Glow Through Transparent Object

[Brian Jones]

Post effects (Glows etc) usually can’t be seen through transparency because it is rendered first and glow is added later. Someone has a depth of field plugin that does dof through transparency but I don’t know of any that does the same with Glow (which doesn’t mean it doesn’t exist…)..
Shape will likely be a problem but the glow of a Visible light can be seen through transparency.

[Brodd Nesset]

This is a limitation of the ‘Glow’ you can add in the standard Material editor. Unlike the other channels, it is not really a channel but a post effect, and it would be tidier if you had to add this type of glow as a tag to the object in question. I guess it’s there in the Material editor because it’s ‘always’ been there and out of compability.

You can make two renders: one with the bowl disabled so that the glow will show properly, one with the glass bowl and no glow. Then compose the two in Photoshop (or After Effects) via an appropriate blending mode.

Instead of the glow effect you can make a fog material larger than the flame; yellow fog will appear through glass.

Probably best: you could also render a visible light. Put an actual light source inside the flame, an Omni or perhaps the Tube shape, with Visible light checked and Volumetric selected. Note that with complex settings volumetric light can take a long time to render, so experiment with a low/standard setting first.

Her lips said “no!” but her eyes said “read my lips”.

[Tom Slattery]

That last tip worked great!

I used an omni and turned on falloff at a small radius so it didn’t flood the scene with light.

Thanks!
~TPS

[Brian Jones]

you can also either turn off Diffuse for the light and it will only have specular highlights left or check off No Illumination – it won’t cast any light but you will still see the visible glow.

[Jan Vork]

My solution to this problem is creating the bulb material with a Fresnel on the Luminance channel. You can turn the Luminance very bright (>100%) and let it fall off to the edges of the bulb/sphere. With a little tweaking and in some cases adding extra geometry around it, with speculars or reflection, the result can be very convincing, and fast rendering. Remember that a light not actually glows without a moist or dusty environment (or a lens effect), so in cases where there’s only a clear atmosphere the brightness is the most important parameter to achieve the lightbulb effect.