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Message: <blockquote data-quote="tarchon" data-source="post: 1257471" data-attributes="member: 5990">In order to have an image, you need kind of need more than 2 data points.  It is likely that the snake does develop a rough notion of the position of the IR source by "scanning" its pit organs, moving its head around, but I've never seen any evidence that this information is internally mapped to an image.      It's an extremely difficult (and slow) information processing problem to take a 2-element detector and construct an image by scanning it in a non-rectilinear 3D pattern.  It's doable with a 1D detector array (which I know since I'm doing it), but it's not easy, and 2 points just won't give you enough information for pixel matching unless the detector motion is known very accurately.Active IR is totally different. With the emitter, what you have is basically just an invisible-beam flashlight.  It isn't really sensitive to thermal radiation unless the radiator is really hot.  Even active IR systems in the MIR and FIR can have problems with nuisance radiation though.  Usually, an active system works in the NIR band, where thermal radiation isn't a big problem.  Active IR is mainly used for the sake of being invisible to the naked eye rather than for thermal imaging, so there's no strong motiviation to make it work beyond the NIR.</blockquote>