1 Dwalin: I thunk 'tis gettin' lighter. We moost be approochin' thu ind o' thu toonel. {translation: I think it's getting lighter. We must be approaching the end of the tunnel.}
2 Draak: Yes. Light mess with Draak heat sight.
3 Mordekai: "Heat sight"? Wait a minute. You have infravision? You can see in the dark? Why didn't you tell us?!
4 Draak: Not same as see in dark. Bare rock not show heat...
4 Mordekai: Don't give us your primitive pseudoscience excuses!

Again 1st Edition Advanced Dungeons & Dragons comes to the rescue. The 3rd Edition rules have some newfangled thing called darkvision, which apparently allows those who possess it to see in pitch blackness exactly as they would be able to if there was light. Yeah, yeah, I know it's fantasy, but that's just lazy. We had a perfectly good thing called infravision that worked with heat signatures, and was cool because it was different and based on real-world physics and geeky.