I'm trying to render some artifical object behind glass.
This object has its material properties in such a way that it produces refraction (raytrace transparency with IOR > 1), reflections, and it casts a shadow.
I use a real-life image as a background to render the scene, you can see the results before and after the process: http://www.youtube.com/watch?v=30pFzvcwQnc
Please note that the model is not an accurate representation of the real object (I'm ok with that).
I want to get rid of the transparent model on the right image and keep only the distortions on the apples, the reflections of the apples on the object and the shadow cast upon the table (there is no real table in the model, it's just the image)
It should look like the original object (the glass on the left image) is casting the shadow and producing the refraction and the reflections.
As the model is an approximation of the real thing, it is ok not to have accurate distortions.