Robert L. Cook
Ray tracing, ray casting, and other forms of point sampling are
important techniques in computer graphics, but their usefulness has been
undermined by aliasing artifacts. In this paper it is shown that these
artifacts are not an inherent part of point sampling, but a consequence
of using regularly spaced samples. If the samples occur at appropropriate
nonuniformly spaced locations, frequencies above the Nyquist limit do not
alias, but instead appear as noise of the correct average intensity. This
noise is much less objectionable to our visual system than aliasing. In ray
tracing, the rays can be stochastically distributed to perform Monte Carlo
evaluation of integrals in the rendering equation. This is called distributed
ray tracing and can be used to simulate motion blur, depth of field, penumbrae,
gloss, and translucency.
Available in ACM Transactions on Graphics, Volume 6, Number 1, January 1996.