Editing Spatial anti-aliasing (section)

==Object-based anti-aliasing==

A graphics rendering system creates an image based on objects constructed of polygonal primitives; the aliasing effects in the image can be reduced by applying an anti-aliasing scheme only to the areas of the image representing silhouette edges of the objects. The silhouette edges are anti-aliased by creating anti-aliasing primitives which vary in opacity. These anti-aliasing primitives are joined to the [[silhouette edge|silhouetted edges]], and create a region in the image where the objects appear to blend into the background. The method has some important advantages over classical methods based on the [[accumulation buffer]]{{clarify|date=March 2012}} since it generates full-scene anti-aliasing in only two passes and does not require the use of additional memory required by the accumulation buffer. Object-based anti-aliasing was first developed at [[Silicon Graphics]] for their [[SGI Indy|Indy]] workstation.