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.