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UltravioletPhotography

Some LWIR photos


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Andy Perrin

These are all panos made with my FLIR E60. I have recently obtained the 15 degree field-of-view lens since FLIR has overhauled its product line, and the 15 degree lens is being discontinued, along with the FLIR E60 itself, so prices are slightly lower now.

 

Processing notes:

The original FLIR images had the raw extracted with EXIFtool, had the histogram adjusted in a batch operation in MATLAB so that all photos were corrected to a common max and min value (to avoid contrast differences between photos when stitching). They were then stitched together in Panorama Stitcher (a Mac program that handles lots of small images particularly well), had shadows raised/highlights lowered using Aurora HDR, and colorizied in MATLAB.

 

post-94-0-00059600-1590692387.jpg

 

post-94-0-63966000-1590692399.jpg

 

The photographer and his new lens:

post-94-0-83729200-1590692966.jpg

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Finally I see you in visible light! I imagined your face to be different, that's normal since I never saw it.

 

Certainly a narrow field of view lens helps, since you get smaller tiles keeping the "high" resolution of your thermal camera (the resolution is not very high, but that's the point for doing panos).

 

Did you shoot them in nighttime, as usual for you?

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Andy Perrin
Yes, these were shot mostly after midnight, to give everything the chance to cool off a bit. One amusing effect of cooling (which I should show sometime) is that signs, which are readable in the day time due to black print absorbing visible light better than white backgrounds, become blank as they reach a uniform temperature in the darkness. So if you shoot a time lapse movie, you should be able to see the text fade away. A project for the future!
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So, basically they have a uniform emissivity in LWIR (uniform amount of blackbody radiation at a uniform temperature), but not in visible light (clearly non uniform absorption, otherwise you couldn't read them).
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I had a feeling these should start to come down in cost.

I have been getting ads for other heat detection cameras with facial recognition.

Fun times moving forward.

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Andy Perrin
The camera hasn’t come down in cost, just the lens because they discontinued the line (pre-COVID). The price was only 10% off too. It wasn’t all that great a deal, but I was afraid they would become unobtainable if I waited. The FLIR lens system is proprietary.
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Yes I see. Just search for FLIR and still way way outside my budget.

I also haven't seen too many discounts generally either. Cost of things I have been interested in has actually gone up.

 

Congratulations on your lens purchase though. That seems very useful focal length, especially for your panoramic images.

But though lens are not only proprietary, but tricky. You can't just grab any old glass lens and modify the mount to work. Completely different system.

 

Hopefully the cost of more SWIR and LWIR systems comes down. Not just these scary security systems that are just missing the linked tranquilizers dart armed drones to take out high temperature offenders.

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It was interesting to read about your MATLAB histogram correction.

 

Please, tell me ( again, probably? la! ) what is going on along the sidewalk edges heat-wise in the 1st photo? And on the porch steps?

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Andy Perrin

Please, tell me ( again, probably? la! ) what is going on along the sidewalk edges heat-wise in the 1st photo? And on the porch steps?

The steps probably heated up uniformly in the daytime with sunshine, and then at night the corners and edges cooled first.

 

I did a computer simulation with a student a few years ago of a block of steel cooling off and you can see the same behavior there:

post-94-0-72648000-1590770055.jpg

 

If you bake, you've probably noticed this too. The corners and edges are the first thing that cools.

--

 

Another thing that's going on is that the grass/dirt has a lower heat capacity than asphalt/concrete, so it cools off faster. That's why the grass is purple but the curb is orange/yellow/white. (There has been talk about running pipes under parking lots to use the heat stored by the asphalt to provide hot water for the malls, etc.)

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