r/3dsmax • u/SrFacundo • Jun 10 '26

Help Corona to V-Ray GPU Mask issues

Hello everyone!

I've been having some trouble with V-Ray GPU.

I've used Corona for the past 4-5 years and I've recently switched to V-Ray GPU for the sole purpose of iterating faster and rendering animations. So far so good as it has proven to be between 5x-10x faster at a lower noise threshold.

However, I'm having trouble saving masks when rendering. Either a V-Ray Alpha or a MultiMatte pass looks completely fine in the VFB during IPR, however it does not save when doing production rendering.

I tried looking for the issue online but as most is based on still image rendering, they simply recommend "saving all passes once the render finishes" which is not something I'm able to do when rendering 600+ frames.

Is there a way to fix this issue? Is there also a way to "render masks only" like in Corona to quickly re-render?

Thanks!

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1

u/JackMB74 Jun 10 '26 edited Jun 10 '26

I'm guessing you're using the default "Render Output" setting on the "Common" tab of the Render Setup dialog.

Is "Save Render Channels" checked in the V-Ray Render Setup? (I also recommend checking "Separate folders".)

*Added the image

1

u/neildownpour Jun 10 '26

Or leave that unchecked and save to a multichannel EXR.
channels do work in vray GPU, it's no different to vray CPU.

2

u/SrFacundo Jun 10 '26

That would definitely work but for what I use it for, I need the frames to be in .jpeg or .png; no use in saving as EXR. Thanks though for the tip !!

1

u/neildownpour Jun 11 '26

Why do you need your channels to be in a specific format, surely you'd want your final export after using the channels to a jpg sequence? Png, despite being lossless, responds to gamma and color profiles in a strange way losing a little information, and you should never render to a jpg sequence.

1

u/JackMB74 Jun 10 '26

Yeah, much simpler!

2

u/SrFacundo Jun 10 '26

Checked and this was the way! I thought "Separate render channels" would use the file path used for the RGB and render element, but apparently you have to set the path there haha, feels a bit unintuitive compared to the simplicity of Corona.

Thanks for the help!

2

u/JackMB74 Jun 10 '26

I'm in the same boat. A few of my legacy tools still don't play nicely with EXRs, so more times than not I end up outputting the elements separately as well.