Smallgantics

From Wikipedia, the free encyclopedia
Jump to: navigation, search
HarrowdownHill Factory.jpg

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.

Definition[edit]

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. 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.

Technical Explanation[edit]

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.

Process[edit]

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.

References[edit]

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.

History[edit]

Smallgantics was created by Bent Image lab and used for the first time in a series of helicopter sequences in the Thom Yorke music video "Harrowdown Hill", directed by Chel White and produced at Bent Image Lab.

Alternative techniques[edit]

Example[edit]

Before
After

References[edit]