Composite back to beauty issue

[KushKush]

I have rendered scene together with render elements based on Vray next documentation "render elements/rgb color" (basic method back to beauty)
When I load exr in photoshop and compare all render elements(Linear dodge Add) to RGB I have slight diffrences. Why is that? Anyone has a helpful tutorial compositing in photoshop Vray next render elements? is there a method to figure out what I'm missing?
Thanks ahead.

[hermit.crab]

Best you send the scene to support@chaosgroup.com so we can take a look. Mention this forum thread in the e-mail along with your V-Ray and 3ds max versions.

[KushKush]

I'll do,thanks.

[hermit.crab]

Thanks for the provided scene. Here are the things you need to do to get a correct composition:

1. Install the latest stable V-Ray NEXT build - There are some issues regarding compositing that were fixed
2. Add a VRaySSS2 pass to your composition - You've skipped this element
3. Some of the differences are a result of the duplication of refractions and reflections because of the materials' affect channel "Affect All" options. To avoid duplication, set the following materials' refraction and reflection channel affection to "Color only": 'WALL', 'Material #99' (in the curtains), 'Fabric01' (lamp).

[KushKush]

Thanks for taking time looking into issue.

1. I currently use vray next 3.1, isn't that latest build?
2. I do have SSS2(pics above), I've probably did not include in the scene file I've sent.
3. If I switch 'Material #99' Curtains 'Refraction' from All channels to Color only then how am I suppose to get curtains correct alpha? For example placing background image in Photoshop.

What is the correct way to set render elements in Photoshop? "VraySelfIllumination down to VrayGlobalIllumination On "ADD" blending mode? and VrayLighting render element on "Normal" blending mode?

[hermit.crab]

1. I was referring to the stable nightly builds.
2. Yes.
3. Here it gets a bit troublesome. There are some known issues when compositing refractive materials (internal bug-tracker id: VMAYA-8854) so to get a correct composition and save the "affect all" options you should do the following:
-Change the materials' 'WALL' reflection to 'Color only' and 'DiningGlass' refraction to 'All channels'
-Because of the mentioned issue, there will be a double refraction on the curtains, which you can clean by masking the VRayRefractions
-The correct compositing method in Photoshop is all beauty passes on "Linear Dodge (Add)" blending mode, except the bottom one which is Normal.

[sebbiej]

I'm having an ongoing issue whereby if I try to compile my elements back together in photoshop (using an add operation), the renders are always super bright and contrasty, and bear no relation to what I'm seeing in the frame buffer.

My setup is to have the Mode as Color mapping only, no gamma.
Rendering out 16bit (half float) EXRs.
Photoshop doc is a 32bit document with the Color settings set up with Gamma of 1 in the working space, and Blend RGB Colors Using Gamma: 1.00

My renders look fine in after effects but I can never get them to look exactly like the frame buffer in Photoshop, and can find no explanation why... If I drag and drop the beauty/main element in to the same Photoshop doc, I need to add an exposure layer with the gamma set to .454 and then that'll look ok, though.

[hermit.crab]

sebbiej Seems like double gamma is applied. What kind of a profile (Edit>Assigned Profile) do you have set?

Gamma of 1 in the working space

Where have you set this?

[sebbiej]

sebbiej Seems like double gamma is applied. What kind of a profile (Edit>Assigned Profile) do you have set?


Where have you set this?

It'll look really overexposed if I use the sRGB IEC6196-2.1 Color Profile on a new 32 bit doc. I've also tried setting a custom profile via Edit > Color Sittings > Working Spaces > RGB: Custom RGB then setting the Gamma to 1:00 in there, but the renders/elements still look exposed when adding them together in the PSD. Thank you for the help, it's a bit confusing! I usually comp up renders for animation in After Effects, but the Photoshop setup is puzzling me a bit.

[hermit.crab]

You mentioned earlier that your .exrs are 16-bit. Does it work on 16-bit mode? Try using the "Convert to Profile" option to set your Color Profile and switch to 32-bit again. Also, what's the point of linearizing the Color Profile? That would require you to apply a gamma manually in a similar fashion. On my end, the sRGB IEC6196-2.1 profile produces similar to the VFB results.

[sebbiej]

You mentioned earlier that your .exrs are 16-bit. Does it work on 16-bit mode? Try using the "Convert to Profile" option to set your Color Profile and switch to 32-bit again. Also, what's the point of linearizing the Color Profile? That would require you to apply a gamma manually in a similar fashion. On my end, the sRGB IEC6196-2.1 profile produces similar to the VFB results.

I think I've figured out where I'm going wrong (or where my Photoshop setup is going wrong). It seems that the stacked, added elements go overly bright if I make a new 32 or 15bit doc and drag the EXRs into it. But, if I open the main beauty EXR straight into Photoshop and then bring in the other passes on top of that, adding up all of the elements seems to work pretty much correctly. Confusing to say the least.

I was trying to linearise the color profile as I got a bit lost reading up on the setup along the way, I think someone recommended that setup on another forum.