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Lightbeam (called Collusion in its experimental version) was an add-on for Firefox that displays third party tracking cookies placed on the user's computer while visiting various websites. It displays a graph of the interactions and connections of sites visited and the tracking sites to which they provide information. [2]
Each polygon that intersects with the beam must be visible, and is removed from the shape of the beam and added to a render queue. When a beam intersects with a reflective or refractive polygon, a new beam is created in a similar fashion to ray-tracing. A variant of beam tracing casts a pyramidal beam through each pixel of the image plane. This ...
It might also reflect all or part of the light ray, in one or more directions. If the surface has any transparent or translucent properties, it refracts a portion of the light beam into itself in a different direction while absorbing some (or all) of the spectrum (and possibly altering the color). Less commonly, a surface may absorb some ...
A light beam or beam of light is a directional projection of light energy radiating from a light source. Sunlight forms a light beam (a sunbeam) when filtered through media such as clouds, foliage, or windows. To artificially produce a light beam, a lamp and a parabolic reflector is used in many lighting devices such as spotlights, car ...
Modeling photon propagation with Monte Carlo methods is a flexible yet rigorous approach to simulate photon transport. In the method, local rules of photon transport are expressed as probability distributions which describe the step size of photon movement between sites of photon-matter interaction and the angles of deflection in a photon's trajectory when a scattering event occurs.
The beam wander and jitter can be measured by tracking the centroid or peak of the beam on a CCD beam profiler. The CCD frame rate is typically 30 frames per second and therefore can capture beam jitter that is slower than 30 Hz—it cannot see fast vibrations due to one's voice, 60 Hz fan motor hum, or other sources of fast vibrations.
The targets are known as "retroreflective" because they reflect the laser beam back in the same direction it came from (in this case, back to the laser tracker). One type of target in common use is called a spherically mounted retroreflector (SMR), [ 5 ] which resembles a ball bearing with mirrored surfaces cut into it.
The first non-intrusive eye-trackers were built by Guy Thomas Buswell in Chicago, using beams of light that were reflected on the eye, then recording on film. Buswell made systematic studies into reading [3] [4] and picture viewing. [5] In the 1950s, Alfred L. Yarbus [6] performed eye tracking research, and his 1967 book is often quoted. He ...