POV-Ray : Newsgroups : povray.newusers : Transparent Objects Become Black : Re: Transparent Objects Become Black Server Time
28 Sep 2022 13:21:29 EDT (-0400)
  Re: Transparent Objects Become Black  
From: Thomas de Groot
Date: 18 Nov 2021 07:27:27
Message: <619646af@news.povray.org>
Op 17-11-2021 om 22:06 schreef Kenneth:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> Kenneth, I have not tested it here, but are the 'voids' really
>> necessary? Is it not enough to just add the bubbles to the gel, as both
>> have different ior's and do not interact?
> Apparently, the visual result is exactly the same either way.
> Here is my own "poor man's crystal", ha-- just an intersection of three rotated
> boxes. The inclusions are simple shapes. I rendered two versions, with the
> inclusions as a UNION with the crystal vs. being DIFFERENCED from it as voids. I
> see absolutely no visual change, although I was expecting them to look
> completely different. It seems that the ior 'effect' depends only on the
> *surfaces* that the camera ray sees, not really on any imagined interior
> substance of the inclusions.
Yes, that confirms my guess. You didn't say, but I suppose that the 
'union' renders faster than the 'difference'. Additionally, using blobs 
as inclusions, especially if there are many of them, will speed up 
render time.

> I have not yet tested my scene to discover how the different iors affect each
> other-- i.e., simple addition vs. multiplication of the iors. That's difficult
> to tell, visually. I suspect that it's just addition.
I am not sure. It looks like that - independent from ior - the used 
media inside container and inclusions are treated separately. In my 
experiments I do no see any cross-influence, addition or multiplication, 
of colors.

> -----
> BTW, this 'multiple-ior' effect gave me an idea-- which I am experimenting
> with-- about creating what looks like *variable* ior within an object, that
> changes along its length or depth, etc. The basic idea is to pre-slice the
> object into *many* very thin box sections, each with a slightly increasing ior
> value, then re-combine the slices to look like the original solid object. Of
> course, I am running into coincident-surface problems with all of those slice
> recombinations... but I think that's a temporary problem, until I figure out how
> best to re-position them. (Should they be separated by tiny 'air' gaps-- or
> should they be slightly embedded into each other?) Anyway, my experiments look
> promising so far, if a bit...odd ;-)
I am interested to see the result.

@bubble_person: sorry if this discussion 'seems' to ignore you. This is 
not the intention nor the reality; Your original question generated a 
number of issues which we are not sure about, and I think everybody will 
benefit in the end.


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