Am 15.12.2013 17:23, schrieb Roman:
> On 2013-12-15 01:56, clipka wrote:
>>
>> The answer is quite simple: As various internal "fudge factors" are set
>> to 1e-6, scene details should be a good deal larger than that.
>
> Well, I can live with the fact that s=1e-6 doesn't render anything,
> although I think that POV-Ray should be free of internal absolute fudge
> factors that break scale invariance. If these are really needed, they
> should be relative so they work at any scale, or at least modifiable by
> the user.

I certainly agree on this; but weeding out those legacy fudge factors 
(they possibly have been around ever since the very first version of 
POV-Ray) needs careful consideration of the mathematical implications, 
which is a task that hasn't been tackled yet.

> The problem is that even quite large scales s>>1e-6 result in different
> images. The stripped-down scene I posted earlier might somewhat conceal
> the severity of my problem. The following closer to what I actually try
> to render: Transparent thin surfaces. Notice the vast difference in
> visual appearance depending on s=1 or s=10. Interestingly, the
> difference vanishes for thicker surfaces (e.g. 1/100 instead of 1/1000).
>
> I'm stumped. Please tell me how I can scale such thin transparent
> surfaces to get an equivalent visual.

Large. Very large.

Note that it is not your s itself that matters, but the size of the 
resulting structures. You're at 3e-5 there (for s=1), which is obviously 
still close enough to 1e-6 to give you problems.

Also note how your scene is unconventionally small anyway, with the 
primary scene content having a size in the order of 0.1 units (again at 
s=1).

I'm sorry to say this, but POV-Ray wasn't designed with this scenario in 
mind. Traditionally, scenes are designed with the primary content having 
a size in the order of 1 unit or above.

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