Vray 3.08 - matte issues

[Deflaminis]

Hello, I think I may have the wrong workflow, because I can't get reflection and shadow mattes to work at the same time.

If I check Matte object, I get shadows and they look right. If I check refl matte I get reflections and they look fine. But if I click both, I get nothing. Is this expected?

If so, is there a workflow that works best in this case? I just wanted to catch the reflections and shadows at the same time, nothing too fancy. Using max and 3.08

[Deflaminis]

Edit: Thought I had it, but I was wrong. My alpha doesn't seem to carry the reflections out of max. Example below:



Where did the reflection go? It seems to be there when I'm rendering and saving out, but when I comp it's very faint. (It IS there, but you can't really see it. Same in Photoshop or After Effects.) I'm not sure where I'm going wrong, but obviously I've missed a step or something...

Since it's a matte it doesn't show in the reflection pass... hmmm.

[vlado]

Hm, seems to work fine for me, can you post that part of the scene?

Best regards,
Vlado

[Deflaminis]

Certainly, I'm sure I've left out a checkbox or something. Thank you for taking a look. I really appreciate your time.

I've scaled down the textures to reduce overhead, but the file is the same setup. I was saving out .exr's, if that's relevant. Replaced the cup geo with something simpler.

[svetlozar.draganov]

The reflections are probably there but their contribution is too low because their alpha value is about 0.3.
How did you compose the elements? What elements are you using and with what blending operations?

[Deflaminis]

I'm just rendering the matte and putting it over top of the backplate in post on a regular "normal" layer. Nothing fancy. Maybe I need to unpremultiply? Maybe my post tools are just too, too bad for the job.... Adobe...

You'd think that if the alpha was too low that the shadows would also be affected by that, but the shadows seem ok there, just missing the reflections. Is it possible that the shadows have one alpha/gamma level and the reflections have another? If so, how do I fix this? I may not fully understand the reflections mattes, but the material that's catching the reflection is setup to match the marble countertop with fresnel reflections, so it wouldn't even really be 100% pure, though .3 seems a bit low based on the original render. When it's not a matte, it produces strong fresnel reflections similar to the max render and original countertop. I'm only using 1 hdri light on this, emits diffuse, spec, and reflections.

What should I do in 3dsmax or post to boost the reflection alphas without darkening the shadows?

Thanks for the help figuring this out.

[svetlozar.draganov]

You are placing RGB-pass from V-Ray over the BG-image in Photoshop using its alpha channels as mask - is that what you are doing?
Can you also send us the Photoshop file for investigation?

[Deflaminis]

That is correct... I've used Nuke before but I don't own it. (I wish...)

I saved out .exr's from max at gamma 1.0. One thing to note is gamma values in photoshop are quirky when it comes to alpha channels and linear workflow from my experience. To keep things clear, In Photoshop I'm using a gray working space of gamma 1.0 (custom), and my color management profile is set to "convert to working gray". The default exr opener uses an alpha gamma of 1.8, which generally you have to manually disable. (From what I've seen.) This definitely applies to EXR's. I'm on Adobe CC.

In after effects, I'm using a 32bit comp with color settings set to 32bit per channel (float), Linearize working space. I have included the AE file in the zip here as well. The alpha does look a bit better in AE than in PS, though it's not 100%. (And, seems to desaturate the alpha.)

I know that Adobe for compositing is generally a bit behind the times, so If it's Adobe that's the issue that's fine and I'll find another way. Just want to be sure I'm not doing something way wrong in here.

Neither supports color in the alpha channel... maybe related? I wonder if the problem is just exr's in photoshop, will try with hdr tomorrow if I can get a chance.

The file is too big to put on the forums, here's a link to a zip file and thank you very much for your time.
http://www.diffus3d.com/Outbox/Mattes_Vray_308.zip

Best Regards,
AJ

[svetlozar.draganov]

Here how the composition looks like in Nuke:


Both images are blended with Over operation(A+B(1-a)). As you can see the reflections are there.
Their contribution is a bit lower than the result from Max but the result is definitely better than the one you got in Photoshop.

As far as I know Adobe products are not the best ones when it comes to operate with 32-bit file formats and I can't tell you why it doesn't work in Photoshop or how to set up it correctly. One thing you might consider is to increase the alpha values for the reflections manually in Photoshop or to make the Vray Materials of the matte-surface more reflective.

[Deflaminis]

It's a fair answer, thank you for looking into it. It's not hard to work around, I guess sometimes I just want to be sure I'm not doing things incorrectly. As long as my setup isn't outlandishly wrong I'm satisfied. I really appreciate your time.

Best Regards,
AJ

[SimonC]

I am having the same issue also. Can you say what you did to get it to work?

Attached is a simple text scene using 2 vraymtlwrapper materials having the the same base reflective material.
I can get reflections or shadows but not both.
Also if I set the reflection glossiness in the base material to 1.0 then the reflection doesn't appear in the render at all!
Using Max 2014 SP3 (16.5.277.0) and Vray 3.07.

Matte-Test.zip

Regards
Simon.

[svetlozar.draganov]

This is what I got from your scene with version 3.00.08 without changing anything but the output path:
RGB:

Alpha:

And this is the result when I compose that RBG-pass with another image (RGB=255,0,0) using over-operator.


Both reflections and shadows are there.

Can you show us how the things looks like in your environment and what compositing software are you using?

[SimonC]

Thanks for the prompt reply.
I have since upgraded to 3.00.08 and it now renders correctly.

This is what I was getting with vray 3.00.07

and


Thanks for the help.

Simon.

[tashko.zashev]

Thanks for the prompt reply.
I have since upgraded to 3.00.08 and it now renders correctly.

This is what I was getting with vray 3.00.07
[ATTACH=CONFIG]21424[/ATTACH]
and
[ATTACH=CONFIG]21425[/ATTACH]

Thanks for the help.

Simon.

Glad to hear that. The latest service pack ( 3.00.08 ) has some fixes related to the matte functionality.