On 27 Jul 2000 12:26:59 -0400, Warp wrote:
>Tom Melly <tom### [at] tomandluf9couk> wrote:
>:>   For many function this can be analytically impossible to calculate.
>
>: So what is POV doing? Does it calculate the surface in some way that doesn't
>: depend on "knowing" where the surface is?
>
>  Povray uses a stochastic algorithm, ie. it takes many samples and tries
>to approximate the right value. It will seldom hit the mathematically exact
>value.
>  (This as far as I have understood correctly the isosurface raytracing.)

Well, it's not technically stochastic.  Stochastic implies some degree of
(pseudo)randomness.  POV (Well, MegaPOV, and future versions of POV) does 
use a numerical algorithm, and thus is susceptible to error, but it's 
deterministic and the error can be bounded to be as small as you want to,
within the limits of your machine's FP precision.

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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