Vray brute force glass problem with 2 objects !!

[Bigguns]

Hi,

this really annoying bug is there for a while.. if not.. ever .. and it would really need to be fixed.. I remember someone posted a glass render comparaison between vray and corona, and in corona it was looking so much better, much more clear .. in vray it just get DARK in brute force especially if you have a 2d object..

So, if you have 2d object and you render those object with irrandiance map it's not bad... but you just switch it to brute force.. and it get dark.. and it's IMPOSSIBLE to get as clear as in Irradiance map... and it's realllly annoying.. expecially for thin liquid in the eyes let's say...!

Here's some images.. let me know if you need the max file Vlado, or you can just recreate it, I used 2 planes, make them concave and curved , with a plane as a BG , and some layers of plane. Glass set up : Affect shadow on of course, max depth 38, Glossiness 0,86 and IOR 8,0 .



Compare the images you'll see right away what I mean.. and it's really annoying.. should been fixed a while ago.. surprise not much peoples reported it.. I remember some have noticied it like me .. but I'm always surprise its still there every upgrade of vray.. when can it be fixed? It's very limiting the realism of the eyes and other 2d glass stuff..

thank you

[Morbid Angel]

please post the scene.

[Yves Adam]

just out of curiosity, when you say 2d, I take it you mean without depth ?

how do you expect refraction (like glass has) to work on an object without depth ... the very nature of refraction is light traveling through a transparant volume

[Bigguns]

in all the other renderer it work well.. and even in vray it work well at least much better in irradiance map then brute force. how do you explain that ^^

[Bigguns]

BTW, my lighting was with an HDRI in a dome light thats it, it's important because the effect is much worst when working with hdri and dome light in brute force.

[Bigguns]

here's the scene, just switch between irradiance map and brute force.. and youll see the glass will be much darker with brute force.. and you need an HDRI I could not add it to the zip was too heavy for uploadglass bug scene.zip

[Morbid Angel]

here's the scene, just switch between irradiance map and brute force.. and youll see the glass will be much darker with brute force.. and you need an HDRI I could not add it to the zip was too heavy for upload[ATTACH]27876[/ATTACH]

I had a look at your scene. I honestly think there isn't anything wrong here.

See attached image. If anything irmap is producing a darker render then bf.

There is a problem with your glass setup. When you trace multiple layers you set the refraction depth to 38 but the reflection depth is set to 5, so reflection is clipped off early on. Secondly, dome is not refractive, so you need to place your hdr into environment slot (refraction) so it shows up in the dark parts of the glass, otherwise you get black there (from environment) not from the dome.

here is the scene:

https://drive.google.com/file/d/0B-S...ew?usp=sharing

here is the comparison

[Bigguns]

here for comparaison, even Mental ray has it right. Image without thickness to the glass and with thickness.. compare to Vray.. look's much better in Mental ray... Slow as hell, but look's accurate.

[Bigguns]

Just saw you'r post, tested it and work's just fine, shit it was my bad haha, sorry guy's ^^ . I did not knew that dome light was not having effect in the refraction... but was starting to think it has something to do with environement refraction. Anyway, a must to know

I had a look at your scene. I honestly think there isn't anything wrong here.

See attached image. If anything irmap is producing a darker render then bf.

There is a problem with your glass setup. When you trace multiple layers you set the refraction depth to 38 but the reflection depth is set to 5, so reflection is clipped off early on. Secondly, dome is not refractive, so you need to place your hdr into environment slot (refraction) so it shows up in the dark parts of the glass, otherwise you get black there (from environment) not from the dome.

here is the scene:

https://drive.google.com/file/d/0B-S...ew?usp=sharing

here is the comparison

[ATTACH=CONFIG]27877[/ATTACH]

[Bigguns]

Finally no, you changed my IOR, let the IOR at 8, you'll see, it's dark!

The mental ray render I posted was with a 8 or IOR also. Why in Vray it get darker the higher the IOR ?? It's not normal..

[Morbid Angel]

When you lock reflection ior to refraction ior, then set ior to 8, this makes the glass almost fully reflective like chrome. Its not surprising that you can't see any refraction at that point. I don't know how mental rays shader is setup, but it would most surely do the same thing.

[Bigguns]

So how can you unlock these?

[Bigguns]

I treid to blend it, so removing the reflection component of the glass with the IOR of 8 and blending it with a vrya mtl that just have reflection in shellac mode and it's dead slow in the material editor.... seems to work though..but so slow now it's freezed :S I doubt in real life.. the more IOR you have the more the surface is relfective... to me it's 2 different thing.. no ?

[Morbid Angel]

there is a lock Fresnel button under reflection section of vray mtl. You can unlock it and then control the ior for reflection separately. It works as expected, and there is no need to use any blend method.

[Bigguns]

There is still a problem with brute force, I removed the reflection component ( turned off ) and as you can see, in IOR 8, there is a huge difference between Brute force and IR LC . Without the shell modifier. BTW it's same setting as in your scene and mtl but with IOR at 8. When they have the shell modifier to on, they both ( brute force and IR LC ) look the same pretty much, but without thickness, in BF it look's much darker.. wich is bad.. expecially for eyes, lacrymal liquid.. I remember, even Christopher from Chaos group on digital emily 2.0 could not get the lacrymal liquid crystal clear because of that.. it's a problem in brute force with 2d transparent objects.