This image was taken when the local delta-T was low. The wall framing is visible, but with little additional detail.
An image of the same wall taken under higher delta-t conditions (from a slightly different angle) reveals voids in the insulation below the top plate. A bookshelf and other furnishings are visible on the right-hand side of the image.
Sometimes it's the structure that's confusing, not the image. This late-1800s house features solid, log-cabin-like walls of stacked and spiked dimension lumber. In the absence of framing or insulation, differences in surface radiance are few and far between.
Powering up a building's hvac system can boost the delta-T enough to allow good imaging, but it can also cause uneven surface temperatures. A baseboard heating unit is responsible for the warm streaks in this grayscale image.
In this air-conditioned structure, the prominent cool area on the ceiling lies directly in the path of a supply duct.
Daylong exposure to sunlight has loaded the south-facing wall of this home with stored heat. In the image, taken soon after dark, the roofing has radiated most of its heat to the night sky.
The air-conditioned living space in the structure can clearly be distinguished from the uninsulated attic; although the image was taken after dark, the framing in both areas is visibly warmer than the fiber-cement siding, because it retains heat from the warm day.