What is the best way to get a mask of this refracted chair?

[actrask]

I guess I can make the chair self-illuminate 255,0,0 or something, but is there a more elegant solution? [see attached]

[actrask]

After searching around, it sounds like the answer is "you can't". I was able to get it by applying a ray switcher to the chair with a material only in the 'Refract override' no diffuse, self-illum set to 1.0. Apply a flat black material to everything else in the scene, and then render just the glass. It's best to save a scene state before doing all this.

If there is an easier way I'm all ears!

edit: set the self illumination color to 255,0,0 (or whatever) and turn off any post effects in the frame buffer.

[maru]

So the issue is that you do not want the glass panel to occlude the chair, right?
I am afraid this is not possible currently, but it's a critical feature and we are aware of that (it will be done).

Another thing you can try is using the render selected feature in Scene tab.

[actrask]

I need an easy way to grab a mask of the chair that respects the IOR value of seeing it through the glass.

[maru]

Not possible at this time.
You can vote for it at https://forum.corona-renderer.com/index.php?topic=96.0
"Refraction/Reflection working with masking render elements (CMasking_Mask,CTexmap, etc...)"