Macro Scale Portable Bi-directional Reflectance Distribution Function (BRDF) Instrumentation

"The Bidirectional Reflectance Distribution Function (BRDF) is a far more accurate description of the way real surfaces reflect light than is the Hemispherical Directional Reflectance (HDR), which is a global average. Use of the BRDF to describe thereflectance of objects therefore results in a very significant increase in realism when used for rendered objects. Traditionally, however, instruments that measure the BRDF use small aperature illumination, usually much less than one inch. Theseinstruments therefore measure only the small scale BRDF characteristics of surfaces. Many natural and man-made objects, however (such as tree bark, rocks, and 3-D surface treatments), have surface features larger than can be handled using small spot sizeillumination. The military, therefore, has a need for a field portable instrument with a much larger illumination size than is currently available. The objective of this project is to develop a bi-directional reflectometer capable of measuring theselarge scale vehicle and background terrain reflectances for use in combat vehicle signature analysis. Such an instrument would have great value not only for the Army in characterizing the signature of military vehicles and natural backgrounds but also forany commerical application requiring realistic renderings of objects or surfaces with large surface features.The objective of Phase I is to develop a methodology and hardware concept for a field port