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Computer Graphic Rendering of Material Surfaces |
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Computer Graphic Rendering of Material Surfaces |
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NEFDS
The Nonconventional Exploitation Factors Data System (NEFDS) is a database of surface reflection parameters built upon a modified form of the Beard-Maxwell model, the NEF Beard-Maxwell (NEF-BM) model. NEFDS contains a suite of programs which use the database to perform complex radiometric calculations while taking into consideration the properties of the target material, the material background, the measuring sensors, and the atmospheric environment. The database contains pre-measured surface reflection parameters for over 400 materials corresponding to a wide variety of objects ranging from camouflage to white paint. Of key importance to this project, additional surface reflection parameters of other materials can be determined and used with NEFDS because a measurement protocol, using existing radiometric instruments, has been specified.
The large selection of pre-measured materials fall into 12 different categories: asphalt, brick, camouflage, composite, concrete, fabric, water, metal, paint, rubber, soil and wood. A NEFDS utility can be used to query for BRDF values of any of these materials at a range of wavelengths and any given geometry. The variation of material BRDFs available through NEFDS can be seen in Figure 2 below, which shows a visualization of the queried BRDFs of cement and lumber. Notice the significant difference in geometry that can be characterized by the modified Beard-Maxwell reflection model. This difference is also quite evident in the images rendered using the NEFDS protocol.
Figure 2: BRDFs of cement (left) and bare construction lumber (right) obtained from NEFDS. For more information on NEFDS contact National Image and Mapping Agency (NIMA)
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