POST parameter: bug or incorrect behaviour?

[maru]

And looks like changing max sample intensity changes a lot.

[cecofuli]

You are right!!!  I'm doing more test, wait...

[cecofuli]

Mmm... Why does Max sample intensity change so much the exposition?
What do I do to obtain the correct quality lighting solution in these scene?

Exposure compensation doesn't work when I restart the render...
But if I change the MSI (from 10 to 50 for example), the scene is much bright with the same Exposure compensation
Also, if I use th esame  MSI (100 for example) with different Exposure compensation (from 1 to 4 for example) the brightness is very similar... (with Exp = 4 a little bit brighter)

I think there are something strange in the Corona Color mapping...

[Chakib]

Weird bug indeed...

[cecofuli]

With Corona light rectangular:

With Exp: 4.0 -> If I change MSI from 2 to 100 I've a little bit more bright solution

With MSI = 10
If I change Exp from 1 to 4 starting from 1 and change in realtime, the lighting brightness is very similar if I start directly from 4... the mystery increases!

(*) about the Exposition problem. I obtain a different result with the Corona Sun, but not with Corona Rectangular Light
(*) CoronaMtl emission has some problem with the Corona Color mapping and/or MSI parameter

[patoaltaco]

Cecofuli,

You are going to write "corona the complete guide" ?  :)

[cecofuli]

Ehh... Maybe =) 
One of the most parts I don't like VRay is the color mapping. Especially the famous problem with sub-pixel mapping OFF
I'm looking for a good render in CPU (cause RAM amount problem on the GPU and plug-in support).
Corona is a good renderer but it's have, as we can see, some problem too in the color mapping area :(

[cecofuli]

Here another VIDEO where you can see better all different light sources: CoronaSun, Portals, Rectangular CoronaLight and Emitters.
Only Rectangular CoronaLight  seems not to be affect by Exposure compensation (or very slightly)

SCENE DOWNLOAD

[Ondra]

ok, this is weird, MSI should not influence the result so much. I'll need to take a look at it when I am sober.

[cecofuli]

Keymaster yes, I think the same. But it could be a good start to have the Exposition parameter MSI indipendent ;-) maybe in some nightly build?
Becous eI would like to use for some interior render with artificial lights and geometry emitters.
But without this option and the MSI corrected it is difficult or impossible to do.

[cecofuli]

Maybe, this idea?

[cecofuli]

Ok, after some test,t his is my conclusion:

if you want that Corona takes into account the Exposure compensation (with Emitters Geometry an Sun), you have to raise up the MSI up to 200/400.
Corona Lights are not so influenced by MSI.  This is the only way how to do with A4.

Now my question: are there a big differences in terms of quality/errors between  MSI: 10 (default) and  up to 200/400?

[cecofuli]

[Ondra]

the exposure is preset before rendering in each case?

[cecofuli]

Yes Keymaster :) I change it before the launch of the render!
I clean up the scene and I post soon!