William F Pokorny , dans le message <5eb2e4cd$1@news.povray.org>, a

> Have you looked at bounding mode 2 (+bm2)? If not that's worth a shot.

I just tried with 20k spheres, it did not make a visible difference.

> Related: There are issues in v37 and the official v38 branch - mitigated 
> 'somewhat' in my povr solver branch - with tiny sphere intersections 
> getting dropped when they should not be. Applies to a few other objects 
> too a situations too. Depends on exactly how the rays approach.
> 
> This can affect Anti-Aliasing time somewhat substantially because the 
> spheres are basically blinking in and out of existence...  There is, 
> IIRC, some related discussion buried in the github pull req #358 comments.
> 
> https://github.com/POV-Ray/povray/pull/358

I am using the version packages by Debian, they say it is a 3.7.0.8. Anyway,
you tell me there is a problem with sphere intersections, but my scene only
has merges, so I should be safe?

What I am really asking is:

merge {
  A
  B
}

merge {
  merge { A }
  merge { B }
}

where A and B are small and made of many tiny objects close together, but
they are far apart from each other.

Will the second version be faster because POV-Ray will compute a bounding
box for the two sub-merges, or shall I write:

merge {
  merge { A bounded_by box_A }
  merge { B bounded_by box_B }
}

?

I shall test, but it would be helpful to know what is supposed to be the
result.

Thanks for your help.

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