It doesn't really say it affects the 3D. The problem thay had is that water would enter the 3D cameras and stick
to the mirror(s) which would break the 3D effect, that's why they decided to add the rain in postproduction. I'm
sure future versions of 3D cameras will be "waterproof" to avoid the problem. In the beginning of 3D there were
a few movies that used 3D more or less as a gimmick but those times are mostly past. In my opinion 3D in the
hands of skilled filmmakers like James Cameron, Ridley Scott or Peter Jackson doesn't hurt the filmmaking
process, is just add another dimension. (Pun intended).
I thought beginning shots of Prometheus looked absolutely beautiful in 3D and it was just waterfalls and dry lands. I am more than ready to be blown away by the amazing scenery of New Zealand. []