A gonioreflectometer is a device for measuring a bidirectional reflectance distribution function (BRDF). The device consists of a light source illuminating the material to be measured and a sensor that captures light reflected from that material. The light source should be able to illuminate and the sensor should be able to capture data from a hemisphere around the target. The hemispherical rotation

dimension In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coo ...

s of the sensor and light source are the four dimensions of the BRDF. The 'gonio' part of the word refers to the device's ability to measure at different angles. Several similar devices have been built and used to capture data for similar functions. Most of these devices use a

camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...

instead of the light intensity-measuring sensor to capture a two-dimensional sample of the target. Examples include: *a spatial gonioreflectometer for capturing the SBRDF{{What, date=April 2011 (McAllister, 2002). *a camera gantry for capturing the

light field A light field, or lightfield, is a vector-valued function, vector function that describes the amount of light flowing in every direction through every point in a space. The space of all possible ''light rays'' is given by the Five-dimensional space ...

(Levoy and Hanrahan, 1996). *an unnamed device for capturing the bidirectional texture function (Dana et al., 1999).

References

*Dana, Kristin et al. 1999. ''Reflectance and Texture of Real-World Surfaces''. in ACM Transactions on Graphics. Volume 18, Issue 1 (January, 1999). New York, NY, USA: ACM Press. Pages 1-34. *Foo, Sing Choong. 1997. ''A Gonioreflectometer for measuring the bidirectional reflectance of materials for use in illumination computations''. Masters thesis.

Cornell University Cornell University is a Private university, private Ivy League research university based in Ithaca, New York, United States. The university was co-founded by American philanthropist Ezra Cornell and historian and educator Andrew Dickson W ...

. Ithaca, New York, USA. *Levoy, Marc & Hanrahan, Pat. 1996. '' Light field rendering''. In Proceedings of the 23rd annual conference on Computer graphics and interactive techniques. *McAllister, David. 2002. ''A Generalized Surface Appearance Representation for Computer Graphics''. PhD dissertation.

University of North Carolina at Chapel Hill The University of North Carolina at Chapel Hill (UNC, UNC–Chapel Hill, or simply Carolina) is a public university, public research university in Chapel Hill, North Carolina, United States. Chartered in 1789, the university first began enrolli ...

, Department of Computer Science. Chapel Hill, USA. 118p. Computer graphics Photometry Measuring instruments