Well, things were going along merrily, until Blender decided to screw up my Image-to-Plane Smoke at the foot of the door. In the viewport it looked fine, but for some reason the final render revealed the plane when it's supposed to be (and should be) transparent like it shows in the pre-render. Any ideas on how to remedy this glitch would be greatly appreciated.
@jonathanwilliamson: I think I have the transparency bounces set to 32 max & 32 min. Although I went with another option for that effect, should I change those values to higher? Thanks JW
@lhumungus: Not corroded. Frosted. Because they are cooling pipes.
Awesome. One minor comment for flavor: the pipes on the right stand out as weathered and corroded while everything else looks clean and pristine, even where I'd expect dirt/rust/etc.
check your transparency light bounce max settings in the render settings, I doubt it is the issue but it has tripped me up in the past with alpha image plane rendering on spiderwebs. Failing that , it looks a bit like the strong line in the render is the edge of the plane, maybe try moving it out of shot? But if you are layering up multiple alpha planes then the first suggestion might work...