects in the scene correctly. It can also solve pure lock-off shots.

If the camera was on a tripod, but shoots a single moving object, such as bus driving by, you may be able to recover the camera pan/tilt plus the 3-D motion of the bus relative the camera. This would let you insert a beast clawing into the top of the bus, for example.

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