why is taking a photo an illegal search?

In at least one SCOTUS case, it was ruled that the use of a FLIR camera is
illegal because the output of the camera revealed unusually high levels of
heat eminating from a house. Thus, constituting a "search".

Personally, I disagree. As did at least 4 of the justices.
The camera merely takes a special type of photo. The difference being in
what you see.

SCOTUS thus ruled that this type of "search" required a warrant, which the
officers did not have, and thus negated the conviction.

In their opinion, they said these types of cameras were not available to
the general public. Even though your neighborhood Walmart ain't likely to
sell these high priced cameras, they are available to anyone who can afford
them. All you need to do is to look around a little and you'll soon find
one.

I believe this is one time SCOTUS got it wrong. I say, allow the use of the
cameras. Then law enforcement can help themselves in tracking down where
the most likely "hot spot" is. With proper investigation, they can obtain a
proper search warrant.
.