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[REQ] Additional 10 Light Layers!!

Posted: Wed Sep 07, 2011 7:52 am
by davidbaird
We render interiors where the entire space is shown in lieu of partial settings.

Typically this involves views to many different spaces & spaces that require many different lighting types (beam spreads, intensity, color) using IES files in addition to emitter materials.

2 current projects include a very large Chapel & a Night Club, both of which use dramatic lighting effects to create atmosphere for their intended purposes.

We could easily use another 10 light layers for control.
We are always doubling up lights on the same layer & then try to adjust with different IES files

Of course we do not know how another 10 light layers will affect rendering speed, even though we network render on 24 cores most of the time. Even 10 layers can make rendering slow sometimes if we are trying to also use an env map for a "dusk" night time scene

We use Skindigo plug-in.

Thanks

Re: [REQ] Additional 10 Light Layers!!

Posted: Wed Sep 07, 2011 9:40 am
by Zom-B
davidbaird wrote:Of course we do not know how another 10 light layers will affect rendering speed, even though we network render on 24 cores most of the time. Even 10 layers can make rendering slow sometimes if we are trying to also use an env map for a "dusk" night time scene.
Actually Light Layers shouldn't slow down your rendering speed! But you maybe have noticed that some layers stay noisy, and others render fine.
This is due to Indigos importance handling of light materials: Brighter = more important => more CPU time!
A layer with 1000 times more "luminous flux" gets 1000 times more CPU time, or told different, the other layer only gets 0,1% and will take 1000 times longer to get the same Samples per pixel!

Anyway, using additional light layers can easily fill your RAM, since each Light Layer is like a own IGI file,
so here some math:

A 1200 x 1200 px IGI file takes ~17MB
Adding super sampling raises the Size by 4 for each step
A SuperSampling value of 2 already takes 68MB
We use a value of 3 for that example with a final IGI size of 17 * (1+4+4) = 153 MB

Using 10 layers we'll end up with 1530MB of IGI size, with 20 layers you are at 3GB of RAM usage!!!
This for only a 1200x1200px image, not counting in RAM usage for meshes (rather small), textures (super high since textures get loaded in RAM in RAW pixel format!) and used 32bit EnvMaps (super mega high RAM usage, like textures but even way more since in 32bit!).

So take care that your network nodes can handle the huge file sizes anyway :)

Re: [REQ] Additional 10 Light Layers!!

Posted: Wed Sep 07, 2011 10:05 am
by davidbaird
Thanks Zom-B

That explains a lot!

No wonder those combined artificial & env map lighting scenes take so long & can still be noisy even after reducing them to about 1000x600.

Our main work station is a dual 6 core 3.0gz w/24gb ram (we use this as the master) & the other 3 are quad core 3.0gz w/8gb ram (nodes)....& render over night & over weekends. Some scenes need the weekend.

With your information we are more aware to plan better to meet deadlines!

Re: [REQ] Additional 10 Light Layers!!

Posted: Wed Sep 07, 2011 10:18 am
by Zom-B
davidbaird wrote:No wonder those combined artificial & env map lighting scenes take so long & can still be noisy even after reducing them to about 1000x600.
there is a simple workaround for the noisy lightLayers:
Raise the light power in your scene lets say 10 times, then during rendering reduce LightLayer intensity to 0.1 and you should have same brightness as before, but faster rendering of this layer and less noise in the final image.
(This can be driven further if needed like raising by 100 and reducing to 0.01...)

Using this opportunity I would like to request a small numeral info beside a LightLayer about its actual Lumen Flux value :)

Re: [REQ] Additional 10 Light Layers!!

Posted: Wed Sep 07, 2011 11:50 am
by davidbaird
That makes sense.
I think we have been doing that a little bit to keep the lights from being "blown out" & loosing detail.
We will certainly need to be more aware of this in the future.
Now that I know about the effects that various light power has on speed I understand why different scenes process at drastically different speeds.

The lumen meter in the light layers is a good idea.
Thanks