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 Post subject: Re: Sky Shader issue
PostPosted: 17 Jan 2011, 14:13 
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Hi Nizar,

Yes, after some fiddling with the volume light I found out the same thing ;)

I'll try to post my thoughts on the video somewhere at the end of the day, including some workarounds for some stuff.

For the Sun/Sky system, like Max stated, it was designed to be 'physically correct', and work in tandem with the architectural shader.
All light FX are basically all tricks..
And the Sun/Sky system is contolled by the position of the sunlight, just in real life. That's all the control you get.


rob

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 Post subject: Re: Sky Shader issue
PostPosted: 17 Jan 2011, 14:51 
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Quote:
Yes, after some fiddling with the volume light I found out the same thing ;)


Ok, so I'm not totally stupid :D

Quote:
I'll try to post my thoughts on the video somewhere at the end of the day, including some workarounds for some stuff.


Thanks very much! :ymapplause:

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 Post subject: Re: Sky Shader issue
PostPosted: 17 Jan 2011, 19:39 
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Hi,

I had some time to look at it before work found me again ;)

Here are some thoughts/notes:

Part 1 - Sunlight system:
- A tonemapper is now added to the renderpass in SI2011, and that is heavily changing the values for the lighting. Be sure to turn check your gamma correction in the preferences or tonemapper.
- The system is different from XSI 701, and now properly interlinked with sky.
- No value slider for the brightness for the sun. This is controlled by the position of the sunlight. Higher is brighter, lower less bright.
- Also the brightnes of the sky color changes when moving the sun. Like the real thing ;)
- FG has to be turned on for the Sun/Sky system to work properly.
- Shadow is turned on by default in Sun/Sky system

Part 2 - Volume Spotlight:
- You don't have to use the Area Light option for Soft shadows in SI2011. You can also use the Raytraces Soft Shadows option now with some low values forSoftness ands samples.
- Or still use the Area Light option and change it's values so it looks good.
- The volume/tonemapper combo is more or less broken, or never meant to work together. It's like mixing old and new.
You can test it though on a new scene without any Sun/Sky system or mia_tonemapper to the pass.
- Volume property. the values needed are way smaller now than the ones needed in the PPG or video. Start off with something like .04 for the Reflectance to get something similar.
- But it's better to use something like the parti_vol shader on the pass>volume to get similar results. Try creating a separate pass for this, so you can tweak it later in a comp.

I'll have a look later on, but I have to get to work now ;)

hope it helps,

rob

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 Post subject: Re: Sky Shader issue
PostPosted: 18 Jan 2011, 00:30 
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Quote:
- No value slider for the brightness for the sun. This is controlled by the position of the sunlight. Higher is brighter, lower less bright.
- Also the brightnes of the sky color changes when moving the sun. Like the real thing ;)


Nice, but IMHO a bit awkward, in Modo i.e., you can setting manual day time (insert hour, month ecc.)

Thanks very much for your help :)

Actually I have another issue: importons and final gathering cannot be used together? If I doing I receive an error message: "scene 04 warn 072134: importons and final gathering are on, globillum off", any idea about? This "globillum" do not compare in F1 help pdf
In tutorial are used together without any error message.

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 Post subject: Re: Sky Shader issue
PostPosted: 23 Jan 2011, 20:42 
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Did anyone already log this issue with the volumic property as a potential bug officially?

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 Post subject: Re: Sky Shader issue
PostPosted: 24 Jan 2011, 00:15 
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The volumetric is a problem only if you use physical sky, in other condition it work fine. So I don't know if it is a bug or not. IMHO, the real issue is in physical sky, pretty useless.

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 Post subject: Re: Sky Shader issue
PostPosted: 24 Jan 2011, 10:17 
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Well, I wouldn't say it's useless, as the new setup for "physical sun/sky" actually does seem to mimic something resembling a true physical sun/sky, while the old system just wasn't up to that task at all. The issue I am referring to specifically here is the fact that the "photographic exposure" (that is created as part of the sun/sky setup) and the "volumetric property" do not mix. I've tried all kinds of values for both and even removing the "photographic exposure" from the setup altogether, but nothing really worked. Rork is quite probably right, that they were "never meant to work together", but unless there is some kind of confirmation from Softimage itself - even just a mention in the User's Guide that these two items don't mix - I would still consider the behavior of the "volumic property" in conjunction with the "photographic exposure" a bug. A minor one, perhaps, but still a bug...

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 Post subject: Re: Sky Shader issue
PostPosted: 24 Jan 2011, 10:34 
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Understood, ok, I think it is a bug.

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