WWI's 'Dazzle' Camouflage Seemed Effective Due to Unexpected Optical Trick
72 comments
·March 22, 2025jessriedel
alexey-salmin
I had the exact same question and I think the news article didn't do a good job to answer it. But the paper does claim that his control was terrible, even though not clear why because he didn't seem to document it properly.
> After addressing problems with Blodgett's analysis and control experiment, we found results indicating a twist of only about 7°, but a much larger “hysteresis” effect (∼19–23°) where perceived direction was drawn to the horizon regardless of dazzle. This effect combined both constructively and destructively with “twist”, depending on the direction of the target ship.
Then specifically this part is very suspicious, zero error is unlikely in any circumstance:
> A uniform white and black background were assumed to produce zero errors. In the case of white, Blodgett (1919) claimed this was borne out by experiment, though no details (e.g., number of trials or observers) were provided. Furthermore, there is no evidence (or even a suggestion) that the black condition was run.
> Results were also reported for ships painted uniform black and uniform grey (e.g., see Table 2 in S2). These conditions were not mentioned by Blodgett until his results, and it is not clear under what seascape and weather conditions these controls were run, how many trials were performed, what the true directions were, or which or how many participants took part. In fact, there is nothing in Blodgett's report to suggest that these conditions were performed by any of the six participants mentioned above.
veunes
But I think the researchers' point is more about how Blodgett may not have accounted for how much that effect was influencing perception
Havoc
I suspect the effect is similar to why zebras look the way they do. Patterns and perceptions of them aren’t always super intuitive
capitainenemo
There's recent evidence that the zebra stripping helps against flies. But a fly has a much simpler brain than a u-boat captain.
https://www.discovermagazine.com/planet-earth/zebra-stripes-...
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jboggan
The last photo in the article is of my great uncle's [0] ship, the Olympic [1], sister ship to the Titanic. It's interesting to read about since he was knighted after the war for captaining her and ramming a U-boat [2] that was trying to sink her during a troop transport mission across the Atlantic.
0 - https://en.wikipedia.org/wiki/Bertram_Fox_Hayes 1 - https://en.wikipedia.org/wiki/RMS_Olympic 2 - https://en.wikipedia.org/wiki/SM_U-103
ahartmetz
The connection between camouflage and then-current art styles is also interesting. Dazzle camouflage seems quite related to expressionism (which I know mostly from film, where it's stark and unsettling like the camouflage), and the still-current pixel camo is related to, well, "computers are cool" and pixel art.
daniel_reetz
Strange take. Pixelated camouflage is and was an attempt to make a scale invariant camouflage (works at near and far distances) by encoding patterns at multiple spatial frequencies. It's far from "computers are cool" or pixel art.
ahartmetz
There are always reasons (rationalizations) why it had to be exactly like that. Like so many acronyms that are really backronyms. Or, if you are familiar with IT, why a certain technology is "needed" in a product.
I'm not saying that these camo patterns don't work, but the particulars (e.g. why it had to be rectangular pixels, not hexagons or nature-inspired fractals) are often connected to fashions. My personal opinion is that dazzle camo looks cool, by the way ;)
aardvarkr
Camo has been and continues to be very well studied. It’s actually incredible how well the pixel camo works compared to everything else. If there were anything better they would be using it
kjkjadksj
Conceivably this would be done better with more resolution and pixelated patterns are also not found in nature. Keep in mind this rolled out in an era where army recruiting was investing heavily in video games and other favorable media in effort to connect with a new generation of youth. High tech seeming uniforms are also for the morale of the soldier as much as they are for function.
IshKebab
Terrible article. What effect did the dazzle have? Doesn't say.
db48x
IshKebab
Ah ok:
> we found results indicating a twist [due to dazzle] of only about 7°, but a much larger “hysteresis” effect (∼19–23°) where perceived direction was drawn to the horizon regardless of dazzle. This effect combined both constructively and destructively with “twist”, depending on the direction of the target ship.
Could have just said that...
diggan
It's in the first paragraph? At least the effect they were looking for:
> Unlike traditional camouflage, which helps objects blend into their surroundings, dazzle camouflage used stark geometric patterns to try to confuse German U-boat captains’ perception of a ship’s direction and speed, making it harder to target.
IshKebab
That's what it was thought to do, but the rest of the article makes it sound like it actually doesn't.
simonh
It's a summary of the research and theories. If those are inconclusive, what exactly do you expect the author to do about it?
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bmacho
Indeed. It is an uncomfortable read, and it avoids any factual or relevant information.
veunes
It's definitely not the clearest write-up but I cannot say that it's terrible...
rx_tx
H.I. Sutton did a great video [1] about it that also explains how it was beneficial due to the way enemy submarines had to estimate speed and heading and could get fooled.
Syonyk
When you're trying to hit something moving 20kt, with something moving 30-35kt, from a few thousand yards, it doesn't take much error in estimating speed, heading, or distance, to make them miss. It's honestly more remarkable that they hit at all in those conditions, even with a "spread" (shooting several along slightly different headings hoping one or two will hit).
leoc
Anyone with a copy of Silent Hunter 3 https://store.steampowered.com/app/15210/Silent_Hunter_III/ can experience this for themselves. Trying to estimate another ship's heading from a vantage point near sea level is maddening, even with the aid of a little recognition book which shows ships of that class at various relative headings, and as TFA says it's especially hard to tell the difference between perpendicular and near-perpendicular relative headings.
Mind you, this also explains why dazzle was a promising idea in the first place. Calculating Angle On Bow was already the hard part of ship-against-ship targeting, why not try to make it even harder?
jvanderbot
SH3 vets plotted relative positions to get heading much more reliably, which was something that was also insanely difficult for sub captains.
With some trig you can get relative headings by taking bearing measurements, waiting 30s, and then taking more, but speed must be known.
To get full heading and speed you can do the same thing multiple times but now we're in a least squares problem and it has plenty of singularities.
The most reliable method for me was to pass in front of the ship submerged the fire tail tubes or turn around if you have enough time.
Insanely difficult for fast moving targets.
I played so much SH games from the first days on, that I went and did my PhD on tracking using bearing measurements (albeit mostly applied and only a tiny theoretical contribution).
jaggederest
Well, at least in WW2 they had mechanical computers that could use the input width of the vessel and the class to estimate the range, heading, and firing angle to set the torpedoes up. There's a good series of youtube videos by a sim player that teaches how to use the TDC: https://www.youtube.com/watch?v=ANk6hZCcVRw - it's very in depth, and demonstrates how much effort it takes to get a firing solution, as you say.
leoc
The worst thing is that the TDC's calculation is very much GIGO if you get the Angle On Bow input wrong, and that's the hardest thing to get right.
veunes
Even with a spread, you're really just narrowing the odds, not guaranteeing a hit
cratermoon
Adding to the difficulty is the possibility of observers seeing the incoming torpedoes and a fast-moving, maneuverable ship dodging them. Fast and maneuverable as in .. the USS New Jersey, able to sidestep a spread of five torpedoes from a Japanese destroyer.
https://en.wikipedia.org/wiki/Japanese_destroyer_Maikaze#Con...
jabl
It's impossible to conclusively say whether dazzle worked or not, due to the large number of confounding variables. One study, which I unfortunately forget where I read it, came to the tentative conclusion that it was probably mostly a wash. Yes, dazzle helped somewhat and there was as a result a slightly lower percentage of successful attacks (that is, more torpedoes that missed their target), but OTOH due to being easier to spot in the first place the dazzle painted ships also invited more attacks.
veunes
Still, it's fascinating how much effort went into visual deception before radar and sonar changed the game entirely
noworld
It worked on me. I have yet to sink a single merchant ship in WW1.
me_me_me
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aaron695
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web007
Look up "CV dazzle" for the equivalent in the modern age, makeup effects to avoid facial detection / recognition.
vasco
By far the most common usage in the real world is in camouflaging prototype cars while being tested on the road https://www.bmw.com/en/automotive-life/prototype-cars.html
This way paparazzi can take pictures but it's hard to distinguish the shapes.
mattlondon
I think they also sometimes wrap polystyrene blocks under the camouflage too, so that particular curves on e.g. the wings or nose etc are altered by virtue of the camouflage having to confirm over that too.
Doxin
I was about to say, dazzle camouflage seems just about perfect for doing 3d scanning on, so many nice high contrast areas for measuring stereo disparity!
skhr0680
That's really interesting. The times I've seen Toyota street testing pre-release cars, they were not disguised whatsoever, and had unmissable "factory" number plates
Hamuko
I've seen Mercedes-Benz test their car in camouflage even though the car was already unveiled. I guess they didn't wanna go through the effort to unwrap it. They were also a long way from Germany (with German plates).
bsenftner
I'd say the most common usage in the real world is click-bait surveillance fear articles discussing CV-Dazzle and the entire surveillance state being erected. The theater around all this is as much "it" as the things themselves.
mrguyorama
Buddy Peter Thiel hangs out in the white house and provides Palentir services to law enforcement that they would not be allowed to do themselves without a warrant.
The surveillance state is here
mattclarkdotnet
The car manufacturers do this for the coverage (pun intended). It probably also feels cool if you are on the team.
gmueckl
I've seen plenty of these cars around Stuttgart and Munich. These patterns make it surprisingly hard to discern details in their shapes. Add to that the fact that early prototypes are deliberately padded to obscure their actual design and there's virtually no way to tell what the final production car will look like when you see these on the road.
MrBuddyCasino
You can see these cars (called "Erlkönig") all the time when driving near car manufacturer headquarters, and often also elsewhere on the Autobahn.
NackerHughes
I remember that when it first came out. I get it’s a theoretical or fashion type thing, but the concept seemed flagrantly absurd to me. Block automated facial recognition in a way that in turn makes your face instantly recognisable in any crowd…
glenstein
I've heard this as a reaction to the strategy before. "Now you're much more recognizable!" Well, yes and no. You're identifiable in the sense that you're unique among people in a crowd. But that equivocates between two different senses of identify. There's nothing actionable about looking at a person who looks different and saying "well they look different." That doesn't attach to any database or anything.
Meanwhile, positive facial identification attaches to all kinds of legal and intelligence infrastructure. Now, you can be charged with crimes, have a warrant executed against you, can be accused of supporting terrorists if you show up to a protest, etc.
I suppose I don't think the criticism is wrong, but it seems to presume that this is new information not previously understood rather than an intentional calculated risk.
cwmma
Especially at the time it came out, surveillance footage was mainly going to be reviewed by mark I eyeballs, so the inability for computers to notice where a face was is going to be way outweighed by the person being sooo much more recognizable to a human.
If you don't think there is a disadvantage to looking different in a protest, think about the "qanon shaman" from 1/6 him looking different totally made him more of a target to being identified.
genewitch
A hat with infrared LEDs aimed out, such that there was a torus of light around your face. Invisible to humans (generally), only visible to cameras.
It won't "work right" on cameras that have permanent IR filters. Maybe. I haven't tested this in years.
I have a feeling that IR of the correct strength and frequency would be dimly visible to humans, though. Similar to cameras with monochrome night vision via IR LED.
bsenftner
One only needs 1 or two LEDs near their face, but they need to be blinking in short irregular intervals. Cameras have mechanical controls for controlling focus and the amount of light they capture, and that can be attacked with these irregular blinky LEDs that cause the camera to try to adjust to the bright illumination from the LED, but then it is gone before the adjustment is complete, but then it is on again, then off again. The result is a person that never is more than a grey silhouette.
I worked in enterprise FR, on one of the globally leading systems, as the lead developer. That scenario defeats pretty much all FR when from a single camera. It can be mitigated with multiple camera views, which few FR systems are setup for multiple quality views at every key location.
TeMPOraL
That would only maybe work for automated tracking; if someone wants to get the image of your face, they should be able to do it in post, unless the recording quality is shitty - the tiny variations in brightness might contain just enough information to reconstruct the face shape with a little filtering.
(Now I wonder, how narrow-band such IR LED is, and if it could be made to emit a single frequency so sharp, it would create funny diffraction patterns off cameras' surfaces and lens imperfections, clobbering the high-frequency components of the image...)
bsenftner
And it is trained FR algorithm specific, so more than useless in the real world where one does not know what FR system is in use.
retSava
See also the "Berlin Brigade" urban camo: https://www.reddit.com/r/camouflage/comments/10qw7o9/urban_c...
One of my favorites. Haven't found much to read about it, so don't know how effective it was, or why it's not used more.
upofadown
Back in the day, it was considered prudent to repaint your pirate satellite TV to make it look less obvious. Knowing about the dazzle idea, I did bright white and dark black in rectangular blocks to break up the shape of the dish. After I was done and the dish was on the roof I realized I had reinvented a fairly conventional urban camo scheme. It was the same as used on the pictured tanks.
Afterwards I realized the weaknesses of such a scheme. Against an actual urban background it was quite effective in preventing perception of the oval shape of a satellite dish. Backlit by a bright sky, not so much. The oval shadow cast by the dish in sunlight was also quite easy to detect.
dingaling
It was very effective in the specific combination of urban landscape and shadows of Berlin. However the Brigade were only expected to fight there until being overrun by the NVA* ( East German Army ) so they didn't need to consider the camouflage's performance in rural areas.
All modern multi-terrain camouflage does incorporate some aspects of the Berlin pattern, particularly contrasting shadow.
* The NVA's commitment to wider WarPac strategy was questionable so the Brigade was intended to inflict both physical and philosophical damage upon them whilst fighting for their capital; once that objective was seized, it was hoped that the NVA would show little further interest in pushing westward. This was intended to reinforce the forecast reluctance of Czechoslovak and Polish forces and lead to the isolation of Soviet forces.
ionwake
my new fav camo after the sukhoi blue . nice. thx for sharing.
MisterTea
The fun part about this article is I did not know the term "razzle dazzle" came from this kind of camo. As in: "I gave em the ol razzle dazzle" meaning "I was able to escape being pursued." Even the first comment below mention the "old razzle dazzle." Fun term.
veunes
How many other accepted wartime "innovations" might have been misattributed
ggm
Diagrams would really have helped comprehension.
sidewndr46
I've looked for an academic explanation of this "horizon effect" but can't find anything. Most things I find seem to be related to AI somehow.
I don't really get how the horizon effect is something that could be confused/conflated with the effect of dazzle camouflage. The horizon effect is described as a predictable bias in angle estimation, relative to the true angle, when a ship is viewed such that it's near the horizon. This presumably always applies to the view from a periscope, so it would be ever present in any remotely reasonable test of dazzle camouflage (whether to a neutral control or to conventional camouflage patterns). They just say that Blodgett’s control was "too vague to be useful", but it would have to be a truly terrible control to lead to the suggested confusion, e.g., comparing dazzle camouflage through a periscope to conventional camouflage viewed from above.