Hello,
Here is what we would like to achieve ultimately :
produce a webm (VP8) file of a Niagara system with all of its glorious transparency and bloom that we can see from the viewport in Unreal(v 4.27.2).
We’ve explored a lot of possibilities with no satisfying result yet :
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rendering a sequence of EXRs through the movie render queue
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using OCIO to render in the ACEScg color space (which disables the ToneCurve)
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using the linear SRGB workflow (manually disabling the ToneCurve via the Color Output setting)
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using a combination of green, blue and red screen method which probably produced the ‘best’ end result but was still far from what we see in the viewport and felt like a workaround rather than a real solution
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rendering a PNG sequence (we were desperate
)
We’ve tried with both the ‘allow through ToneMapper’ and ‘Linear color space only’ options in the project settings (Enable alpha channel support in post processing)
What we found out was :
We cannot find a way to get a clean alpha which includes bloom.
The bloom is present in the RGB channels but not in the alpha channel which is why the ‘Green screen’ method worked out best. We just bypassed the need of an alpha channel by ‘keying out’ the unwanted background.
We tried rendering without bloom but our ending result had washed-out colors (very pale, if not almost completely white)
We feel like we’re doing something wrong with the render options and possibly the Color Management side of things, although it seemed pretty straightforward watching these videos :
Here are a few examples using the ACEScg workflow:
Picture 1 is the RGB only (what we should get but this is without the transparency)
Picture 2 is the alpha channel only (as you can see, no bloom is visible here)
Picture 3 is the RGBA (we even lose color in the process)
Is it even possible to have the bloom in the alpha channel ?
Is it possible to render a webm that is a true representation of what we see in the Unreal viewport ?
Picture 1
Picture 2
Picture 3
