Nieminen Juha <war### [at] punarastascstutfi> wrote...
>   I tried the blinn highlight but didn't see much difference with
specular.
> I didn't see why it's more realistic or better.
>   Could someone post an image (to p.b.i) clearly showing the difference
> between specular and blinn in the same object?

Honestly, I didn't see much of a difference either.  However, blinn
highlights are a much better estimate for some surfaces, and are based on
statistics and physical properties.  Specular and phong are just estimates.

Basically, when people created the specular and phong models, the said, "The
surface looks like this.  How can I design my model so it produces similar
output."  So both of those models are just guesses that look fairly good.

When people created torrance+sparrow+blinn+cook highlight model, they said,
"On the microscopic level, we can describe the surface like this.  If the
surface does look like that, then we can use statistics, coupled with the
fresnel reflectivity function to determine how much light is reflected back
for each angle.  Then, if we did our math correctly, our model will produce
output that looks real."

The differences between blinn and specular are subtle, but then again,
motion blur, focal blur, and radiosity are all subtle when used correctly,
and they can add a lot to realism.

-Nathan

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