Reflections/Refractions alpha issue

[Gro]

Apologies if I'm looking at this wrong or answer should be super obvious (and please correct me if so), but the following doesn't seem correct.
Glass-like material complete render, and one with a grey box behind, looks fine until you take into account the alpha...


Alpha with reflections and refractions affecting all channels:


Above appears too dark? Resulting in overly transparent image:


Whereas the two alphas individually rendered appear more correct:
First, alpha with reflections affect all channels, and refraction color only ...and... Second, alpha with reflections color only, and refraction affect all channels



...I can composite/matte separately, but it seems like I'm working around a strange issue... or am I being dumb?

Thanks!

This example scene:
ReflectionsRefractions.zip

[Gro]

Presuming not a simple workflow error?
Emailed to support:

Title: 'Reflections/Refractions alpha issue - 3ds max'
21:22 10/18/2016

ticket #966143

[Deflaminis]

Weirdly, when I render it I get this with the box unhidden.

[vlado]

There is no meaningful result that V-Ray can give you if you enable the alpha for both reflections and refractions - at least I have no idea what it is supposed to look like.

Best regards,
Vlado

[Gro]

Shouldn't the a combined alpha look something like this?

(Similar to adding the 2 alphas but actually done with via the rgb + pure white environment/reflection)

+In the original setup we'd want something like the above as an alpha, with rgb result being unmultiplied? ... Or is that around the area that v-ray runs into trouble?

Is there no way of getting at that point/info/result from the renderer? At the moment we seem to be compositing the rgb and tracing/matting in one of the 2 alphas as per effect channels option?
And when setting both refract and reflect to effect all channels/alpha we end up with something that looks like one of the alphas almost takes away from the alpha result?
... The rgb channel remaining blind/unaffected by the material option/process...?

(You'll have to excuse the accuracy - or lack thereof - of how I *think* this maybe working or not).

... Is it not possible to modify or correct this result?




Small aside/apology:

Weirdly, when I render it I get this with the box unhidden.

Sorry that is the result from the 'Glass_Refract_AllChannels' material (refract only effect all channels) which I left on the model in sample scene. Changing the material to 'Glass_AllChannels_Both' from material sample slots (both reflection and refraction effect all channels) - or by changing said options on the assigned mat - will produce results like my first example. My bad; didn't leave sample scene in clearest state.