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objuan
09-24-2015, 04:15 AM
I'm trying to composite some soft edged particles on top of my animation. The particles loop and do the same thing, while various other elements change, including a lighting shift from day to night and back.

My particles look good, until they get put on top of a different bg then they started out on, then they get a kind of light halo aura that is not what I am going for. I imagine it is because they have the original bg baked into their transparency (I set all my objects to render Constant Black, which is good so they mask the partis when they go behind stuff)

What is the best way to render/composite soft particles so they are multi-versatile come comp time?

Builtdown
09-24-2015, 04:53 AM
Maybe render the particles in very high resolution, so the halo might get smaller?

But I think best way would be using the various bg layers as image sequences and rendering the particles on them.





I'm trying to composite some soft edged particles on top of my animation. The particles loop and do the same thing, while various other elements change, including a lighting shift from day to night and back.

My particles look good, until they get put on top of a different bg then they started out on, then they get a kind of light halo aura that is not what I am going for. I imagine it is because they have the original bg baked into their transparency (I set all my objects to render Constant Black, which is good so they mask the partis when they go behind stuff)

What is the best way to render/composite soft particles so they are multi-versatile come comp time?

ernpchan
09-24-2015, 08:41 AM
Are you premultiplying your footage or using the alpha as straight? Doing one or the other usually fixes it.

objuan
09-24-2015, 10:21 AM
I have tried both Straight and Premultiplied in AE, and neither looks that great on the dark bg. Is there something I should be doing at render time in LW to prep for Premultiplication?


I was sort of able to 'fix' it in this case by Tinting my layers in AE, but that only works cause my parti's are pretty much the same color. I would prefer a more robust solution...

jeric_synergy
09-24-2015, 10:35 AM
For a complete answer, post straightn & prem. render sample frames here and let forum users play with them.

prometheus
09-24-2015, 12:42 PM
hard to tell, would need samples posted, as well as feedback on what type of particle render you got, hv sprites?surfaces, volume, partigons?
and also what type of image you are rendering out to...and perhaps what type of keying out..if you do that with effects etc in after effects.

I would render out as tga 32 with alpha.

jeric_synergy
09-24-2015, 01:04 PM
TGA? Hey, grampa, come into the 21st Century. PNG32 w/zero (lossy) compression.

objuan
09-24-2015, 01:13 PM
Samples attached.
129879

Not that I am endorsing Jeric's use of the word "grandpa" but I did render everything as png32 image sequences, and in AE all layers are Normal blending at 100%. I was thinking a different blending mode might work better, but none of them really did what I want. Seeing as how I rendered the orange and purple separately (they go one at a time later) I imagine if I matted all my object to orange and set the bg to orange and rendered it would give me the results I want.

But I want a solution when it comes time for a rainbow sparkle unicorn dust freakout...

jeric_synergy
09-24-2015, 02:16 PM
#aflw and production machines:

Objuan, have you yet tried the blending mode(?) "Luminescent Premultiplied"? IIRC, that's LW's default RGB/Alpha rendering technique. On the rare occasion where I'm compositing, using that mode has solved most halo-ing issues. It's buried at the bottom of the AE Layer blending mode dropdown. It's not the same as the choices in the Footage Interpretation dialog.

I don't even know if one can change LW alpha rendering to "Straight".

raw-m
09-24-2015, 03:50 PM
Similar to ernpchan's comment, i get the best results rendering out of LW with a straight/unpremultiplied alpha and then making sure the alpha is set to Straight in AE, 32png works well for me. You need to match LW alpha settings in AE.

jeric_synergy
09-24-2015, 04:16 PM
I don't even know if one can change LW alpha rendering to "Straight".
The alpha options include color space (4 options) and Premultiply Alpha and UNmultiply Alpha, which gives you a dialog box saying "No Backgrounds Allowed".

Is "Unmultiply" the same as 'straight'?

raw-m
09-24-2015, 04:19 PM
Sorry, wrong terminology on the LW side, it's not in front of me, but yes.

jeric_synergy
09-24-2015, 04:32 PM
Sorry, wrong terminology on the LW side, it's not in front of me, but yes.
No worries: that was more just a note to myself.
+++++++++
Objuan, can you please post a PNG32 render of just the particles, rendered with Premultiply? I'd like to play around in AE with that.

one with light, one with dark bgnd rendered would be even better, as it would illustrate any haloing better.

objuan
09-24-2015, 06:13 PM
129938
129939

I'm afraid with the juggling of too many projects I dont currently have the time to play with these in AE, but from the looks of it, the Unpremultiply is just what I had in mind.

Thanks! (I'm pretty sure)

jeric_synergy
09-24-2015, 06:28 PM
This was rendered with UNmultiply in LW? Pity, I was hoping to test the default Premultiply mode in AE to see if the fabled Premultiply Luminscent mode did the job proper.

objuan
09-24-2015, 06:51 PM
the 1444 (original) is standard LW Premultipy.

Can you tell I'm trying to avoid the stuff I should be working on?

jeric_synergy
09-24-2015, 07:00 PM
OH, there's 2 images there-- sorry, it looked like one here....testing now....(man, thought I was losing my marbles....)
++++++++++++++++++++++++
OK, there's 2x2 cases here: INTERPRETATION= straight or premultipied, and BLENDING MODE=Normal or Preluminscent Multiply: this should make it clear that, IMO, Pre&Pre are the way to go.

129940
(be sure to view this image full size, not in whatever your browser sizes it to.)

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