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Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
The prism cover test ( PCT) is an objective measurement and the gold standard in measuring strabismus, i.e. ocular misalignment, or a deviation of the eye. [1] It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components. [1]
Geometrical optics. Geometrical optics, or ray optics, is a model of optics that describes light propagation in terms of rays. The ray in geometrical optics is an abstraction useful for approximating the paths along which light propagates under certain circumstances. The simplifying assumptions of geometrical optics include that light rays:
Chroma key compositing, or chroma keying, is a visual-effects and post-production technique for compositing (layering) two or more images or video streams together based on colour hues ( chroma range). The technique has been used in many fields to remove a background from the subject of a photo or video – particularly the newscasting, motion ...
Lenticular lenses are sometimes used as corrective lenses for improving vision. A bifocal lens could be considered a simple example. Lenticular eyeglass lenses have been employed to correct extreme hyperopia (farsightedness), a condition often created by cataract surgery when lens implants are not possible.
The film is anything but a vanity project for Goldsberry, who sees her story as part of a larger cultural conversation about the difficult (and seemingly never-ending) trade-off that most parents ...
Front projection—the background is projected onto a two-way mirror, which reflects the image onto a highly reflective surface. A front projection effect is an in-camera visual effects process in film production for combining foreground performance with pre-filmed background footage. In contrast to rear projection, which projects footage onto ...
Sodium vapor process aka "yellowscreen" method. The sodium vapor process (occasionally referred to as yellowscreen) is a photochemical film technique for combining actors and background footage. It originated in the British film industry in the late 1950s and was used extensively by Walt Disney Productions in the 1960s and 1970s as an ...