Calculating the reflectance map

Abstract

It appears that the development of machine vision may benefit from a detailed understanding of the imaging process. The reflectance map, showing scene radiance as a function of surface gradient, has proved to be helpful in this endeavor. The reflectance map depends both on the nature of the surface layers of the objects being imaged and the distribution of light sources. Recently, a unified approach to the specification of surface reflectance in terms of both incident and reflected beam geometry has been proposed The reflecting properties of a surface are specified in terms of the bidirectional reflectance-distribution function (BRDF).Here we derive the reflectance map in terms of the BRDF and the distribution of source radiance. A number of special cases of practical importance are developed in detail. The significance of this approach to the understanding of image formation is briefly indicated.

Comparison between detailed digital and conventional soil maps of an area with complex geology

“…The DEM was loaded into SAGA 2.0.5. (Bock et al, 2008) to calculate the terrain attributes: elevation, slope (Horn, 1981), plane of curvature (Zevenberg & Thome, 1987), curvature profile (Wood, 1996), water flux power (Moore et al, 1993), and LSfactor (Feldwisch, 1995).…”

A standard design for collecting vegetation reference spectra: Implementation and implications for data sharing

“…Simple and extended summaries of the relationship between laws of radiation, absorption and emissivity, the physics of measuring extended sources in the field and the relationship of Bidirectional Reflectance Distribution Function (BRDF) to reflectance measurements can be found in Nicodemus et al (1977), Horn and Sjoberg (1978), Silva (1978), Robinson and Biehl (1979), Duggin and Philipson (1982), Baumgardner et al (1985), Milton (1987), Deering (1989), Pinter et al (1990), Hapke (1993), Milton et al (1995), Jupp (1997), Schaepman (1998) and Rees (2001). Many of the standardised measurements are based on the bidirectional reflectance factor (BRF), summarised in Pfitzner et al (2005).…”

Numerical shape from shading and occluding boundaries

“…It can also be determined theoretically if the surfacereflectance is known as a function of the incident, emittance, and phase angles. The reflectance map can be computed, for example, if the so-called Bidirectional Reflectance Distribution Function (BRDF) [Nicodemus et al, 1977] and the distribution of light sources is known [Horn and Sjoberg, 1979].…”