rebuild final render from passes

[brizad13]

does anyone know if you can rebuild  an rgba final render from all the passes?
what order and blend mode needed for each layer?

[Rex]

According to DriesV you can rebuild a render using the following formula.

Composite = (Direct Lighting + Indirect Lighting + Caustics) x Diffuse + Reflection + Refraction
+ --> Linear Dodge (Add)
x --> Multiply

[brizad13]

rex,

i have been having some issues with re-building from passes. it seems some materials do not render correctly? can i send you a file to check into it?

[Rex]

Yes, please send the .ksp to rex@luxion.com via keyshot.wetransfer.com and I'll have a look at it.

[ghostweeble]

Hi! Did this ever get investigated? I'm having trouble figuring out how to rebuild from Keyshot 7's passes as well.

[Rex]

There was an issue with with the sample calculations of plastic materials that caused them to be more dull in the reflection pass. This will be fixed in the next 7.1 update.

Are you experiencing a specific problem ghostweeble?

[ghostweeble]

Hi Rex,

I'm just having issues parsing how to use the "formula" to recreate a final render. Is there a photoshop file example available anywhere that I could look at?

Thanks!

[Esben Oxholm]

I'm just having issues parsing how to use the "formula" to recreate a final render. Is there a photoshop file example available anywhere that I could look at?

I couldn't get something useful from it either. A Photoshop example file is a super good idea!

[ghostweeble]

Hi Rex,
Any chance we could get a sample .psd with correct layer modes and order for recreating a final render? Thanks!

[DriesV]

Here is a zip archive with a sample scene and PSD file.
I added the tori to have some reflective and refractive surfaces for caustics.

Please note that due to some discrepancies with Passes, it is possible that the composite does not match the original rendering exactly.
Also note that this technique of rebuilding the image from passes has limitations. It will not work for recreating "advanced" shaded results like translucency or metallic paint.

Dries

[ghostweeble]

Hi Dries,

Thanks for the file! (and I like the design of the ship!). It's strange to me that you don't even use the shadow pass in your composite. I also notice that the brightness between Keyshot and the photoshop (which very different), is closer if the brightness is raised to 2 in the Image tab of Keyshot. I wonder if there's something a little off in the way that Keyshot is exporting the passes? I don't expect Keyshot renders to be pixel for pixel matches with a composite image, but I would have thought that they would be much closer than this?

I didn't realize that I had to subscribe to this post to be notified but now that I have I'll reply much sooner!

Thanks!

[ghostweeble]

Hi all,

Any thoughts on my above questions? I'm  wondering especially why the brightness is so different?

Thanks,

mm

[DriesV]

Hi ghostweeble,

Yes, there can be some discrepancies between the composite and the KeyShot beauty image.
We are addressing a bunch of these in the upcoming 7.2 update.

I didn't use the Shadow pass, as shadows are included in the Lighting pass as well. The Shadow pass is meant to accentuate shadows.

Dries

[ghostweeble]

Thank DriesV,

One thing I noticed that's been updated in Keyshot 7, is that when I import a polypainted model via the bridge from Zbrush, I get a Texture(legacy) node. If I click the 'Upgrade to New Node' button, I now get the ability to turn off the MatCap, and the vertex color is correct between the apps! Previously, to get rid of the MatCap, I had to switch to Vertex Color, then insert a color adjust node to gamma correct the polypaint/vertex color.

This is great! I'm wondering why Keyshot defaults to using this legacy texture node rather than defaulting on the new node?

Honestly, I wish there was a way to make the MatCap turned off as the default. It's really not useful in Keyshot at all.

Thanks,

mm

[Rex]

We are currently working on utilizing the new texture mapping technique on imported textures.