A novel BRDF measurement technique with spatial resolution-dependent spectral variance

Overhead spectral imaging has enabled a variety of quantitative remote sensing techniques. However, the derived surface reflectance upon which these techniques rely is generally directional and dependent upon the incident solar and receiving detector angles. The bidirectional reflectance distribution function (BRDF) is becoming increasingly important with the development of non-nadir, multi-angle systems. A BRDF measurement approach in the visible to near infrared is described which is suitable for field use. An imaging technique measures BRDF but also enables the generation of the BRDF variability, or the bidirectional reflectance variance function (BRVF). From the measurements, the BRVF and spectral correlation statistics may be produced which are tailored to a sensor's point spread function. Spectral BRDF and BRVF may then be incorporated into spectral algorithms or used for synthetic image generation having accurate spatial and spectral variability, which is of great interest for exercising spectral algorithms.