Add Deep EXR data in Cycles

I believe Blender Cycles is currently missing a crucial feature: Deep EXR support ( openexr.com/en/latest/TheoryDeepPixels.html ). Here's why it's absolutely essential:

First, it has become an industry standard.

It allows more efficient scene splitting, which helps manage computational resources better.

It enables advanced compositing workflows, combining 2D elements and complex 3D effects (like smoke, particles, etc.) seamlessly, all without needing high-end hardware.

Blackmagic Design added it to Fusion after strong community demand, just like they did with USD support.

The lack of Deep EXR in Cycles prevents studio adoption, since most production pipelines now rely on it.

One major issue: Cycles doesn't store depth properly on volume objects. That’s a big limitation in high-end workflows.

Yes, Deep EXR files can be heavy, but the integration isn’t as complex as it seems. I personally requested this feature from Guerilla Render, and their dev team implemented it in just two weeks, with a single developer.

It’s not just a “nice to have,” it’s becoming mandatory for serious VFX work. Even Embergen is adding Deep EXR in version 2.0, because it's been heavily requested for FX pipelines while still using their own volume renderer.

I prefer rendering VDBs in Blender, but I also use Embergen when needed. Still, I'd love to keep everything inside Blender which would be possible with Deep EXR.

So please, Blender devs, bring Deep EXR to Cycles. It's long overdue. I’m currently working at a studio that doesn’t use deep data, and we constantly hit limitations in compositing. Holdouts in particular are a nightmare. I showed the team what’s possible with Deep EXR, and now some parts of our episodes will use it to speed up post-production.

For reference: I tried faking it with Z-Front in Fusion, but it’s far from perfect, especially with transparency and motion blur. Also, Blender's Z-pass doesn’t translate well when generating deep data in Fusion, I had to reverse it in odd ways to make it somewhat usable.

Thanks for your attention and fingers crossed we’ll see Deep EXR support in Cycles soon !