There are a lot of things that are opaque to normal-band light that are transparent to other things, like infrared, ultraviolet etc (and vice versa). This goes

There are a lot of things that are opaque to normal-band light that are transparent to other things, like infrared, ultraviolet etc (and vice versa). This goes for more than just light. It all depends on the wavelengths. One should not assume that simply because a human can't see through it, doesn't mean a computer with the right kinds of sensors can't.