Today, I’m Very Exited to share with you guys one of my best workflows that can literally save you hours of work, maybe days of work.
Partly because of the massive control that it gives you over pretty much everything in your 3d projects, from the amount of reflection, refraction, global illumination, lighting, SSS, shadows and much more! It’s incredible!
I will show you exactly how you can apply This modern technique to your pipeline to make your workflow more efficient, Economical yet make Quick changes to your projects in no time in a very artist-friendly way.
MultiPass Compositing for 3D Visualization
In case you are wondering, multi-pass compositing is a technique that allows you to combine different V-Ray passes in order to pixel match the Beauty pass result that comes out, out of V-ray, and then you start your color correction and fixes process from there.
Keep in mind that all of this happens before you hit the render button, and the more time you spend on this stage— the more clean and efficient it will be later on in compositing.
Another key point, everything has to be linear for a correct math, otherwise, we will get broken Composite that doesn’t much it all the beauty pass. “Got you Covered on that → watch this practical video, that explains step by step the Gamma setup in 3ds max and vray.
Here’s the project that I’m going to be using for this case study, and I made some mistakes on purpose so that we can fix them together ( you get the project files to practice).
Your Link To Download Project Files
1 .V-ray Render Elements
First thing you can do is go to Render Elements Tab and Choose the Following Passes,
What we have created now, is the necessary passes needed to create and match our beauty pass result in vray, and here’s the result of the above passes, It’s time to hit that Render button.
One Tip, use EXR as it allows you to get one file with multiple passes, or you can make use of the Separate Render Channel, as you like both works fine as long as it’s 16 bits or 32bits.
2. Combining the Passes in Photoshop
I Normally use Nuke for Compositing, But the some approach can be applied to any software you feel comfortable working with ( In this quick Case study I’ll show you how to combine passes in nuke and Photoshop ).
There is one rule when it comes to this step, the passes that we used, in this case, are not raw, they are already multiplied by the vray filter, so to create a mathematically correct composite we will use a simple addition blending operation for all the passes, that simple.
And since this is math,
1+3+2 = 2+1+3 = 6
What I wanted to demonstrate with the math above is that there is no rule for which pass come first, as long as you make an additive blending operation, everything will work just perfect.
Now here is the process in Photoshop,
|VRayGlobalIllumination||( Change Blending to, Linear Dodge Add ).|
|VRayLighting||( Change Blending to, Linear Dodge Add ).|
|VRayReflection||( Change Blending to, Linear Dodge Add ).|
|VRaySpecular||( Change Blending to, Linear Dodge Add ).|
|VRayRefraction||( Change Blending to, Lighter Color. Or Linear Dodge Add ).|
Result is A Complete match:
Tip a : We used Lighter Color for refraction, but you can use the Linear Dodge Add as well, both are Addition Operations, as from my experience sometimes refraction is added to the reflection “weird, but true!” so when you add refraction, use first Linear Dodge Add and if it doesn’t match use Lighter Color.
Tip b: The Base of your Photoshop composite, you can leave it as it is, Or change it to Add, it will be the same result as we are adding to it.
Tip c : In case you are wondering the Specular here is not the old fake reflection from the 90s, this is the reflection of the light sources in top of the reflected objects in the scene.
Now just for Fun try to switch the order! it will remain the some as it’s all correct math! Except for the Refraction as it has to be at the end of the chain ” Remember, We used another kind of addition operation for Refraction”.
Adjustments and Corrections “Pure Awesomeness”!
Next step is to start playing with the passes and see if there is issues you want to get rid of.
here is my lists of Quick fixes and Adjustments,
I went in and started working on the Reflection pass since all the fixes are related to reflection, but later I made other adjustments on other passes as well.
- Using a Brush and masks.
- Using the Exposure Adjustment layer as a Clipping mask.
- Make use of all the available passes.
Voila! Result of the above fixes
Supported Feature in Photoshop 32bits Canvas
Let’s have a look at the supported Features and tools in Photoshop while working in a 32 bits float Canvas:
2. Combining the Passes in Nuke
Compositing the passes in Nuke is much easier, faster and artist friendly, quite easy.
I’m going to work with the EXR version this time, and extract the passes one by one.
a. Extracting the passes
EXR is a file format and a Container that store the passes, to extract those passes you need to work with the Shuffle node.
b. Merging and Blending The passes
Once you Shuffle all the passes, it’s time merge them together and for this, use the Merge node and change the Operation ( Just another name for Blending mode in Photoshop ) to Plus.
Except for the Refraction pass to atop.
|VRayGlobalIllumination||( Change Operation to, Plus )|
|VRayLighting||( Change Operation to, Plus )|
|VRayReflection||( Change Operation to, Plus )|
|VRaySpecular||( Change Operation to, Plus )|
|VRayRefraction||( Change Operation to Plus. Or, atop )
c. Adjustments and Corrections
In this stage, like what we have done in Photoshop earlier, we can start using the color correction node in nuke.
I’m going to use the Grade node to add more lighting by changing the Multiply value from the node option:
That is it, we are done.
Hope you find this case study helpful.
All the best,
USEFUL LINKS AND RESOURCES
- [ Video ] Multipass Compositing in Photoshop – Vray Render Elements.
- [ Video ] Gamma 2.2 Setup In 3ds Max and Vray Practical Video Tutorial that shows you how to work with correct math inside 3ds max and V-Ray in order to get realistic 3d renderings.
- [ Video ] Multipass Compositing in Nuke – Vray Render Elements
- Understanding Linear Workflow If you want to know more about why this workflow.
- Features that support 32‑bpc HDR images in Photoshop supported tools you can use while working on your passes.
- Photoshop Blend Modes Explained Great and detailed Article by Robert Thomas about Blend Modes in Photoshop.
- ProEXR. Extracting passes with this tool is a piece of cake.