Quadratic Interpolation in Hardware Rendering

Rendering systems often represent curved surfaces as a mesh of planar polygons that are shaded to add realism and to restore a smooth appearance. To increase the rendering speed, complex operations such as the solution of the rendering equation or texture transformation are executed just for a few knot points and the values at other points are interpolated. Usually linear transformation is used since it can be easily implemented in hardware. However, color distribution and texture transformation can be strongly non-linear for which linear interpolation may introduce severe artifacts. Thus this paper proposes quadratic interpolation to tackle this problem and demonstrates that it can be implemented in hardware. The software simulation and the VHDL description of the shading hardware are also presented.