Smallgantics is a digital post production technique used for miniature faking – simulating miniature cinematography on full scale filmed sequences – created and developed by Bent Image Lab. The technique was inspired by the tilt-shift photography of Olivo Barbieri, and Ray Di Carlo's hands on observations while building photo real miniatures in Hollywood. Noticing that certain details had to be avoided when creating believable miniatures, Di Carlo pondered what could be achieved by introducing these same flaws into live action footage, virtually reversing the quality control process. After his initial tests, this technique was further developed by the Bent production team, including VFX director Jim Clark, into a complex, hand matted motion process on multiple planes.
Smallgantics is a digital image process that accurately simulates miniature depth of field (DOF) on full-scale filmed subjects via a "hand-made" digital application of miniature flaws. Artificial depth planes, up to 8 layers, are generated by the artist, which distort with each frame of a sequence, giving the artist complete control of a simulated miniature DOF scenario.
In comparison to Smallgantics, tilt-shift photography is a photography technique that can be used to give footage - still and motion - the illusion of miniature DOF, but it is not an accurate representation. Using a tilt lens the plane of focus can be tilted between the front of the lens and the film plane of the camera, making the top and bottom, or both sides of the image drop focus. Usually the same lens has both tilt and shift capability but only tilting is needed for the miniature effect.
With tilting, the top and bottom of tall buildings/objects often appear incorrectly out of focus because the blurring of the image is not based on the distance from the lens to the subject, as true DOF does. To accurately recreate miniature DOF with full-scale cinematography, depending on the distance to, and the scale of your subject, one would require a lens in the magnitude of 1000mm+ with a massive glass surface large enough to visually encompass the entire subject.
With Olivo Barbieri's method, which also tricks the eye into seeing a real landscape as miniature via the shift-tilt method, certain objects in the frame betray the illusion. For example: a telephone pole extending vertically from the bottom to the top of frame will appear soft focus at the bottom, sharp focus in the middle and return to soft focus at the top. In reality, because the telephone pole is within a single plane in 3D space, the degree of focus should remain constant from top to bottom - this is what Smallgantics attempts to accurately simulate.
The Smallgantics process begins with artists creating as many as eight planes of z-buffering over live-action footage, on a frame by frame basis, resulting in an animated black and white matte sequence. The artist draws these matte sequences around each object in the scene then assigns z-plane focus parameters. Larger objects may have to be subdivided between z-planes because their depth falls into multiple planes of focus. These depth mattes are then seamlessly blended together with varying degrees of blur, creating the effect of a shallow depth of field. A more sophisticated use of the Smallgantics technique allows the animator/compositor to rack, or change, focus within the image over time.
The shift-tilt reverse Scheimpflug principle has been used for more than a decade, making Smallgantics a computer generated variation of an existing optical technique.