How to Render Bloom on Emissive Materials with Alpha in Octane?

[Delizade]

Hi
I have several HUD objects in my scene with emissive materials, glowing like neon. A strong Camera Bloom effect is applied to them. When rendering, I need to export these neon HUDs together with the bloom effect over a transparent background. However, I couldn't achieve this. When the alpha channel is enabled in the render settings, the bloom effect disappears.
I tried using AOV output with a Light Pass to isolate the lights and then applied a bloom node on top, but this AOV cannot be exported with alpha.

How can I export the neon lights together with the bloom effect and alpha transparency?

thank you

[bepeg4d]

Hi,
the easy fix is to go to Render Settings/OctaneRender/Output AOV Compositor, press the Add Input button, then create a Solid Color Layer sets to Black, and a Render AOV Layer set to Post effect, with Blending mode sets to Physical|Add:

Then you can use the Out1 AOV in compositor in Linear/Add mode on top of the Alpha Beauty pass.

Here is an example scene:

AlphaPostAOV 2.zip

(93.79 KiB) Downloaded 3 times

ciao,
Beppe

[skientia]

This appears to be a duplicate of this post, which received replies.

An example of emissive "area light" with glow/bloom from Octane and obstructing pure black planes.

Demonstrated on two different programs supporting OpenEXR and 32-bit float signal processing with identical results: