Fiducial

From Wikipedia, the free encyclopedia

• In statistics, fiducial inference is a form of interval estimation developed by R.A. Fisher in connection with the Behrens-Fisher problem.

• In physics, 3D computer graphics and photography, "fiducials" or "fiduciary markers" are reference points: fixed points or lines within a scene to which other objects can be related or against which objects can be measured. Cameras outfitted with reseau plates produce these reference marks (also called reseau crosses) and are commonly used by NASA. Such marks are closely related to the timing marks used in optical mark recognition.

• In applications of augmented reality or virtual reality, "'fiducials'" are often manually applied to objects in the scenery to recognize these objects in images of the scenery. For example, to track some object, a light emitting diode can be applied to it. With the knowledge of the color of the emitted light, the object can easily be identified in the picture.

• In printed circuit board (PCB) design, "fiducial" marks, also known as circuit pattern recognition marks, allow automated assembly equipment to accurately locate and place parts on boards. These equipment locate the circuit pattern by providing common measurable points. They are usually made by leaving a spot of the board bare with a bare copper-, nickel-, or solder-coated dot inside.

• In color printing "fiducials" -- also called "registration black" -- are used at the edge of the cyan, magenta, yellow and black (CMYK) printing plates so that they can be correctly aligned with each other.

• In electrocardiography "fiducial" points are landmarks on the ECG complex such as the isoelectric line (PQ junction), and onset of individual waves such as PQRST.

• In radiotherapy "fiducial" points are landmarks in the tumour so that treatment targets the correct area of the body.

• In law the term "fiducial" means "of or pertaining to a fiduciary".