| 摘要 |
PURPOSE:To shorten the time required for picture generation by calculating a luminance value between two points with the interpolation calculation processing is the case of coincidence between the object to which the point of luminance calculation belongs and the object to which the preceding point of luminance calculation belongs. CONSTITUTION:The intersection between a tracing light beam and object data is obtained by an intersection calculating means 4, and a point of luminance calculation is obtained by a luminance calculation point calculating means 5, and it is decided by a decision means 9 whether this object data is equal to object data where luminance calculation is performed at the just preceding point of luminance calculation or not. If said obtained point is on the surface of the same object, luminance values of picture elements between both points are obtained in a luminance interpolating means 11 by interpolation calculation; but it is on a different object, luminance values of respective picture elements between both points are faithfully obtained one by one by the luminance calculation processing. Since the luminance calculation processing is spatially and discretely performed in the part where the surface of the object to be displayed is not changed, the luminance calculation processing more than necessary is omitted and the processing time is shortened.
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