looks like somebody used Burn tool in photoshop to darken it up. is doesn’t look like additional substance on the ground, it’s simply darker.
I agree.
I use "Canvas", which works with both vector and bitmapped graphics seamlessly -- and can apply bitmap filters to vector objects. I've gotten close to the effect with:
The big problem is that all of the transparency/transfer modes tend to intensify the background color, instead of desaturating (obscuring) it as seen in the original.
"Airbrush" tool could probably replicate the effect, but I prefer to stick to processes with mathematically precise controls for analysis work...
Photoshop users would probably convert RGB to CMYK, and then do "chops" (channel operations) on the K (black) channel. I'll play with that if I feel it's worth further effort.
Yardstick listed most of my serious objections -- specifically, no defined venting source(s) with a "nozzling" effect. (I would expect any air vents to be surrounded by a "black as coal" deposit.)
BTW & FWIW, re the limited and sharply defined (low lying) deposit area: I would expect high molecular weight (uranium containing) "soot" to fall out much closer (vertically and horizontally) to the source than would ordinary carbon soot...
Oh, well, until Google or some other public source releases an overflight AFTER the supposed event date, those of us who are limited to public OHI sources have gone about as far as we can go...
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How thick does one expect a coating of soot to be?
Cheers!