Render Help: Glow on atmospheric effect

[amckay]

Well just to let you know, worst case scenario render it out and apply glow to the lumience of the pass within video post or in another compositing package.

[Dave Black]

FWIW, you can also apply a sort of bloom/glow effect using the blur render effect. You can base it on lumience from there, and, do it by object id, or effects id. Itwould take a bit of tweaking, but it could work as well.

Allan's way will cause you less of a headache, though.

-3DZ

:D

[FatAssasin]

Yeah, I usually use Blur instead of Glow because I like the control you have over the glow. But that doesn't work with the fire effect either. I seems like effects just don't work with atmospheric render effects.

It looks like I will have to render it out straight and then apply the glow afterwards. Thanks for the ideas.

Along the same lines, how would I go about comuting the alpha channel from an object without rendering the object itself? I'm trying to add this engine blast effect to some spaceships I've already rendered, so I would want the alpha channel for the render of the blast effect to include the blast, but not include the parts of the ship that cover it. Could I do something with the Matte material to "hide" the ship but not the alpha channel?

[Dave Black]

That's what i'd do. Might have to play with the matte/shadow material settings to get the alpha right, but that should work.

I find it rediculous that we can't find a way to apply glow within max. Hmmm. Oh well. If you figure it out, let us know!

-3DZ

:D

[FatAssasin]

Yeah, you'd think "fire" and "glow" would go hand in hand.

[Aldaryn]

I think a solution to the problem may be using glow based on unclamped colors.
Well, if you have a fire effect, it can also render out with unclamped values, and thus, you can base glow calculation on it.

Of course this requires the fire effect to be over a certain value... Best to go over 1.0, and blurr the edges of the glow, for it to apply over the whole fire effect thing...
And if you are compositing this effect over another render, you could just apply a glow to all non-black pixels of the image, since the rest of the image is black.

By the way, I've tried out the glow on atmospherics, and it works for me.
Both in max scanline, and in Brazil.

[FatAssasin]

Okay, that's exactly what I'm trying to find out. What settings did you use to get it to work for you. I don't need a work around if there's a way to get it to do what it's supposed to.

[Aldaryn]

I never use blurr as a "glow" effect, maybe when I want to create something like a sleepy feeling thingee... Heck... well...

So the setting: standard Max render effect: glow, based on pixel luminance information, on unclamped color values. (This way max will preserve the unclamped colors (as well as the clamped output)) The "fire effect" can be any type of atmospherics. This matters nothing. But my fire effect has a "super white" center, with pixel color values going over 1.0 Like a chrome specular or something. (The edges of the effect remain still under 1.0 luminance. ) After the render in the post fx pass the fx renderer will select pixels with a color value over 1.0 so the pixels in the center of my fire will be selected.

IMHO, Using unclamped color based glow can be the best choice to apply image pixels based effects, such as "glow". Using a careful setting (nusually pixels with values above 1.0, or 1.2) will produce a realistic camera like effect, because the pixel selection was based on "realism". Of course this requires a "realistic" scene setup with material properties in sensible relation wit each other (specular, mostly...) . But this can save time. No need to set up effects bny object and object.

Hope you can creat what you desire. :)

[Aldaryn]

I've created a few fire fx lately, and I've come across this problem:
Some atmospherics refuse to cooperate with unclamped clors. A default max farmebuffer won't hold the color information of specific atmospherics. This is sad... :(
A way to fix this, is to use another renderer, both FinalRender and Brazil will hold pixel info. of atmos. :)
And there is another fast, yet simple way to deal with this problem, without 3rd party renderers:

I've created this image just 2secs. ago. A standard max fire with 3 blue spheres.
http://www.revai.hu/~mcdodee/upload/fire_fx.jpg

As you can see, only the fire effect is affected by the glow.
This result can be done by using a glow on the wloe image ("Whole") and setting a pixel selection filter to "Bright"
This is similar to unclamped selection, but it works well with clamped 8bit color ranges. You can set the Bright value between 0-255. In the image above it was set to 244, so pixels with a color value average above 244 will be glowed.
The spheres won't recieve any glow, because even their specular is dimmer than pure 255 white.

I think this solution works. But the lack of unclampedness still remains really annoying.

If you have afterburn, use it, you won't find any trouble creating a glow with that. :)

[ZeBoxx]

Ideally, volumetrics would write to the G-Buffers (AfterBurn, for example, does).

By lack of that, though, the only things you can directly key off of are color/brightness and alpha.

That said.. you -can- of course envelop your atmospheric by geometry which has been set to be 100% transparent. Give that geometry an ObectID to key off of, and then you can limit effects at least to whatever is contained within that volume.

This would allow you to glow, for example a red dying sun whilst not glowing the red lettering on a spaceship that's flying by.
( or something like that - I'm not a writer ;) )

[nuclean1]

FatAssasin,

You might want to try Lenseffects Flare under Video Post. Just select your atmospheric gizmo as your node and you should have it.;)

Here's a sample of what I made a while ago.

[FatAssasin]

Thanks for all the great suggestions. I really appreciate it. :thumbsup:

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