Help with Multiple reflection issue

[LewisJT]

Hi,

I’m having a render anomaly with overlapping glass and mirrored material and would be grateful of any help you can offer.



I’m creating an infinity mirror (see 01.) which I achieved with two mirrored panels and lights placed in between (see 02 & 03).

The light bounces to infinity and by hiding the outer panel from the camera we can see the effect. In reality this is created with a two mirror on the outer face.

However with I place a panel of glass over the top I lose the effect. (See 02 bottom left of box)

I have Turned off visible in refraction (see 04.) on the outer mirrored object, as I was having issues with refraction (see 05.)

This is causing an issue as I’m trying to apply a frosted effect to the outside of the mirror and have glass objects in front of the mirror.

I hope this makes sense. I have MAX files that I can supply if required, and available if you wish to chat.

Thanks in advance guys

Lewis

[LewisJT]

Extra image of lost effect, and ignore the chat part

[Morbid Angel]

just set the max reflection / refraction depth of the glass to 20 and you will be fine.

[Mokiki]

To be honest it seems like a bug even with a max depth of 900 the effect still disappears.

[Morbid Angel]

No I doubt its a bug. Can you post this scene for evaluation?

[LewisJT]

Hi Guys,

Thanks for the quick responses. I concur. I set the the max reflection / refraction depth of the glass to 20 and above with the same effect.

Max file to follow

L

L

[LewisJT]

Here you go Guys.

[LewisJT]

had to quickly remake the scene. This is what is in the zip 2017.

Cheers L

[LewisJT]

Here you go Guys,

I found the original file.

Hope this helps.

L

[Morbid Angel]

can you resave it as 2016, I don't have 2017 yet.

[LewisJT]

Hi Dimitry,

I've just left the office 21:45 U.K. Time. 🤓 And have no pc at home. I'll send through first thing tomorrow.

Thanks again

L

[Rens]

Hi, I just did a quick test and this works well when staying close to how it works in real life. Like you mentioned it's two mirrored sheets. The back sheet is very likely a standard metal backed glass mirror (like the one at home and bathroom, glass with a layer of metal on one side) and the front one likely a 'one-way mirror' (like the one in police shows in interrogation rooms. ). This front one is basically a sheet of glass with a very thin layer of metal applied to one side of it, so thin you can partially see through it. Basically it's a standard mirror with a much thinner layer of metal.

For a quick setup you can do this:
Create three planes:
A) Facing towards the camera, place this one in the back.
B) Facing away from the camera, place this closer to the camera.
C) Facing towards the camera, place this close to B), but just a bit closer to the camera.
So it's A>....<BC>. You place your lights in between A and B.

Create three materials:
1) VrayMat with 100% reflection and 100% refraction. Have Fresnel enabled. No diffuse.
2) VrayMat with 100% reflection, no Fresnel enabled. No refraction and no diffuse.
3) VrayBlendMat with 1) in the base and 2) as the coat. Leave the blend amount colour, this will blend it 50/50.

A) gets mat 2).
B) gets mat 3).
C) gets mat 1).

This is basically how it's set up in the real counterpart, except that I left out the standard mirror's glass layer (no need unless you need to come very close up because it will add a faint extra reflection that's there in reality but will need more reflection/refraction traces).

I tried with spheres with a VrayLightMat. Adjust the BlendMat colour for deeper/shallower reflection dimming, adjust the brightness of the lights accordingly as more light trapped inside for bouncing around means less leaving towards the viewer.
Just render like this with enough reflection/refraction depth in both the mats and the render properties if you have it clamped there. No need for any visible to refraction/camera flags.

[Rens]

Pics!

[Svetlozar Draganov]

I see Rens already shared a very detailed tutorial how this can be done but since I found a way to get the desired effect with the original scene I decided to post it just in case.
So instead of disabling the refractions of the front mirror object generally, disable them only for the glass objects in front.

scene:2016-11- 28_origional Infiety Box file02.zip

[LewisJT]

Guys this is great, thanks for the huge support.

I'll try in my scene later this afternoon.

2015 version for anyone interested in having a play.

L