How does an object look when it is viewed through an opaque object?

we cannot view through an opague object since it does not alow light through but only cast shadows

Nothing CAN be viewed through an opaque object.

In order to "view" anything, you have to receive light from it. But an opaque object absorbs any light that hits it, and no light comes out the other end. That's what "opaque" means. So if the opaque object is in the path of the light you're trying to view, then the light you're trying to view can never reach you, and your attempt to view is doomed.

Here is a real-world, every-day example of this scenario:

- - Stand outside of your best friend's house.

- - Try to view her through the living-room wall of the house.