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Nieminen Juha wrote:
>
> Jerome M. BERGER <jbe### [at] enst fr> wrote:
> : But when you scale a normal
> : by 5, the way pov does it is equivalent to scaling by <5, 1, 5>
>
> Wrong. The slope doesn't change. Thus, the apparent depth is scaled by 5,
> not by 1.
No, the slope *does* change... Try it.
> To really scale the apparent depth by 1 instead of 5, the slopes would
> have to be scaled by 1/5. Povray does not do this. This is easy to test:
> Make an object with a normal modifier. Scale that object 100 times larger
> and move the camera and the light source 100 times farther away. If what
> you say was true, now the slopes would be 1/100 of the original and the
> apparent depth would have not changed, so the normal modifier should be
> almost invisible. This, of course, is not so. The slopes are not changed
> and the apparent depth gets scaled by 100 too.
I did precisely this test and if the normal is inside a normal_map I
get what you said, but if the normal is on its own it *is* almost
invisible...
> Now make this same test in megapov. What happens is that megapov will
> scale the _slopes_ by 100 as well, which means that the apparent depth
> of the surface would be 10000 after scaling.
I just did the test with megapov 0.2 and the scene was the same no
matter what scale factor I used...
Jerome
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* be done and why... * http://www.enst.fr/~jberger
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