Vray Passes and composite help

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  04 April 2010
Vray Passes and composite help

Posted in the After Effects forum but think it might get a better reply here tbh.

Basically trying to figure out the best way of compositing passes together, im using HDR lighting and reflections so would I need to render out to EXR files?

Ive tried compositing regularly and cant get close LINK
Layers

thanks! any help appreciated

Last edited by UnionAdam : 04 April 2010 at 01:22 PM.
 
  04 April 2010
To get the most out of compositing, you'll need to carefully plan every render that will provide inputs to the process. You want every channel/layer of information to be produced separately. (Which the EXR format is capable of storing in just one file). Alpha channels should not be premultiplied.

Do not use lossy-compression. Do not use "image" formats (especially not JPG). Floating-point numbers, big sizes. Terabyte hard drives are dirt-cheap now. Splurge. Save every version of everything. Scrupulously keep a written log.

So the result of "all that rendering" at this point is not "an image." Rather, it's a bunch of masks and maps. Color maps, specularity, opacity (alpha), reflections, shadows, z-depth, surface normals, velocity (maybe). Every one of them clean and distinct.

"The image is then made in the digital Darkroom." Just like in the days of yore. Just like a mix-down in a recording studio. A network of nodes (a "noodle" in some circles) takes these inputs, and separately filters them and adjusts them and blends them, and uses one to modify another, and so on and on (the sky's the limit...) until ... voila! a finished picture appears. (Simple "layers" are not enough: your system undoubtedly supports both metaphors. Use "noodles," by any other name.)

And here's the sweet part: once all that laborious rendering is finished, it doesn't have to be repeated. You can adjust the node network and see the result in real time. If you find that a particular piece of it is hosed, you can selectively fix that piece. It looks daunting at first but there's no other way to do it.

Last edited by sundialsvc4 : 04 April 2010 at 06:39 PM.
 
  05 May 2010
There's a great DVD at the Gnomon Workshop for compositing elements together. Granted it uses Fusion, but the principals can be used in any compositing software.

It's definately worth buying!
 
  05 May 2010
Originally Posted by Sinew: There's a great DVD at the Gnomon Workshop for compositing elements together. Granted it uses Fusion, but the principals can be used in any compositing software.

It's definately worth buying!

I second that: Tim Jones makes an outstanding job covering the topic of using CG-passes for compositing, explaining in-depth important issues you won't find anywhere else.
 
  05 May 2010
sorry, this is a bit of a hijack, but as you were talking about the gnomon multi-pass compositing DVD I thought this would be a good place to get a little help.

I am following the DVD chapter on v-ray, I have all my passes in a .exr and have opened it in fusion, split up the passes into different nodes. Now this is where my problem arises. According to the DVD merging the Diffusefilter pass with the raw light/GI with a multiply should give me the same result as the normal light/GI pass right? They don't for me, the lighting is less or I'm losing some somewhere, I guess pictures will explain it better. The left image is my normal lighting pass, the second is my diffuse multiplied by my rawLighting. I have shown the same with the GI.

There are three lights in my scene, vrayspherelight as the moon, vrayplanelights at the windows, and a vrayplanelight in the fireplace (the orange light) There is also a FumeFX fire, I don't know if this is causing the problem but it shouldn't be.
 
  05 May 2010
Originally Posted by tozsam: sorry, this is a bit of a hijack, but as you were talking about the gnomon multi-pass compositing DVD I thought this would be a good place to get a little help.

I am following the DVD chapter on v-ray, I have all my passes in a .exr and have opened it in fusion, split up the passes into different nodes. Now this is where my problem arises. According to the DVD merging the Diffusefilter pass with the raw light/GI with a multiply should give me the same result as the normal light/GI pass right? They don't for me, the lighting is less or I'm losing some somewhere, I guess pictures will explain it better. The left image is my normal lighting pass, the second is my diffuse multiplied by my rawLighting. I have shown the same with the GI.

There are three lights in my scene, vrayspherelight as the moon, vrayplanelights at the windows, and a vrayplanelight in the fireplace (the orange light) There is also a FumeFX fire, I don't know if this is causing the problem but it shouldn't be.


I dont know FumeFX, but I would guess that the fire will be on a seperate pass, possibly the self illumination pass? If it is, just "add" it ontop of your current composition.
 
  05 May 2010
I'll check out the self illum pass, but I think FumeFX comes out as GI, that is why there is a lot of orange light in the GI pass (the leftmost picture). The fire itself comes up in the atmosphere pass, but there is no lighting there, just black and the fire, like matte material on everything.
 
  05 May 2010
Either self-ilum or it has its own pass. Anyway, check all passes.
 
  05 May 2010
no luck, I tried every pass available, none of them had any light information. Guess I will have to try switching off my FumeFX object to see if that is causing the problem
 
  05 May 2010
Originally Posted by tozsam: I'll check out the self illum pass, but I think FumeFX comes out as GI, that is why there is a lot of orange light in the GI pass (the leftmost picture). The fire itself comes up in the atmosphere pass, but there is no lighting there, just black and the fire, like matte material on everything.


how does it look if you "add" the atmospheric pass ontop on your composition?
 
  05 May 2010
Looks exactly the same, still has that missing light. I'm new to FumeFX and new to Fusion, so I might be doing something stupid, just can't figure out what it is. I'm pretty sure the light from the FumeFX fire is in the GI pass, otherwise there wouldn't be any orange in there at all
 
  05 May 2010
OK, at the mo I'm re-rendering without any light from the fire (hopefully) to see if that solves the prob.
Side question - which pass does my HDRI lighting? Is it contained in the GI pass?
 
  05 May 2010
You guys should check out the video below it helped me alot.

http://www.vfxvault.com/vfxvault.co...es_Chap_01.html
 
  05 May 2010
that tut was interesting, wish I had found that before shelling out at gnomon. The part about subtacting passes to find missing lighting info was particularly useful. Thanks amigo
 
  05 May 2010
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