Crazy ior!

[3d-Soul]

Hello,

I'm working on an exterior night scene and have a confusing issue that I've never had until now.
my workflow is that I first put some vraylight inside the building and then start to set-up extrior lights. I have
a big single object for the windows' glasses so I could exclude it from material override, but as you can see in
the attachment I have a odd refraction/reflection in my windows with ior value of 1.6 that always I use. I tested
some other values (1.3,1.1,...) to find the answer but finally I was forced to hide window object to prevent from
probable unwanted issues!

any help on this problem would be appreciated. thank you.

BTW I'm using vray 2.4.03 and 3ds max 2013.

[CAMedeck]

Is your window object using the correct thickness for the glass?  I've seen where planar glass objects do something similar.  Adding a Shell modifier set to a half inch or so corrects that.

[3d-Soul]

Yeah, I always do real scale modeling. The glass object have 0.6cm thickness. there's no overlapped faces.
today I have some extra times, maybe find the answer but don't deprive me of your comments.

[3d-Soul]

Didn't find any solution. maybe it's a vray bug or something.

I did a few test renders with iray, mental ray, vray RT and it looks good in iray and mental ray.

the attached zip files includes renders and the glass object if you want to give that a try.

[3d-Soul]

don't know why but I can't see my last post. my post counts are rising but I can't see them.

Edit : it should be related to the attached files because I can see this post right now.

[Steve_Curley]

Which one(s) can't you see? There are 4 posts in this thread (before I posted this one), 1 from camedeck and 3 from yourself. If I check your latest posts the 3 most recent are the 3 in this thread.
If you're convinced there should be more then a post in the Website Support Forum might be appropriate.

[3d-Soul]

Yes Steve, there are 2 or 3 more posts (although all of them should be similar because I couldn't see my post and had to repost it).
OK, I'll post there. thanks.

[3d-Soul]

just for testing my post visibility !

I attached other renderer results and my glass object here if you want to give that a try.

Edit :

Funny ! it worked! anyway... Didn't find any solution. maybe it's a vray bug or something.
I did a few test renders with iray, mental ray, vray RT and it looks good in iray and mental ray.
the attached zip files includes renders and the glass object if you want to give that a try.

[Stefan_L]

I know a similar effect, caused by Cutoff Threshold values reater than 0.00 in Arch & Design material, Advanced Rendering Options group. It basically ignores those phenomena below the threshold which leads to circular borders between a little and nothing.

[3d-Soul]

thanks Stefan for comment.
turning "Reflect on back side" option on (VRayMtl Option rollout) improved the result but I think there's still a difference in darkness between left and right side. see the attached GIF file please.

[Stefan_L]

I don't know anything about VRay, so I'm not much of a help there and won't dare to suggest:

"Use mental ray or iRay then, it renders fine." 🙂

Does rendering a perspective view instead of a camera (or vice versa) change anything?

Are the face normals correct?

Does it happen with a box + shell modifier too?

Is it caused by reflection or by refraction (or both)? Try a mirror material...

[3d-Soul]

Thanks stefan. I'm also a mr and iray user, but IMHO vray is simpler to setup, specially in interior cases. Yes, I've already checked whole your guesses. About your third question the answer is Yes, provided that I have several copy of these objects (something similar the above attached object). For last question, I think it's related to both, reflection and refraction. Anyway I completed the project and sent it to my client. They will have cold nights! I just wanted to know the solution and any more answers would be appreciated.