Summer street, Boston, LWIR

[Andy Perrin]

 

 

[Stefano]

Nice!

 

It really looks otherworldly, alien, even "robotic" in a sense. Imagine a far-away planet, inhabited by an industrialized civilization, where everything is metallic. I may have a little too much fantasy, but this is what the first B&W image triggers in me. I still have an 18 years old brain that didn't fully develop yet, can it be that?

 

Also, imagine stretching the wavelengths up to the THz band... what would you see? Well, a lot of black haze, THz waves do not travel far in air. Where is the next atmospheric window?

[dabateman]

Nice!

 

It really looks otherworldly, alien, even "robotic" in a sense. Imagine a far-away planet, inhabited by an industrialized civilization, where everything is metallic. I may have a little too much fantasy, but this is what the first B&W image triggers in me. I still have an 18 years old brain that didn't fully develop yet, can it be that?

 

Also, imagine stretching the wavelengths up to the THz band... what would you see? Well, a lot of black haze, THz waves do not travel far in air. Where is the next atmospheric window?

 

Seems like Andy's photos have inspired you to write some Science fiction.

Boston was a great place for Science fiction conventions.

[Andy Perrin]

Hah, thanks. Here is another one. Same street, a little down the road.

[Stefano]

You can see all the hot engines of the cars!

Also, are those birds in the upper left corner of the first image?

[Andy Perrin]

Yes, to the bird question. Incidentally this is an example of a LWIR photo with the sun shining, so you can see reflections mixed with emissions from the objects in the scene. (It can be hard to tell a reflection from the sun heating up the surface and causing emission, though. Clue is when the sun goes behind a cloud, does the "reflection" disappear or not, but you can't see that in a photo.) Obviously because of the sunshine reflections, it's impossible to read off temperatures from anything in direct sunlight since you don't know what proportion is reflected vs. emitted. The rule "reflectivity = 1 - emissivity" depends on the scene and light source being nearly the same temperature, but this is a very bad approximation for the SUN, at some 5500 degrees C. It works fine when there is only emitted light from other objects in the scene, though.

[SteveE]

I am a little surprised that the engine area of the cars is generally so uniformly bright, and that there is such a sharp transition between the engine area and the cooler parts of the cars. I would have thought it would be more diffuse.

[Andy Perrin]

Nope, that's pretty typical. Cars are made of metal, mostly, which is a good conductor. You go a few inches away from the heat source and the temperature falls to atmospheric. It's with good insulators that you see a more gradual transition.

[Stefano]

You can verify it by touching the car. The side doors aren't warm because of the engine.

[dabateman]

You can play spot the Tesla. I think I see one in that photo.

I love how the wheels are red due to braking.