reflection/shadow of text on glass

[mitchino]

I constantly run into problems whenever I render graphics on glass in Octane with double reflections, internal reflections, shadows etc.

I'm rendering a perfume bottle and the problem is bothering me gain, see pic.

I've seen posts before where people say this is how it is in the real world, the graphics are reflecting on the inner surface of the glass, but I have the real bottle in front of me, and I cannot see any double reflection or shadow and cannot reproduce what I'm seeing in Octane.

Is there a fix for this?

[mitchino]

So I seem to have minimised the problem by using UVW mapping rather than cylindrical mapping. There is a faint reflection of the text on the inner glass, but it looks much more natural.

Why is it that cylindrical mapping causes this problem?

[bepeg4d]

Difficult to say from your screenshots, try to use the Beauty and InfoChannel passes to better investigate the issue

ciao Beppe

[AWOLism]

I'm guessing that the cylindrical projection projects the text on both the inner and the outer surface of the bottle mesh, unless you use different materials with selection sets.

[jayroth2020]

AWOLism is correct, as the projection would appear on both sides of each polygon. In the case of thickness, assuming a quasi-realistic modeling of the glass, you will have a separation of outer to inner faces. A simple projection will capture all of the faces without discrimination. A selection tag isolating the specific faces to a given material can help to mitigate this, but you will still have reflection ghosting, as you would in a real glass. You can use a Rayswitch node to further tune the result.