Vray Render passes

[Rhys]

HI all

I know this has been a quite heavily covered topic. And yes i've read through Chris' post on getting this to work in nuke.

I'm using after effects to set the comp up.

Specular -add
Refraction -add
Reflection -add
Global Illumination -add
Raw Lighting - multiply
Difuse Filter -BASE

The problem i have is when i multiply the raw lighting i get an edge around the objects.
This is not an alpha problem.

I was trying to build a more complex compistion up with adding in the shadow pass. Does anyone have a tried and tested method for getting this to work.

Thanks

[Rhys]

Also having a look at the render, is there any reported problem with vray proxys and render elements?

[shkumbin]

did u make sure u have the "enable filtering" option checked on the render element rollout for rawlighting?

[Seraph135]

The problem i have is when i multiply the raw lighting i get an edge around the objects.
This is not an alpha problem.

I was trying to build a more complex compistion up with adding in the shadow pass. Does anyone have a tried and tested method for getting this to work.

Thanks

It may still be an alpha problem. Anytime your going to be multiplying pre-multiplied passes together you need to first remove the pre-mult, then multiply the passes together, then pre-mult them again.

Tim J

[sv]

Further to Tim's suggestion you could try this:
(As Tim helped me with this some time ago and it works beautifully well - no halos at all - thanks tim )
Basically generate the RAW lighting element yourself.

Use these elements:
Lighting
Diffuse
GI
Reflections
Refractions
Spec

then either put them in an exr (AFX won't be able to read that though I don't think, at least not natively with these current versions) or split out the elements into there own renders, then:


Again this is nuke, not AFX. And it needs to be linear float....

[Rhys]

ok thanks for that. I'll try putting it together in nuke. at the moment we are trying to decide weather to go for nuke or fusion. i know both have there pros and cons. have both installed with trail versions. Anyone know any major reason to choose one other the other?

Also if i wanted to control the shadows more in post, how would i then add that to the chain ?

[shkumbin]

I use multiply mode for shadows, then play with levels to adjust intensity etc.

[Rhys]

but where are you connecting them to ?

Also good news put it all together in nuke and works perfectly!

one thing that didnt work which is probably down to my limited nuke skills. is that i didnt render out a background pass. so wanted to take the background from the rgba channel and then use the alpha mask, but by doing think i get a look of it being premultiped and when i do a difference over original and comp have a white outline. how can i get rid of this.

also if i was to have the background channel how would i put that into the flow?

Thanks

[Seraph135]

but where are you connecting them to ?

Also good news put it all together in nuke and works perfectly!

one thing that didnt work which is probably down to my limited nuke skills. is that i didnt render out a background pass. so wanted to take the background from the rgba channel and then use the alpha mask, but by doing think i get a look of it being premultiped and when i do a difference over original and comp have a white outline. how can i get rid of this.

also if i was to have the background channel how would i put that into the flow?

Thanks

Shadows should be "multiplied" OR just a simple "over" the lighting (or raw lighting) pass.

The background could be difficult. You might not be able to get rid of the edge very easily. I think at best you'll be able to re-create the beauty pass from all your passes, but as soon as you start making adjustments to the separate passes you will start getting edge problems.

The best thing to do would be to re-render everything correctly on black backgrounds and have the background pass separate. If you had the background pass you could just merge the result of all your foreground elements over the background element.

Tim J

[Rhys]

Thanks Tim

Looking forward to your new dvd coming out on Multi-Pass Compositing. How advanced do you go in this compared to the above?

[Seraph135]

Thanks Tim

Looking forward to your new dvd coming out on Multi-Pass Compositing. How advanced do you go in this compared to the above?

The dvd starts off with some basic pass rendering and compositing using scanline and render elements. I say "basic" but I don't really consider the info discussed there to be all that simple. It seems like simple stuff, but it gets your brain focused on rendering the right elements in the correct way. Which is important later on when your dealing with more complex passes and situations. From there I go into topics like lighting passes, bit depth, ambient occlusion, etc. In those sections I show a lot of examples. I explain what they are and how they work, but more importantly I show examples of where they work and where they don't and explain why. Some of the info shown in this thread is in there, but the DVD goes further into rendering and compositing passes from Vray. There is also a section which breaks down the comp used to create the artwork on the DVD cover which was also rendered in Vray. The main goal of the DVD was not to just show how "this" or "that" pass works and what blend modes to use (although that is in there too). I really tried to show as many examples as possible of problems I've seen come up in production, explain why they happened, and show how to fix them. I also really wanted to explain and show how all the math works inside your 3d package so that you know when compositing how to mimic it exactly. This opens up tons of room for creating really high quality composites without degrading the image quality through incorrectly applied color corrections which can break the realistic behavior of the lighting in the scene.

Tim J

[sv]

WOW can't wait for this.
When can we expect it Tim?

[jacksc02]

the DVD sounds good Tim.
What comp package will you be using in the DVD?

[Seraph135]

When can we expect it Tim?

Sometime this month. I don't have an exact date yet.

What comp package will you be using in the DVD?

I used Digital Fusion, but the information should transfer to any comp package.

Tim J

[shadevfx]

Does anyone have the proper ordering to do this using the raw passes?

I thought I had it worked out, but it's coming out a little washed out.

thanks!

B