A hardware accelerator for the specular intensity of Phong illumination model in 3-dimensional graphics

This paper presents a special hardware implementation developed for the computation of the specular term which is the most time consuming part in the Phong's illumination. In the Phong shading, the exponentiation operation of two floating-point numbers is necessary for each point inside a polygon. An approximation algorithm is developed to speed up the exponentiation operation, and it is supported by simple hardware that can be easily merged into a floating-point multiplier. The exponentiation operation takes just 4 cycles in the proposed hardware while it takes about 100-200 cycles in conventional floating-point units. Although an approximation algorithm is employed for the exponentiation operation, the amount of error is so minimal that the difference is virtually indistinguishable.