I did a bit of net research after posting last night. I found 2 different sites that said that pit vipers process their heat pit info in the vision centers of the brain. I found no info on python heat pit sensory processing. I also found it pretty much everywhere that the pits detect infrared, and not radiated heat. Makes mucho sense since sensing heat directly would offer almost no range, and pretty poor direction calculation. Just think about convection currents. I dont know if this has been proven, but I can imagine it wouldn't be hard. Isolate receptor cells, and see if infrared stimulates them to fire electro-chemical signals to the nervous system. Even easier...can they sense heat through glass? Glass insulates pretty well against subtle temp fluctuations. If so, it pretty much has to be IR.
I still dont think of it as "seeing". Seems like more of a 6th sense to me.
1 adult bull snake: "Dozer"; 1.1 juvenile bull snakes: Oscar and Phoebe; 3 baby red-sided garters; 1.1 macklot's pythons