| 摘要 |
PURPOSE:To properly express a feeling of a light source by dividing a large light source into plural regions. CONSTITUTION:A filament is divided into plural regions and respective regions 1a, 1b, 1c are set at the seventh decimal point or less, preferably tenth decimal point or less of the distance to a reflecting surface or the like so that each region is small enough to be handled as a point light source. While approximation of the point light sources is thus utilized, a feeling of a lengthy light source can be expressed. A large light source is thus divided into such size as to be capable of being regarded as a point light source and brightness on a predetermined surface is calculated at each region and stored on a table and thereby the intensity on a target surface is stored together with the vector of reflected light and can be used as the base of subsequent calculations. A feeling of a large light source can thus be expressed properly via simple calculations. |
