# Render a surface transparent only if directly visible

I want to render some glass, in order to actually see something it requires a background. However I want the glass object to have a transparent surrounding. How do I make a background which is considered by the refraction of the glass but is transparent when it is seen directly by the camera?

• I'm not sure if this is possible in BI, but it's pretty easy in cycles. – gandalf3 Aug 11 '14 at 17:48
• Unfortunately I need a solution for BI – Machtl Aug 12 '14 at 6:06

• I should add that for this to work in the Options category of the material Traceable must be checked. – Machtl Sep 10 '14 at 14:07