Beam tracing

Beam tracing

Beam tracing is a derivative of the ray tracing algorithm that replaces rays, which have no thickness, with beams. Beams are shaped like unbounded pyramids, with (possibly complex) polygonal cross sections. Beam tracing was first proposed by Paul Heckbert and Pat Hanrahan [P. S. Heckbert and P. Hanrahan, "Beam tracing polygonal objects", "Computer Graphics" 18(3), 119-127 (1984).] .

In beam tracing, a pyramidal beam is initially cast through the entire viewing frustum. This initial viewing beam is intersected with each polygon in the environment, from nearest to farthest. 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 is then split up into sub-beams based on its intersection with scene geometry. Reflection and transmission (refraction) rays are also replaced by beams. This sort of implementation is rarely used, as the geometric processes involved are much more complex and therefore expensive than simply casting more rays through the pixel.

Beam tracing solves certain problems related to sampling and aliasing, which can plague conventional ray tracing. However, the additional computational complexity that beams create has made them unpopular. In recent years, increases in computer speed have made Monte Carlo algorithms like distributed ray tracing much more viable than beam tracing.

However, beam tracing has had a renaissance in the field of acoustic modelling [T. Funkhouser, I. Carlbom, G. Elko, G. Pingali, M. Sondhi, and J. West, "A beam tracing approach to acoustics modeling for interactive virtual environments", in "Proceedings of the 25th annual conference on Computer graphics and interactive techniques (SIGGRAPH'98)", 21-32 (1998).] , in which beams are used as an efficient way to track deep reflections from sound source to receiver (or vice-versa), a field where ray tracing is notoriously prone to sampling errors [A. Lehnert, "Systematic errors of the ray-tracing algorithm", "Applied Acoustics" 38, 207-221 (1993).] .

Beam tracing is related in concept to cone tracing.

ee also

*Akira Fujimoto

References


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Ray tracing (graphics) — In computer graphics, ray tracing is a technique for generating an image by tracing the path of light through pixels in an image plane. The technique is capable of producing a very high degree of photorealism; usually higher than that of typical… …   Wikipedia

  • Cone tracing — is a derivative of the ray tracing algorithm that replaces rays, which have no thickness, with cones. Cone tracing is related to beam tracing, but uses circular rather than polygonal cross sections. Cone tracing solves certain problems related to …   Wikipedia

  • Light Ray Tracing — Der Begriff Light Ray Tracing, auch Backward Ray Tracing, Forward Ray Tracing oder Light Tracing genannt, bezeichnet einen Algorithmus zur Bildsynthese, der auf Raytracing basiert. Es handelt sich dabei um eine Umkehrung des normalen Raytracing… …   Deutsch Wikipedia

  • Light tracing — Der Begriff Light Ray Tracing, auch Backward Ray Tracing, Forward Ray Tracing oder Light Tracing genannt, bezeichnet einen Algorithmus zur Bildsynthese, der auf Raytracing basiert. Es handelt sich dabei um eine Umkehrung des normalen Raytracing… …   Deutsch Wikipedia

  • Complex beam parameter — In optics, the complex beam parameter is a complex number that specifies the properties of a Gaussian beam at a particular point z along the axis of the beam. It is usually denoted by q. It can be calculated from the beam s vacuum wavelength λ0,… …   Wikipedia

  • Electron beam tomography — (EBT) is a specific form of computed axial tomography (CAT or CT) in which the X ray tube is not mechanically spun in order to rotate the source of X ray photons. This different design was explicitly developed to better image heart structures… …   Wikipedia

  • Akira Fujimoto — ] He earned BS and MS degrees in engineering from the University of Szczecin, Poland and PhD from the University of Tokyo. Since 1981 he worked for Grafica Computer Corporation, leaving it in 1986 to form his own company.In 1985 he developed the… …   Wikipedia

  • Global illumination — is a general name for a group of algorithms used in 3D computer graphics that are meant to add more realistic lighting to 3D scenes. Such algorithms take into account not only the light which comes directly from a light source ( direct… …   Wikipedia

  • Hidden surface determination — In 3D computer graphics, hidden surface determination (also known as hidden surface removal (HSR), occlusion culling (OC) or visible surface determination (VSD)) is the process used to determine which surfaces and parts of surfaces are not… …   Wikipedia

  • Screen tearing — is a phenomenon in video where a previously rendered frame overlaps a newly rendered frame, creating a look as two parts of an object (such as a wall) don t line up. This occurs when the output device sends frames out of sync with the display s… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”