I have an old povray scene that I'm trying to tidy up, and one of the things is
to optimize rendering times by reducing the number of light sources. Currently
there are 44 point lights, which I think it probably excessive. Most of them are
inside background objects (multistorey buildings in the background), and
probably could be gotten rid of?

What are some general guidelines on optimizing light sources in a povray scene?
Is there some trick I could use to retain approximately the same look but with
less light sources (or with better rendering performance)?  Does povray optimize
away faraway fading light? E.g., if a background building is far away then only
objects close to it would involve that light source, but other objects in the
scene would skip that light source?

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"tutki" <nomail@nomail> wrote:
> I have an old povray scene that I'm trying to tidy up, and one of the things is
> to optimize rendering times by reducing the number of light sources. Currently
> there are 44 point lights, which I think it probably excessive. Most of them are
> inside background objects (multistorey buildings in the background), and
> probably could be gotten rid of?
>
> What are some general guidelines on optimizing light sources in a povray scene?
> Is there some trick I could use to retain approximately the same look but with
> less light sources (or with better rendering performance)?  Does povray optimize
> away faraway fading light? E.g., if a background building is far away then only
> objects close to it would involve that light source, but other objects in the
> scene would skip that light source?

I think what you are needing is light groups.
3.4.4.2 Light Group in the help file
Have Fun!

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"Leroy" <whe### [at] gmailcom> wrote:
> "tutki" <nomail@nomail> wrote:
> > I have an old povray scene that I'm trying to tidy up, and one of the things is
> > to optimize rendering times by reducing the number of light sources. Currently
> > there are 44 point lights, which I think it probably excessive. Most of them are
> > inside background objects (multistorey buildings in the background), and
> > probably could be gotten rid of?
> >
> > What are some general guidelines on optimizing light sources in a povray scene?
> > Is there some trick I could use to retain approximately the same look but with
> > less light sources (or with better rendering performance)?  Does povray optimize
> > away faraway fading light? E.g., if a background building is far away then only
> > objects close to it would involve that light source, but other objects in the
> > scene would skip that light source?
>
> I think what you are needing is light groups.
> 3.4.4.2 Light Group in the help file
> Have Fun!

Thanks, light groups are indeed what I had in mind.

Unfortunately, a quick test with grouping objects in my scene into light groups
revealed that the speedup is only minimal: around 13.4 seconds render time
without light groups, 13.2 seconds with light groups.

I probably have to simplify some of my global lights, though. And also reduce
the amount of reflective surfaces. :D  I think in this old scene I got carried
away with the polished chrome surfaces so there's too much reflection going on.

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Op 03/02/2022 om 21:05 schreef tutki:
> I have an old povray scene that I'm trying to tidy up, and one of the things is
> to optimize rendering times by reducing the number of light sources. Currently
> there are 44 point lights, which I think it probably excessive. Most of them are
> inside background objects (multistorey buildings in the background), and
> probably could be gotten rid of?
> 
> What are some general guidelines on optimizing light sources in a povray scene?
> Is there some trick I could use to retain approximately the same look but with
> less light sources (or with better rendering performance)?  Does povray optimize
> away faraway fading light? E.g., if a background building is far away then only
> objects close to it would involve that light source, but other objects in the
> scene would skip that light source?
> 
> 
Something you could try is to replace those point lights in the 
background buildings by tiny, white spheres with finish {emission 1}. 
You can increase the emission value up to your needs.

-- 
Thomas

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Le 2022-02-03 à 15:05, tutki a écrit :
> I have an old povray scene that I'm trying to tidy up, and one of the things is
> to optimize rendering times by reducing the number of light sources. Currently
> there are 44 point lights, which I think it probably excessive. Most of them are
> inside background objects (multistorey buildings in the background), and
> probably could be gotten rid of?
> 
> What are some general guidelines on optimizing light sources in a povray scene?
> Is there some trick I could use to retain approximately the same look but with
> less light sources (or with better rendering performance)?  Does povray optimize
> away faraway fading light? E.g., if a background building is far away then only
> objects close to it would involve that light source, but other objects in the
> scene would skip that light source?
> 
> 
For those lights situated inside background buildings, you can replace 
them with textures with an emission value. Make sure that those textures 
are entirely and only inside the buildings.
You may need to add some boxes inside those buildings to achieve that.

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Alain Martel <kua### [at] videotronca> wrote:
[...]
> For those lights situated inside background buildings, you can replace
> them with textures with an emission value. Make sure that those textures
> are entirely and only inside the buildings.
> You may need to add some boxes inside those buildings to achieve that.

Thanks! I'll definitely look into this.

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