fog with light beams

# 1 21-10-2009 , 09:57 PM

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Hi, I´m working on a interior image which should be animated.
That means the light should be aniamted, if possible!!! user added image

my vision is that the sun illuminates the floor and the table and fills the room with light, a normal day so! user added image

but the trick is that the light should be visible(sfumato)
or better materialised light through dust in the air and the tree outside is moving because of the wind outside.

The final image is a still where the light shows a specific atmospheare trough the play of light!

the image below shows a right way, but the beams are made with Photoshop, because directional lights don´t supports fog and with spots I don´t get good results.

My idea is really to render that playing light, because of the moving tree, the resulting floo illuminating, the visible beams.

has somebody any advice how to create that effect?
if I don´t had tryed every possible way I know. than I wouldn´t ask! Please help me, because I think it could be get a very nice project!

thanks and goog day! user added image

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# 2 21-10-2009 , 10:31 PM

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Well just as you did with this image you could do the fog in post. There are even the MR volume shaders. Care to show what results you got with the spotlight?

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# 3 22-10-2009 , 01:21 PM

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I didn´t saved any image with spot light fog, but the problem is the cone shape fog, sunlight is parallel which spot light rays are not!

I think the "post way" is a problem because of the light on the floor and table! Its then a hand animating job, because this visible light is also moving and fog is only visible where DIRECT light rays are passing the scene.

if there was a feature in maya, that the global fog would cast depth map shadows and is only visible where light rays are too, then it were awesome! but there must be another way, probably the MR shader user added image

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# 4 22-10-2009 , 02:30 PM

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Here's a spot light with fog. I added fractal to the light color. Took less than a minute to make this. Not sure if this would give you the results you want. The hardest part would be to pull the spot light point of origin far enough away from the window so that the rays look more straight.

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# 5 22-10-2009 , 07:37 PM

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Floze did some lighting tutorials, might come in handy for this..>>>Lighting Tut<<<

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# 6 23-10-2009 , 08:51 AM

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hi, thanks you for the replys and @GecT, the tuts are awesome, I will use them..

But now I´m a little bit further in depth with this problem.

below you see the first pic which is made with maya software which has rendered pretty well, what I´m looking for!
Perfecto the fractal is a good idea, but how you see I wantet that effekt through real geometry! in that case a tree.
and that light and fog penetrated through the tree gives a nice atmosphere, for what my efforts are! user added image

It were to nice if there wasn´t one problem!
the second image shows the same scene rendered with mental ray and the disturbed render. the tree is converted to a mesh, that MR can read and setting aren´t responsible for that "mistake" ! user added image

I tryed out the settings...

What could we do to render that with mental ray, because the final scene includes FG GI SunSKy.

hope I explained everything fine and you can follow my vision for that aniamtion...

It must get finished, I will!!! user added image

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# 7 23-10-2009 , 08:53 AM

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the mental image... user added image

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# 8 23-10-2009 , 06:00 PM

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I understand what you mean. I'll recreate your scene and see if I can figure anything out for you when I get off work which should be about 3-4 hours after this post.

I'm not totally familiar with light fog so I'll need to experiment too. My first thought is that it might have something to do with shadows but when I look closer at your 2nd render..it doesn't look like the fog is going through the window and also that the light is hitting the inside of the wall where it shouldn't...hmm. Atm, I'm clueless.

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# 9 23-10-2009 , 06:21 PM

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Not sure if this is related to the issue at hand, but I remember hearing that light fog does not work that well with raytracing shadows, they work better with depth map. I don't know exactly what the issue is with raytracing shadows and light fog though.

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# 10 23-10-2009 , 07:35 PM

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The problem is with the depth map shadows and MR. So its not you lol.

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# 11 24-10-2009 , 07:22 AM

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yeah, i figured out that you can't use raytrace shadows with light fog. And with depthmap shadows you have to do some tweaking in the render settings but it eventually won't give good results. I did find this youtube vid that might be of some use.

https://www.youtube.com/watch?v=TekaB3OMbGI

it's not in English but you should still be able to figure out what he's doing. Oh yeah, when he assigns a material to the box...he's clicking on transmat in the list...bottom of the list for me.

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# 12 25-10-2009 , 01:17 PM

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hey great tut, thats what I´m looking for!!!
And the language isn´t english but german! user added image

lol cool!

Thanks Perfecto, GecT and the others for your investigation of time! That thread will finish the projekt! user added image

I did knew about Raytrace shadows and dmaps...
In my images there are dmaps used!
The way of doing fog in that tut is more naturally and MR does a good job in being naturally, because in real world lights don´t emit fog too, like the way I tryed. But with that cube and transmat... way you have a exact and easy way to make light rays visible, where they are schould! Great great great stuff!

I never had so much response with a thread.
I had a lot of stuff to do last days, so I couldn´t work further more, but I will do today and update that thread with new results..

thanks a lot

Last edited by Mayastatic; 25-10-2009 at 01:26 PM.

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fog with light beams

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