> scaling the normals big gives you a very smooth
> result, ... Naturally you need a rather high amount
> of samples in order to get a good-looking result
> with normals scaled big.

Yes, and so many samples are too slow. With just a few samples, the normals
are pointing in all kinds of wrong directions considering the true surface.

> When scaled small, the result looks grainy no matter
> how many samples you use (even though a larger
> amount of samples still gives a visually better result).

In theory yes, sure. But as you said, more samples gives a smooth result. I
just did an experiment based on Chris Huff's explanation: I'm rendering the
"bolts and plugs" scene again, this time I changed the reflective textures
to have 3 averaged normals instead of one with HQ anti-alias over the entire
scene.. It was good at first, faster, but now it hangs at the bottom of the
picture... This part still render and it will break the 2-hour limit
(compared to my posted picture).

It must be because adc_bailout and max_trace_level doesn't come and save the
day.. Now there are 3 normals to average no matter what.. The ping-pong goes
on inside the metal for the red plug... My old method also had ping-pong,
but there was only 1 normal to evaluate, so adc_bailout had more effect, so
to say.

The visual result is almost the same, but a tad worse because there are some
white spots, so for now I think my old method was the best one.

Regards,
Hugo

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