Shadow Problems

Discussions about FX-Tree and Compositing generally
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bill
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Shadow Problems

Post by bill » 17 Jun 2009, 22:03

Moderator Comment (HB):
as this thread turned out to primarily deal with Compositing-issues, I have "experimentally" moved it from "Rendering" to "Compositing"


Hi All:
I have tow questions about shadows
- How Can I Change The Color Of My Shadows When I Have A Sprite Objects In My Scene ? (like this Example)
A.jpg
A.jpg (29.46 KiB) Viewed 3476 times
- I Have A Problem with the Shadow Pass As Next
The Original Pass With Shadow Is
B.jpg
B.jpg (10.22 KiB) Viewed 3476 times
And The Result In the Shadow Pass Is A Cut Shadow And The Result Is Very Ugly When I Compose It (Like This Example)
C.jpg
C.jpg (21.04 KiB) Viewed 3476 times
Even I Checked The (Shadow cast in visible face) In the Shadow Node The Result Still Very Ugly And Not The Same In The Original Pass.
So Anybody Have Any Solution??
Thanks
Bilal Moubarak
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Hirazi Blue
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Re: Shadow Problems

Post by Hirazi Blue » 18 Jun 2009, 07:53

Concerning your first question about the colored shadow: you'll probably have to use the "simple shadow" in your render tree.
(XSIDocs > Shader Reference > Material - Illumination Shaders > Simple Shadow) :-?

The shadow pass question is slightly trickier as I am no "FX Tree"-wizard...
It all depends on how you set up your FX Tree obviously...
In a setup with no shadow in the default render, I would "comp" it, like this...
But there are probably better ways... #-o
Why? I haven't got a clue! :D
Stay safe, sane & healthy!

Deracus
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Re: Shadow Problems

Post by Deracus » 18 Jun 2009, 10:01

i think you can leave the over-node ;)

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Hirazi Blue
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Re: Shadow Problems

Post by Hirazi Blue » 18 Jun 2009, 10:06

@Deracus - you're wrong, at least depending on what you try to achieve...
leaving the "over" node out of the equation creates very harsh shadows
I however was trying to recreate the shadow my default pass with shadows gave me...
Stay safe, sane & healthy!

schyzomaniac
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Re: Shadow Problems

Post by schyzomaniac » 18 Jun 2009, 15:11

Bill, there are many ways to comp the shadow pass.
Often, you might use it only as a mask.
For example, take your diffuse pass, add a color correction, plug the shadow pass into the mask slot and then dial down the gain.
You can also take the shadow pass, invert it and then multiply with your diffuse pass. There are so many ways, it really just depends on your preferences and the look you're after.
When using it as a mask with a CC node, you can add the shadow and tint it for example in one step.

But just to clear up things. Your shadow pass looks correct. It's supposed to look like that. In some applications you will get what seems like a complete black image. But the alpha channel will reveal where your shadows are.

cheers,
Daniel

crude
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Re: Shadow Problems

Post by crude » 18 Jun 2009, 16:27

thanks hira for explanation.
I wondered often why i didn't got a good result with the shadow pass :-o

Deracus
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Re: Shadow Problems

Post by Deracus » 18 Jun 2009, 17:22

Hirazi Blue wrote:@Deracus - you're wrong, at least depending on what you try to achieve...
leaving the "over" node out of the equation creates very harsh shadows
I however was trying to recreate the shadow my default pass with shadows gave me...
Ok...with that you are right...but what i do most of the time is, render the default without any shadow...render a shadow-pass with settings, that are somewhat right...and then do the rest in the compo...without over...only with a Math Comp and sub...the amount of shadow is set by the slider in the math-comp...quick and dirty...but working for me :)
Don´t care about umbra or stuff like that anymore ;)

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bill
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Re: Shadow Problems

Post by bill » 19 Jun 2009, 23:54

Thanks Guys For Help But you create ideal examples
1- For the Shadow coloring with an ideal case i can make an override to the partition and connect a color to the shadows, but I can't use the same way when I have a Sprite object.
2- And For The shadow pass Try create an example such as my example
The Full Pass Render Result Is
Full.jpg
Full.jpg (13.16 KiB) Viewed 3391 times
And The Composite Result Is
Comp.jpg
Comp.jpg (13.27 KiB) Viewed 3391 times
Bilal Moubarak
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schyzomaniac
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Re: Shadow Problems

Post by schyzomaniac » 20 Jun 2009, 07:50

In your example, either turn the scene ambience down to zero, or render out a seperate diffuse and ambient pass. Then first combine the diffuse and shadow pass. And after that put the ambient on top of that.
Attachments
comp.jpg
comp.jpg (71.67 KiB) Viewed 3386 times

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Hirazi Blue
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Re: Shadow Problems

Post by Hirazi Blue » 20 Jun 2009, 11:01

As to shadows and sprites, just to be clear: the "simple_shadow" I was talking about isn't the same as the "shadow"-shader
(it isn't even exposed in the interface, see below,
but "lives" in the DSPreset-directory under "DSPresets\Shaders\Material\Illumination")....
I don't know if that helps, but I wanted to add it for clarity sake... ;)

below starts here ;)
In the Shader Reference in the XSIDocs the description of the "Shadow"-shader is under the header "Material Shaders", while the "Simple Shadow" is being described in the "Material - Illumination Shaders"-section. You might, looking at the Softimage-interface, wrongly, suspect, the "Shadow"-shader under "Nodes - Illumination" in the Render Tree is the same as the "Simple Shadow", talked about in the documentation under "Illumination Shaders"...

Confused? 8-} Join the club!!! :D


UPDATE: After taking some time to check, I can now confirm belatedly
there seems to be something "seriously amiss" with the "simple_shadow".
Will take me some time to figure it out, though...
Stay safe, sane & healthy!

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Hirazi Blue
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Re: Shadow Problems

Post by Hirazi Blue » 20 Jun 2009, 14:17

Okay, my attempt at colored shadows from a sprite...
I'd hardly call this a solution, it's more of a workaround I stumbled upon... b-(
Stay safe, sane & healthy!

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bill
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Re: Shadow Problems

Post by bill » 20 Jun 2009, 17:50

Thank you very much schyzomaniac And Hirazi Blue
Bilal Moubarak
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mtea
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Re: Shadow Problems

Post by mtea » 22 Jun 2009, 01:49

ehm first, you can delete the over ufo in the fxtree...second you can change color of shadow in post...for example with a color correct node and the shadow pass as a mask..much more easier than the version of hirazi and much more powerful, because you can change it directly in post...its like ao pass..don´t only use them for math composite..use them also als masks..for example the blue value is higher in areas of shadow than in other ones...

mtea
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Re: Shadow Problems

Post by mtea » 22 Jun 2009, 01:57

ah before i forget..if you want to use the shadow pass as mask, don´t make more blue into this area..go the other way and decimate the red and green value...at moment i´m working on an elaboration for professor..and i think i will put this into it too and than give it free for download..but i think you have to wait three more days:) and it is in german:) and very low level, because it is for professor:)

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Hirazi Blue
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Re: Shadow Problems

Post by Hirazi Blue » 22 Jun 2009, 09:34

Hi mtea
Could you be a little more specific? Especially about the "over" node.
I know from "another" forum ;)
you have much more experience with the FXTree ^:)^,
so I'm curious how you would solve this,
especially in light of the fact,
that leaving out the "over" node gets me a totally different result,
as I have shown earlier in this thread...

I hadn't tried to solve the "colored shadow"-problem in the FXTree,
because I set out to solve it in the Render Tree,
but I understand there are obviously more and better ways to do it. :-

And finally: the "elaboration" for your professor: is it a long text?
If it isn't, I would be willing to try to translate it, before you post it here!!! :D
(send me a PM, if you like the idea)
Stay safe, sane & healthy!

mtea
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Joined: 12 Jun 2009, 10:36

Re: Shadow Problems

Post by mtea » 22 Jun 2009, 10:51

oh mr. blue...it is near to 260 pages:) ok with a lot of pictures...at the moment i have 150 sites with 15000 words, but till wednesday i will reach 100 more sites.. but i will give it free for download here and in the other german xsi forum...

the over node only put the picture with the shadow over the picture without the shadow...it is the same if you take the math composite node and sub the shadow from the picture but not the full 100%, for example only 50%....

i´m making a small videotut only 3 minutes or so ok..but for pictures it is to much to show:) i will show a little bit more..in ten minutes or so

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