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Bluesilver
08-28-2008, 04:53 PM
As far as I understood from big studios showreels, they add atmosphere thickness (mostly blue) in compositing softwares using depth maps.

My question; Is it possible to add a thick atmosphere in Lw render like in Vue renders ? I think Vue can output a seperate pass for this purpose. Otherwise, if you recommend to do it in compositing package, can you recommend a tutorial for using depth maps in order to achive bluish thick atmosphere ?

Thanks.

Giacomo99
08-28-2008, 05:17 PM
You can do it using the Fog (Windows--Volumetrics and Fog Options) settings. Unlike many other tools in Lightwave, it is completely self-explanatory and easy to use.

Dodgy
08-28-2008, 05:39 PM
There's the Fog options in the Volumetric panel, and Ground Fog as a volumetric plugin.

Bluesilver
08-28-2008, 05:56 PM
Thank you very much.

and, what about to make same effect in compositing in order to have more control. Is it true that they are using depth pass for atmosphere thickness effect? I know, it is possible to control depth value with PSD export from Lw. But I don't know how to apply these greyscale depth pass to achive a bluish thick air in Aftereffects.

A bit clue or a small tutorial (link) would be much appreciated.

Thanks again.

Dodgy
08-28-2008, 06:41 PM
If it's afterfx, you're on your own. You can do it in LW though using the nodal image filter in conjunction with the saved render and corresponding depth buffer.

Bluesilver
08-28-2008, 06:51 PM
If it's afterfx, you're on your own. You can do it in LW though using the nodal image filter in conjunction with the saved render and corresponding depth buffer.

Really !!! I didn't know this Dodgy. Please can you explain a bit more because I am not good at Lw nodes yet. I always prefer Lw's render first.
It sounds that nodes will give same or more control than Afterfx.

Thanks Dodgy and waiting your reply.

Mr Rid
08-28-2008, 06:59 PM
Fog doesnt get along with transparency. One crazy thing Ive done for 'atmosphere' is to parent a volumetric distant light to the camera which allows for some interesting control.

Yes, in production we usually make depth maps for atmosphere that can be altered much easier in the comp. For a depth pass, you can just render an all black version of your geometry over a white background, with a white linear fog with min falloff at the closest vertice to camera and max falloff at the furthest vertice from camera. This can be used as an alpha to control atmosphere applied as color, sat, or contrast (or any tool) in 2D. An EXR will particularly allow fine levels adjustment to effectively slide the fog back and forth as well as increase/decrease the atmosphere on the Z.

Dodgy
08-28-2008, 07:21 PM
Here's a simple node setup. You'll need the node image filter plugin from here:
http://pagesperso-orange.fr/dpont/plugins/nodes/Additionnal_Nodes_2.html

As you can see, it's just the colour image, and the zbuffer fed into a gradient node, which uses the zbuffer as the input to fade in a colour.

Bluesilver
08-28-2008, 08:19 PM
Thank you very much Mr Rid.
I will try your depth pass trick especially with EXR output in 2D. I am sure this will give me final control while compositing.

Thank you very much Dodgy.
Your sample scene and plugin link is much appreciated. Your help reminded me that I should learn Nodes in Lw in depth. It seems there are almost endless possibilities to make final render great in Lw if I learn Nodes.

Thanks for both of you guys. You don't know how much you helped me tonight.