Strange dome reflection on glass

[penumbra]

has anyone experienced or seen this? using default sun sky the vray glass gives a strange dome like reflection. glass geometry is a simple thin (1") boxes.

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[penumbra]

Anyone? Anyone?

Thanks for your help.

[Box]

I knew I'd seen this somewhere before, don't know if this thread helps but ......
http://sketchucation.com/forums/viewtopic.php?f=322%26amp;t=56461

[andybot]

yeah, delete your refraction layer from your glass. Or else give your glass a thickness (two planes instead of one, with proper orientation - so you don't see backfaces either from outside the building or inside.)

[penumbra]

excellent, many thanks. I just turned the refraction transparency to black and that did the trick. But I wonder now if my glass will be refraction-less. Why have the refraction layer at all?

Thanks again.

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[rspierenburg]

I believe thats what Andybot was getting at. If you don't have thickness to your glass you don't need the refraction layer at all.

[penumbra]

@rspierenburg said:

I believe thats what Andybot was getting at. If you don't have thickness to your glass you don't need the refraction layer at all.

Perhaps except my glass is a full solid of 1" thickness...

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[andybot]

@penumbra said:

Perhaps except my glass is a full solid of 1" thickness...

That's why I asked if the faces are oriented correctly... It will also give you incorrect refraction if both normals are facing the same way. You have to have both backfaces facing towards the inside of the glass pane.

[andybot]

@penumbra said:

excellent, many thanks.

You're welcome!

@unknownuser said:

Why have the refraction layer at all?

For many render engines - "architectural glass" or "thin glass" gives you the same look when at the scale of a building, there is effectively no refraction. It's such a small volume of glass that it doesn't matter if you have refraction calculated or not.