VRay glass problem, need advise

[salvador]

Hello,

 

I need advise on a glass issue. I don't remember having this problem before VRay 2.0.

 

This is a house I'm working on. In the image "no-glass" I rendered the room without glass and everything is well exposed, peachy and clean enough for my 1 - 2min tests.

 

When I unhide the glass I put on windows, the problems begin:

 

1. The overall lighting is too dark.

2. The render gets blotchy. I have Vray light planes on openings and if I turn them off

I get less noise but more blotchiness and still dark.

3. The sky looks dark. I have a VRay HDRI override becuase I want to see some clouds outside instead of the pure VRay Sky.

 

I used the VRay Sky in environment skylight override to get it to light up the scene, because I think it's faster and gives better quality.

 

So, What's wrong with the glass? I've used these settings for quite some time but only recently I've been having these problems.

 

Thanks in advance.

[AubreyM]

A few suggestions:

- Place the HDRI in the refraction override slot as well.

- Turn down the reflection amount, it looks like it's pure white/255.

- Up the subdivisions for reflection and refraction

- try lowering the IOR to 1.2/1.3

- You could also try to use a falloff map in the reflection slot.

[salvador]

A few suggestions:

- Place the HDRI in the refraction override slot as well.

- Turn down the reflection amount, it looks like it's pure white/255.

- Up the subdivisions for reflection and refraction

- try lowering the IOR to 1.2/1.3

- You could also try to use a falloff map in the reflection slot.

 

Thanks! LEt's try that.

 

PS. Did you have these problems before?

 

Edit:

 

Nope. No change. Tha glass is still cluttering the scene. I even tried fog color to white and mult. to 1.0 and 0.0. Still the same.

Edited September 1, 2012 by salvador

[AubreyM]

What happens if you turn reflections waaaay down to almost nothing and the IOR to 1?

I also forgot to ask, what are the windows? a plane,box?

[Tommy L]

turn off the .oo4 fog and your problem will most likely go away. You can also go into the max object properties and tell that object not to cast shadows.

[salvador]

Bahhh!!!

 

Someone can figure it out? Because I don't.

 

I did what I usually do when things don't go right. Start over. So, I made a new fresh scene and did the typical flipped box, sun+sky, physcam, almost all at defaults and it came right; then windows and glass and it came right again.

 

So I merged my house in and it still came right. What changed? The only downright difference (and it doesn't make much sense to me) is that in the old one it overrode the materials to a Vray mat with edges tex on diffuse (except for glass) and in the new one I set all geometry to Vray material straight off (both gray 128) except for glass. See the result:

[Tommy L]

So its working in the new scene?

[salvador]

The glass on the rightmost window is barely visible because of the strong sunlight coming in but it's there and the glass settings are almost identical:

 

- diffuse to black

- refl and refr almost white (but not pure)

- fresnel and IOR identical

- fog to the same green but at 0.03

 

any thoughts of what could've happened?

 

THANKS TO ALL FOR REPLIES !

Edited September 2, 2012 by salvador

[salvador]

So its working in the new scene?

 

Yes Tom. I haven't rendered the other parts of the house but as for the great room we are go. I guess I'll have to be extra careful not to mis-tweak the settings. lol

 

Thanks again.

[Ricardo Eloy]

Try this:

- remove shadow casting from the geometry's properties (even though the material is already using refraction to control the shadow density)

- in the geometry's V-Ray properties, remove the glass from GI. It will likely not affect the look of it, but will make sure everything GI-related will simply ignore the glass, as if it was not there.

[salvador]

Try this:

- remove shadow casting from the geometry's properties (even though the material is already using refraction to control the shadow density)

- in the geometry's V-Ray properties, remove the glass from GI. It will likely not affect the look of it, but will make sure everything GI-related will simply ignore the glass, as if it was not there.

 

It's working now but I could still try that one too. For Vray properties, would it be generate and recevie GI? or just invisible to GI?

 

thanks fot the tip.

[salvador]

Ok. So the render came up really nice. Just one doubt here that might've been the cause of the problem. Suppose I have a glass panel which is an Editable Poly and I add another Edit Poly modifier only to chamfer the edges. Then I apply the material which is contained inside a Multi Sub-object material (I keep it like this for convenience); this Multi has aluminum, glass, frosted glass and rubber joints materials. So I set the glass panel to use the Multi's channel 3 (the glass shader) in the Edit Poly modifier but I forget to set the same channel for the base Editable Poly which in turn may take a channel X (whatever number). Does this make sense? Is it possible that the "mix" of channels makes the glass this bad? It just sparked in my mind now and I haven't tested yet.

 

Thanks anyway for the help and I consider this thread "solved".