Viewpoint specification is fundamental to traditional computer graphics rendering. Both the transformation of a scene to eye space in the traditional graphics pipeline and the origination of viewing rays in a ray-casting system depend on the viewpoint. Moreover, many subsequent rendering steps are also impacted by the choice of viewpoint, including clipping, projection, illumination calculations, shading, and visibility determination. As a result, changing the viewpoint frequently gates the entire process of interactive rendering, as each rendered frame is initiated with the specification of a viewpoint, followed by the scene description, and culminating with the final displayed image.
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