Bidirectional reflectance distribution function

Let Nobj be the normal vector of the patch, let N/, be the normal vector that points to the direction of the light source, and let Ny be the normal vector that points to the direction of the viewer. Let / (N/.) be the irradiance falling onto the patch, and L(Ny) be the radiance leaving the patch in the direction of the viewer. The fraction of the radiance relative to the irradiance falling onto the patch is called the bidirectional reflectance distribution function... 

Figure 3.14 The bidirectional reflectance distribution function (BRDF) specifies how much of the incident light coming from direction (6l,

Sometimes it is important to consider the direction of reflected irradiation exitent from a surface. A property called the bidirectional reflectance distribution function (BRDF) is used to specify the directional distribution of the reflected intensity for a specified direction of incident radiation [2-4]. A specular surface is a mirrorlike surface for which the incidence angle is equal to the reflection angle. For a diffusely reflecting surface, the reflected intensity is the same in all directions, and if perfectly reflective, the BRDF is l/n sr. ... 

The reflected spectral radiance depends on the distribution of the surrounding radiation incident on the target and the bidirectional reflectance distribution function of the target, and except for well-controlled environments or in some limited cases, is difficult to determine. 

Bidirectional reflectance distribution function (BRDF) n. The ratio of radiance per unit irradiance, used for describing the... 

The reflectance properties of a surface are characterized by its bidirectional reflectance distribution function (BRDF). The BRDF is the ratio of the scene radiance in the direction of the observer to the irradiance due to a Hght source from a given direction. It captures how bright a surface will appear when viewed from a given direction and illuminated by another. For example, for a flat Lambertian surface illuminated by a distant point light source, the BRDF is constant hence, the surface appears equally bright from all directions. For a flat specular (mirrorHke) surface, the BRDF is an impulse function as determined by the laws of reflection. 

Stuhlinger, T. Bidirectional reflectance distribution function of gold-plated sandpaper. Optical Eng. 22, SR-142 and Lea, T. K., and Schotland, R. M. (1988). Infrared retroreflecting lidar calibration targets. Appl. Optics 27, 208. Discuss gold-plated sandpaper, once widely used as standard for mid-IR diffuse reflectance. 

BIDIRECTIONAL REFLECTANCE DISTRIBUTION FUNCTION AS A MEASURE OF OPTICAL SCATTER... 

I. Introduction Significance and Use of the Bidirectional Reflectance Distribution Function ... 

This chapter explains how to characterize the angular distribution of optical scatter from an opaque surface. In particular it focuses on measurement of the bidirectional reflectance distribution function (BRDF). BRDF is a convenient and well-accepted means of expressing optical scatter levels for many purposes (1, 2). 

Bartell, F. O., Dereniak, E. L., and Wolfe, W. L. (1980). The theory and measurement of bidirectional reflectance distribution function (BRDF) and bidirectional transmittance distribution function (BTDF). In Radiation Scattering in Optical Systems, Vol. 257, p. 154. SPIE. 

Bidirectional reflectance distribution function (light) Black sooty crap... 

Compilation of infrared emissivity and/or reflectivity data is difficult because of the volume of potential data One really needs the reflectance as a function of surface material, preparation, wavelength, and incident and exit angles. (Refer to the discussion of bidirectional reflectance distribution function in Section 14.3.5.)... 

To characterize reflection that is not perfectly specular, we use the bidirectional reflectance distribution function (BRDF). This function converts irradiance on a surface to the reflected radiance L from that surface ... 

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