as someone who grew up in the mountains can tell you they absolutely work when correctly implemented the problem comes with cars who have running lights you can't use other lights with fog lights it makes them completely ineffective 🎉
it's not some magical light that makes fog disappear it's just a lower intensity amber light to stop the glare off the fog which won't work if you have other lights on
I worked with Rallye car lighting a long while ago, and the fog lamps were almost never yellow... the most important thing was beam control, the elimination of "stray light" near the car, light which preferentially causes more glare to the driver... The very best fog lamps have tremendous control, with a very "flat top" beam, and extra shielding of the light source, and with careful design to eliminate stray reflections. I have, in fact, applied tape to the standard headlights on my car, to eliminate stray beams that come up out of the lamps. The European standard beam pattern for low beam headlights already has a sharp "cut-off" on the top of the beam pattern, to eliminate glare to oncoming traffic, but the headlights are not required to control stray light that doesn't affect other traffic. By checking your car's headlights in a garage, you can often spot the stray light that goes up and out, close to the car, and simply check with your hands where the beams come from, and put some appropriate tape just over those areas, without interfering with the Norma beam pattern
great demonstration! heres why I like to use yellow (or another color) "fog" lights (its not for fog). with two different colors of lights mounted in different places on front of the car, the road surface and any imperfections, or hazards cast shadows with two different colors making it stand out. its super helpful in whiteout snowy roads, where the ruts in the snow will have two distinct shadows. you get the same effect using a blue light with just regular halogens also. if it was street legal here id run two different colored headlights.
Headlight manufacturers hate him for this one weird trick… thank you guys for doing this. Your content is really to be taken as a good example of citizen science. All the best!
I always thought that the yellow fog lights are for you to be more visible, not the other way around. That is, during daylight fog, everything is white, so a yellow light might be noticeable slightly more than white. But I am not sure if it's true. Of course, for night time, only the height and beam pattern will make a difference.
Seems like slowing down in bad conditions is way more important than the foglights color. Although from your presentation I'd say I prefer white light.
Maybe since fog lights are much lower to the ground (at least on cars I've owned), less light is scattered back into the drivers eyes. Like the advice to not use hi-beams when in fog. While I've always liked the look of yellow fog lights, I've never bothered to purchase them.
I grew up in the mountains in a time cars didn't have running lights and you turn your headlight off when using fog lights which you can't do with modern cars and it's exactly for the reason you mentioned
Experiment setup was pretty good. The translation of light source when doing the A/B testing was sadly a bit unfortunate due to the source/angle of the light “moving”. I appreciated this video. To me - the white was best, the bright yellow secondary. Green seemed interesting (I know there’s a biological component to that). For my own thoughts - I have tried to take video or pictures of fog when driving before. Turns out my iPhone’s camera was cutting through the fog pretty good. IE: the screen was clear compared to the naked eye. I loathe the thought of “flying by camera” - but a secondary small screen might be interesting.
There's just no getting around the fact that there's no real difference in scattering coefficient vs wavelength (in the visible region, anyway) once you're out of the Rayleigh scattering regime and into the Mie scattering dominated regime. The only way to "null-out" scattering like this is with highly exotic time-reversal encoding stuff and there ain't no way that's coming to car headlamps any time soon. The underlying techniques are highly fascinating and promising for medical imaging though and I recommend the work of Lihong Wang and his photoacoustic tomography methods in anyone's interested. There are several very good lectures by him right here.
To me, white is the best because colored lights make the signs harder to read. Yellow signs fade into the fog with yellow light and the same with red signs and red light. Having the light coming from a larger area farther off-axis from the driver seems much more important. Light coming from a car-width bar mounted low on the bumper is less dazzling than the same light coming from a spotlight right next to the driver's head.
Fascinating! I had no idea these yellow fog lights were popular again. Last time I saw them often was like, late 90's early 00's? I'd think of there was any evidence of yellow working better in fog, they'd come standard. Cool stuff!
I really don't understand this, my understanding was that fog lights need to be mounted lower on the vehicle so that the light can light up the road and reach out further due to the fog usually sitting above the road due to the road being warmer than the atmosphere.... Therefore the light can reach further unimpeded by the fog. I'm sure that a lot of people who have driven through a fog and tried using their high beams and would have realised that it just lit up the fog even brighter and then quickly went back to the normal light beam, but if you had fog lights or spot lights that are mounted closer to the ground, you will find that this is where they shine.... This is what they were designed for.... Leave your parker lights on and turn on your fog/spot lights and you will see how much better it works...
yellow was so you don't blind yourself through reflection, having used them in real life they are a lot easier on the eyes, the French used to have them standard
19:23 The white gives more definition because objects can reflect colors back, which differ from the white the fog takes on. When everything is orange, including fog, objects can only stand out by being brighter. 21:17 This yellow light is better than the orange because it has other wavelengths, e.g. the green in the GO sign can be seen. But it's still not an improvement over white.
One difference in color rendering is that these LEDs have very "bandpass" (quasi monochromatic) spectra, compared to a "lowpass" incandescent light, which would give a bit better color differentiation.
The test is inconclusive: real world signs are retroreflective, test articles are not. Also there are noticeable specular reflections of the laminated test signs that favour one light bulb position over another. Another aspect is human eye response curve in the mesopic range. This is eliminated in this experiment by placing a camera and a phone or PC screen between the scene and the viewer (who is additionally in an uncontrolled illumination environment) I understand your limitations of a normal robot^W human being living a normal life and not being a scientific institution, but the experiment can be improved by: 1) reducing temporal backscatter fluctuation: maybe enclosing the test volume with a transparent front wall to limit fog loss, with test lamps placed inside, and cutting down on exhaust fan volumetric rate to establish steady state foggy conditions 2) increasing test arena size significantly (fill a barn with a rental fog machine) 3) using both diffuse targets (e.g. chalk, non-laminated office paper or even e-ink display) and proper retroreflective tape. 4) redesigning the experiment to measure response time of human test subjects to visual stimuli (possibly of different sizes, contrasts and reflectivity) appearing at random on the back of the fog chamber. The subjects should be adapted to mesopic (twilight) vision conditions. Reviewer 2 signing off.
Of course the white one is the best in the fog. I believe the traditional yellow headlight is not for the driver himself but the other people or other drivers at opposite direction. Because at that time that spectrum is far more unnatural than the incandescent lamps. Another major reason could be the fog lamp does actually prepare you for smoke and sand storm conditions. In those events you definitely see the sky turn yellow so it means high frequency visible light get absolved more. If you have been in CA for long time you should be very familiar with these conditions: wild fire, sand storms. I think the industry basically want to have a general solution.
Since my teenage years I would hear about how one color was best for fog. Then a few years later a different color was trending. Every few years the color would arbitrarily change. That’s a good indication that something is just a gimmick.
I love the jankiness of the setup 🤣 tbh, i have xenon + halogen fog lamp setup, and i can turn the both on individually and my conclusion is that the yellow light is easier for the eye in a dense fog and yellow light will keep your pupils more open. Pupils are triggered by green-blue light, and it's almost completely ignores the yellow-red lights. If you ever did skiing, you absolutely understand why yellow is better. Also coincidentally the eye has the best resolution in the green-yellow range, but horrible resolution in the red and blue spectrum
I installed a new type of florescent lights in our local court house to save on energy cost. The only bulbs available were what they call warm white, where they were accustomed to seeing daylight, which is more towards the blue. Everybody there hated them, because it made it more difficult to see. Most people are going to prefer white, not yellow.
There is a Selective Yellow article in Wikipedia about this topic. Wikipedia refers an old study from1970. Meanwhile yellow lights are forbidden in Europe for new cars, even in france and sweden. Did you test different light angles as well as the fog lamps are mounted closer to the street? Maybe reflection angle has some effect as well.
After many years of flight testing, I have learned that many tests lead to more questions. I drove along the coast of California in fog a lot. What I thought about was keeping the fog lights down low because many times the fog didn't quite reach the road. Is that perception or real? It would be good to see some tests. Also dimmer lights seemed to scatter less light into the fog but I'm not sure that made for better visibility. A real test would be interesting. And I like yellow lights so people can see me, but I'm not sure that's worth anything. I know I can't see well with yellow lights. Another possible interesting test. Thanks!
Sometimes I've used yellow glasses which helped me with contrast between dusk and night when driving. But I don't always feel the need to use them, so I think it could have to do with how tired I might feel. Obviously, if I use the yellow glasses when I don't need them they can be more of a distracting hindrance. Now for fog, definitely no yellow glasses or fog lights. White light can better differentiate colors.
What you need most is to be able to see the continuity of the road and for this reason the fog lights should be placed very low on the car's mask and also aim low & straight to the road surface. If they aim high and far the fog scattering will anyway blind/confuse your vision and it doesn't help to check the road. Also, fog lights should NOT be strong because in medium to low light conditions we can see more details (the pupil of the eye remains more open and more receptors are activated, also the peripheral vision,). My old SAAB came with strong factory xenon lights and also factory fog lights which are some old classic bulbs very low on the mask (warm white light, you know) and they DO work better on fog conditions, even alone.
The difference in light bulb position seemed to be on the same order of magnitude as the variations in fog density. This made it hard to judge the difference in viability when you switched from one light to the other. Some of the "signs" would seem clearer and some less clear depending on the relative location of the fog and the light that was on. I think getting rid of the commercial light housings, and just placing the bulbs close together might be a better way to do this test. Maybe make a rectangular tube for the lights out of the cheep material that you used for the fog tunnel -- possibly 30mm X 60mm by 300mm. With a black interior and the lights mounted at one end, this would eliminate much of the vertical and horizontal light scatter. Simulating a well focused beam pattern without the need for parabolic reflectors or lenses.
Is there any effect of the windshield angle? or different materials the windshield is made off. for example I find it that lights from lamps/cars at night shine extremely bright while I am driving my car while I am at my friends cars it isn't that's shiny, because the windshield angle has smaller angle of attack, so I am curios maybe the angle of the windshield can affect how good you can see different colors.
you are correct, there are lots of different factors that affect the ability of lights to penetrate fog, but I was aiming to isolate just the optical effects of the light and the fog. It then doesn't matter about the other factors, they just add or subtract from the baseline. What I mean is that if color A is better than color B, then changing other factors, color A will still give a better result than color B. So, things like height of the lamp, windshield variances, etc will all make a difference, but the baseline remains. Hope I explained that clearly, I'm still suffering from New Year fuzziness...
I don't know if it matters for this experiment, but that bulb housing looks more suitable for driving lights than fog lights. Still watching... White > Orange... White > Yellow... However I do have two other factors that perhaps should be considered at the regulatory level. The first is how does the picture change if you have a vehicle with fog lights approaching you. Does this change which color is best? Second, do the results change with the age of the driver, the condition of the windshield (i.e. new and clean vs 10 years and 200k miles later? Does it change if the incoming lights need to be cleaned? FWIW, I have used both yellow and white, and I have found that while yellow is not as good, fewer oncoming drivers flash their annoyance which allowed me to keep them on until we were just a second or two from passing. This even held when I increased the wattage from 55, to 100 and finally 135w. I was using large European manufactured fixtures with heavy glass lenses (yellow for most of my tests) and metal reflectors. I can't remember if they were Bosch or Hella. I worked at a body show, so I had a whole pile of cosmetically damaged fog lights. I did these tests in 1988. The bulbs were all Osram. I had also changed the 5x7 sealed beams out for some E-code fixtures from Hella with 85-100w Oshram bulbs. I wound up settling on 100w bulbs in yellow lenses (because the 135w bulbs got the glass so hot it would crack if it started raining) and creating a switching system that allowed me to use any combination of headlights and fog lights. I drove about 35k miles a year back then. Those E-code headlights were fine to oncoming drivers as long as they were scrupulously clean. If I got flashed and didn't have the brights on, I pulled over and cleaned them. That got me out of a ticket once. So what I picked after my experiment was yellow, but much brighter than the typical white fog light. At the same brightness, white is the winner.
Not sure whether this is a particular fault of my pair of eyes, but I noticed that I have a markedly lower visual acuity in blue light. Not necesarily scattering, could be chromatic aberation in the eye, or different density of the sensors on the retina. You can easily do the experiment: use any graphics software to make three identical lines of text, spaced vertically on a black background: one red only (R,G,B=xr,0,0), one green only (R,G,B=0,xg,0), and one blue only (R,G,B=0,0,xb). Try to set xr, xg, xb so, that they are of the same perceived brightness. Then, in a dark environment, move slowly away from the screen, and see which line is the first one to turn illegible.
Nice experiment, as always done diligently and interesting. Wen I grew up I spent a lot of time in France where the cars had yellow lights. I was then told that another reason was the less blinding effect on deer and rabbits and such. And therefore causes less accidents, And I do not know if this is correct but it sound reasonable, following your argument about eyes reacting to light. My compliment!
Whe I was younger some of my colleaugs where into car tuning. They liked thete yellow lamps because of the collour.We worked for a company that made these lamps(owned by the chinese now) so we knew what was what. I think the scientists all sayed that it more sbjective and does nothing that could be proofen. I liked the yellow lamps too because it is one of my favourite collours and it did match to the car I had back then! But when the fog was realy thick you could do what you wanted. At some point you had less that 50m visual range no matter what. That meant walking speed. At least I did not come across some miracle lamp that could beat realy thick fog.
I think the test needs to be done in a way that mimics the actual placing of the lamps: the fog lights are 20-30 cm above the road surface, and the driver's eyes around 120- 150cm. That makes a lot of difference in the reflectiion of light. While I don't think there will be any difference in regards to color, height should be taken into account. Also, someone mentioned the sign surfaces.
Snowboarding/ Goggles....night/ Cloudy or "foggy" conditions..... From personal experience I had a high quality set of snowboard goggle- I snowboarded alot, and having a fulltime job meant doing so in the night... having a pair of goggles that had a yellow lens was a god send. What they did was provide more contrast to the environment...once flat white ground and white sky being fog, now I could make out and see each roller. Made any object once white on white pop out and could make out the definitions....I can't remember exactly which goggle. But they were top shelf. And the lens specific for the condition I was riding- the lenses were easily interchangeable. I had clear lenses for clear days so to not have the harsh cold air hurt my eyes- these did nothing for those cloud covered days where you can't see past your nose.... the brand of the goggle was Anon and the lenses were almost just an elongated oval that clipped on and off...so my experience..is that yellow/ orange does help...but not to see more as in illuminate. But bring out definition/ contrast
All depends on how sensitive is a particular person to a certain spectrum and how their brain perceives it. Hence, there can never be a standard result. Having said so, majority of the white light LEDs are not high CRI. Maybe once we have a broad spectrum whilte LED with a light spectrum similar to the sun, the results/preferences would change drastically. A relatable example would be good OEM white headlamps vs the crappy aftermarket ones.
Experiment to approach myth of poorly constructed made up science contents online about light color, that part was good subject approach( those are huge issue in particularly aftermarket automotive lighting industry), but this experiment really didn't look conclusive, not representing how fog lamp and its color behave I must say. One of biggest issue I noticed is assumption of all bulb output same beam pattern. Having same photometric intensity at single random point is not equal to all lamp are tested at same output volume, when each bulb outputting completely different distribution character. Especially those poor quality LED bulb not only compatible with reflector designed for H3 filament, but even visually emission point has misalignment in all LED bulbs. In such short distance, LED bulb emission pattern inconsistency is even immense, there is 100% chance sensor position photometric intensity assignment proportion is very inconsistent from one bulb to other. Basically, photometric intensity measured at sensor is not representing overall output volume in same proportion, but hugely confusing calibration that way. Also, testing object to be inconsistent/unknown uneven surface level + specular reflective surface makes near field assessment very much subjective to ray enter angle.( as explained above, one of lamp shows consistent distribution pattern) Fog beam main target is road edge detection, much more diffused property. And then, spectrum sensitivity curve difference consideration is something needed to be added to assessment( of human eyes and whatever the camera sensor, and also BPX61) For fog lamp, valuable experiment to be driver view near field object recognition impression difference from commonly and correctly adopted F or F3 function fog optics, that has identically and natively assigned white or selective yellow emitter, not LED bulb ( they never replicate correct beam) at Average driver eye height 1.2m fog lamp mount height 0.6m aim maximum gradient 0.75D, gradient minimum 0.08 Within this projection mapping on the ground, how object recognition comfort changes depend on spectral balance of light source. This gradient aim equal to projection range as much as 46m. That's realistic fog evaluation shall be. There is reason why fog lamp has regulated gradient minimum and very specific photometric distribution requirement. Beam pattern ( gradient control), lamp mount height and illuminance intensity is far more important than anything else in fog situation. Vast majority of the time, "yellow" light source are typically dimmer than "white" light source being used in fog lamp, user simply seeing less intense light compare to white, feeling more comfort because it is not as intense as white. Another reason why yellow fog became a thing is, seeing different color than main beam gives some kind of phycological reward? or justification of " I did something" projecting white light onto road surface simply feedback at illumination level, but with yellow light, seeing some other element, color, that gives, oh yes I am seeing something. Not knowingly less illumination potency than white. They think seeing better because actually seeing actually less volume of light, but at the same time compensating lower illuminance with that colored impression phycological boost. as a result, feel more comfortable with yellow in fog. In that context, yes yellow likely could be perceived better in fog, just not in the reason of most of those made-up science explanation video you linked. Another resolution may be added to is type of optical system difference behavior. Reflectors may not be so much of difference, but not too few modern fog optics are now refractive beam control, result in pretty harsh chromatic aberration even at optics level, especially with LED light source. Lamp must be compact/low cost enough, light weighted, really not much space to correct, blends it other than smudge bit with very faint diffusion that won't compromise G-max value . So this already is creating slightly yet certain different gradient variance, isolated shorter wave length blue band is more frequently observed from refractive optics. Some of sample can show this as much as 0.25 degree above intended gradient ( which can be prevented by careful optical design, but many optics won't receive such consideration much, sometimes, aftermarket community even think that isolated blue color as exotic feature or something... ) that we can easily see such difference even at fog beam projection range. In this case, image gradient projection definition wise, less blue containing selective yellow light source is much easier to create better projection definition.
Getting a +150W RGBW movie lamp and doing these experiments in actual foggy conditions testing with a few far off signs would be a pretty cool thing. The movie lamps have an ability to attach shades, fresnel lenses, reflectors, etc and they also run on batteries / dc power. I wonder if there would be a distance component?
I don't feel comfortable judging the representation of the road hazards in dark/fog conditions on screen, because i have no way of knowing whether that would correspond to real-life experience. I did try yellow eye lenses for cycling at dusk and while they seemed to do something to improve adaptation and make the path more legible, it's difficult to say whether they really did.
My general experience over a few decades of riding motorbikes in some exceptionally crappy weather is that I find white light tending very slightly towards blue preferable, and warm biased light downright awful. In terms of visual processing what I find here is that under warm/monotone light the only que you have to go on is shape perception - without any colour ques it is hard to discern real objects from billowing fog, and shadows. When broad spectrum light is used it is far easier to pick out shiney, man made, and coloured objects from the general noise in front of you. Also, bonus point - I rather like xenon lamps over everything else for one curious side effect, despite some half baked efforts to filter out the UV, a large quantity of it is still emitted, this makes 'day glow' style paints light up unnaturally bright at night, and also whatever the British make their road signs, cats eyes, and road paint, and license plates out of chuck light back at you to a crazy extent. you might not be able to see anything else more than a few tens of feet in front you, but you'll see that stuff bouncing back at you thru it for hundreds of yards just fine. also another thing to keep in mind with xenon lamps is most of the light in the plasma discharge is emitted as a thin band in the middle of the beam, so it is possible to achieve a very narrow peak intensity angle, and when that is reflected back at you, the scattering potential is greatly reduced.
Looks like the yellow halogen bulb did not emit a 'Selective Yellow' color based on the x, y coordinates. Didn't see what the measured yellow LED coordinates were. Selective Yellow is the color permitted for fog lamps besides white (UNECE R48 and SAE J578). Not sure this would have made much of a difference in the experiment though. The simulated fog moved too much around like a vapor which is not how fog behaves in a real world environment. Something else also to consider is that legitimate fog lamps designed in accordance to ECE/SAE standards would never illuminate road signage. I realize that the experiment needed visual targets inside the box but in the real world, signs should not be visibly lit by fog beams (unless the vehicle has lamps that call themselves fog lamps but aren't really fog lamps). These beams have a sharp cutoff and produce a wide, thin-like beam that produces short range illumination. They are meant to light the foreground and the sides of the roads to maintain lane keeping at slow speeds. They are not designed to reach far or act like low beams. Regarding the effectiveness of a selective yellow color compared to white, I believe more testing and research are needed to draw any meaningful conclusions.
Since the fog density is not homogenous because of its movement, would it be possible to make a sort of "temporal average" of a specific amount of pictures (don't know maybe 10, maybe 100 pictures)? I think It would be easier to make a comparison between the different colours/sources.
I grew up with the belief that fog lamps were for the oncoming drivers benefit more so than the operator. If you're ever in a foggy area where there are stoplights, simply look to see what color you can detect at what distance. red is the shortest wavelength, you have to be rather close to it. Yellow not so much and green goes way back there!
Not overly useful for fog lamps but you have fog and a multicolor LED. I've seen some studies that say green light will burn off fog better than other colors . It'd be interesting to pass a green laser through your red laser that's triggering the photo diode.. Not hitting the diode with the green laser but seeing if you can measure a difference in the fog with it and the response time it takes if any to see the difference if you happen to have an oscilloscope with a trigger. Another red & a blue laser would make for good tests to see which wavelengths are best. As for the experiment though polarizing filters on the lights & the camera tested at different angles might be an interesting "spin" on it. Photographers use that to cut through fog and in a vehicle you could get some polarizing glasses and control both the light and the view and it might cancel most of the light that's scattered and unpolarized in the fog while what makes it to the sign and reflects back in phase appears amplified.
Growing up in Europe in the 70s and 80s, I often wonder why the switch from yellow to white lights on vehicles, I never thought this had anything to do with fog but unlike you, I never pushed the thought further! I would've tried green light since the human eye is also sensitive in that region, but then again, we bump against the same conundrum of sensitivity vs accuracy dilemma.. based on your test, I did not see a major difference between the colors. The car salesman made me laugh though!!! 😂 Another great video sir! How close are you from getting a camera and what model do you have in mind?
It is interesting that automotive manufacturers (who have the most to lose financially if there is ever a safety issue that results in recall), use white lamps as standard. In Germany, anything other than white is illegal. I always assumed that yellow lamps in France was just to help the French traffic cops to easily identify tourists, so they could hand out traffic fines... I'm looking at used camera options to reduce the time it takes to get to a decent camera solution. Maybe a couple of months from being able to do that... I'm looking at something from the Sony Alpha 7 series for now.
You want to heat the bed of the test chamber and you need less turbulence in the fog, you also need to get a narrow but wide light beam as close to the bed.... Shining any light at eye level into a fog is going to impare your vision.... You want the ground lit up so that you can see it through the fog .....
Your video was nicely done... and the experiment was set up and documented really well... HOWEVER... it's NOT just a matter of dynamic range... It is widely accepted that THE HUMAN EYE has much better resolving power in the green range and rather poor resolution in the blue range... This is why, on a typical DVD, which stores the image in RGB, the three colors are NOT allocated equal bandwidth... The green image plane is stored at "full sharpness"... (Because the green image is what contributes most to our ability to see details and perceive sharpness.) While the blue image plane is stored at much lower resolution (HALF of the green resolution)... (The blue image is really not sharp at all but we simply don't notice it because we are "less sensitive to blue sharpness"...) (If you actually separate the colors in editing software you will see that the blue image is VERY fuzzy... but we simply don't notice.) "Yellow glasses" improve visibility, and make what we see seem sharper, because they cut out the blue part of the spectrum... By preventing the blue light from reaching our eyes, we see a slightly darker image, but with a higher percentage of yellow and green... It is OUR EYES that work better in the yellow and green wavelength ranges and less well in the blue ones... (As I understand it, the lenses in our eyes focus less sharply in the blue range, and we also have more sensors for the green/yellow range.) Therefore the purpose of yellow fog lights is basically the same as using yellow driving glasses... BUT THIS MEANS THAT YELLOW FOG LIGHTS WILL ONLY HELP SIGNIFICANTLY IF THEY ARE THE *ONLY* SOURCE OF LIGHT. This means that they work well on a dark road in the woods at night with your "whites" off... But don't work well at all if there is OTHER white light around (like streetlights). And, in fact, if you drive into a lighted area, or oncoming headlights, after using yellows, the glare will be worse. So you're probably better off using an effective pair of "blue blocker" driving glasses if it's foggy. So, yes, in an otherwise dark area, you will have better "black and white visibility" with something like yellow sodium lamps than with white light... But you will LOSE most color information. As your video also pointed out... many modern signs use color as part of their signaling (like bright red stop signs)... So things like Stop signs will be LESS visible under yellow light.
In Germany fog lamps in yellow are forbidden. French move over from yellow driving ligth to white. More important is the high over ground if the fog ligth. All other is culture. With your yellow ligth everbody in traffic know than we have fog..
I used to put fog lights on all my vehicles because I lived on the northern end of California's central valley and the fog could be so bad that I would have to follow the curb on my own street to get home (dodging parked cars). I knew that fog lights have to be mounted as low as you can get them to get under the layer of fog and not just blind you with reflected light. But then one day I thought "Why doesn't the CHP use fog lights if they actually work well?" and I stopped putting them on my vehicles.
you can download a 3rd party application that can give you total manual controls over cellphone cameras, many are free like black magic idea is that monochromatic or less wide range light helps you focus on features rather than content, so more vision power goes to analyze less information thus giving your brain better response times and thus better visibility, think how its easier to read a word on a clean white piece of paper rather than the word being written on a picture
This video needs the Radiacode 103, not the 103G, and the unicorn Geiger taken to 10km, and then a discussion of the difference between readings… Then bring on the multi color Christmas lights!
Despite the test result..... I think you still need to promote yellow light.. My argument..... Yellow light are causing less temporary blindness to eyes in the opposite direction since we are not the only one who use the roads..
Just looking at street signs, the white is best. What about normal surroundings other than signage, like trees or the road surface. Low angle vs. High angle, etc.
I think your color test is flawed. I thought at first that the white light was better but now i think it's because of how glare works and how the light propagates from the position it's in. I also think the signs you made should be more diffuse to prevent glare. you could treat the surface with 10 000 grit sand paper (yes that's ten thousand grit) to get the right effect for an object that small. Given the tiny geometry of the test, the position of hte light makes a big difference, but it changes between the lights. What you should have done is added a jig where the lights slide into the same place and only once they're in place they turn on. this could be done by putting both lights in a fixture that holds them together and then putting the whole thing on rails, kind of like a train car on rails, sliding horizontally left and right. The light that's in place touches contacts that run the light. meanwhile you can edit out the frames where you're transitioning the lights so there's no confusing flashing. Even though as you say in normal life fog will not be homogenous, there's two things to say: 1. Empirically, it will be homogenous to a large extent. I've never experienced fog irl that has such huge variation and visible vortices as your artificial fog, and I almost want to say it is always completely uniform. 2. Your fog moves around very fast, so when you're alternating lights, by the time you've switched the light the fog will have moved and the comparison isn't fair between both lights. To fix that maybe you could create a bunch of fog and use some sort of internal "mixing" fan to homogenize the fog. To help prevent the fog from falling out of the box, you could stand it upright so that the open wall is at the top. Also another thought: are you controlling the intensity of the LEDs with PWM? I wonder if bright pulses of light in PWM are somehow registered by differently our eyes than a continuous light without PWM, assuming both would average to the same amount. If you want to use an incandescent light and change its intensity without changing its temperature, use a normal filter over the reflector's front. It can be as easy as wrapping the filter in some gray translucent foil like used for christmas present wrapping or for adding tint to windows, but you might have to experiment a bit to find the right attenuation and to check the effect on the spectrum. You might want several layers of different attenuation and combine them kind of like a DAC's bits to build up the value you want.
The mix of cells in one person's retina are different from everyone else's. This is going to be a subjective choice after your debunking of common assumptions.😊
Today's modern LED and xenon based lights are far more effective when 'white'. That has been proven, including by your interesting experiment. Notice that 'white light' generally means a light source representing nearly the full visible light spectrum while yellow light reduced the spectrum that is used. Although, it is still my impression that back in the day ('70 and '80) when incandescent lights had much less light intensity than what we have today and when the orange colored sodium street lights were still the norm, those yellow beams where much more effective to brighten up the obstacles of your path. I guess the 'yellow' aficionados are stuck in the past.
Have you taken into account that a large percentage of the population wear corrective eyeglasses? Different wavelengths of light reach certain parts of the lenses at different times leading to distortion and glare. Please look into the Duchrome test, also known as the Bichrome test, performed by optometrists. White light contains multiple wavelengths which converge at different points in the eye possibly leading to blurriness or depth perception issues, but with yellow light the eye has less to process. I don't fully understand the process but have quite strong prescription eyeglasses (-5.5, -6) and astigmatism, and enjoy driving my older vehicles with older yellow 3000K halogen lights but hate driving my newer vehicle with white 6000K lights. I cannot see clearly with the white lights and driving at night is an unpleasant chore. However I don't suffer the same issues when switching back to the older vehicles with the yellow lights. I also struggle with the new trend toward thin line turn signals, where the amber line appears to float around in relation to the car, depending on the angle of my head while looking through eye glasses. If the thin line happens to float in front of the headlight at night or near a reflection off the edge of the car from sunlight during the day, it will be invisible to be. It's a dangerous distraction that is extremely common amongst drivers I've mentioned the issue to, yet rarely discussed. This issue simply is not present on older cars with square or rectangular turn signal lenses. Clear turn signal lenses make the issue far worse because instead of a large illuminated amber surface, people are expected to perceive 1cm square LEDs buried deep inside the housing (adding parallax error) while trying to figure out if the tiny dot of light is from the turn signal or a reflection from the sun or other nearby bright objects.
yeah people with astigmatic vision tend to like warmer lighting better, as do I, but I think this is more due to modern cool white LEDs tend to have ~120 degree light cast with very sharp luminosity dropoff at the edges, which aggravates the 'starburst' effect astigmatism causes. halogen & incancescent lighting in general cast their light in all directions, with a very soft luminosity dropoff instead, which likely leads to less eye strain. 'warm' LEDs also tend to have very thick phosphor coatings, at least compared to 'cool' ones, that mask the sharp casting pattern of the bare blue LED die by reradiating light past 120 degrees. I noticed high CRI LEDs of all color temperatures also tend to give me less eye strain, also likely due to very thick phosphor coatings, inferred from the lower effective luminosity per watt.
as someone who grew up in the mountains can tell you they absolutely work when correctly implemented the problem comes with cars who have running lights you can't use other lights with fog lights it makes them completely ineffective 🎉
Yellow lamps are almost universally used to indicate a hazard, so whether there is any scientific reason for their use is rather moot. Yellow lights psychologically indicate danger like red lights mean stop and green lights means go. Blue lights are reserved for emergency vehicles, so go figure. I have a pair of extremely expensive Zeiss glasses intended for flying an aircraft. These have a green tint to look at but are entirely neutral and don’t change the perceived colours when wearing them. What they do allow is better vision through fog, mist and haze, which is important when flying. The exact method used to filter scattered light is probably a trade secret, but they do work and allow you to see probably twice as far as with unaided vision. The lenses are not polarised because this would interfere with viewing LCDs in the cockpit, so some other method of filtering must be being used. I surmise a series of narrow band filter coatings sequentially applied to the lens to allow normal colour vision. Whatever process is used, it must be time consuming and expensive to justify the cost of the glasses.
Chromatic aberration likely causes issues for some people driving while wearing corrective eyeglasses. From Wikipedia: 'chromatic aberration, also called chromatic distortion, color aberration, color fringing, or purple fringing, is a failure of a lens to focus all colors to the same point.' People suffering from certain common eye conditions might genuinely perceive while light consisting of multiple colours as more distorted than a single colour of light. More than 50% of the population wears or will require eyeglasses at some point in their life, so this is something that should not be ignored.
Unlikely, very unlikely. Why would it be an impediment in fog in particular rather than for all driving or indeed all activities? It's also the reason i don't really like polycarbonate and trivex corrective lenses. Some people get used to colour fringing and stop perceiving it; but CR-39 is what the cheapest lenses are made from and it's effectively free of the issue. I've got cyl -6d on one eye which is a little spicy as in many manufacturers plain refuse to manufacture such a lens.
If you are typing "Rayleigh Scattering" right now, perhaps watch the video first...
as someone who grew up in the mountains can tell you they absolutely work when correctly implemented
the problem comes with cars who have running lights
you can't use other lights with fog lights it makes them completely ineffective
🎉
it's not some magical light that makes fog disappear
it's just a lower intensity amber light to stop the glare off the fog
which won't work if you have other lights on
By the way, I didn't find that community link on your channel.
if I still lived in the mountains with a modern car I'd invest in some headlight covers to put on when conditions got bad
Did you say "Robo-scattering"?
I worked with Rallye car lighting a long while ago, and the fog lamps were almost never yellow... the most important thing was beam control, the elimination of "stray light" near the car, light which preferentially causes more glare to the driver... The very best fog lamps have tremendous control, with a very "flat top" beam, and extra shielding of the light source, and with careful design to eliminate stray reflections.
I have, in fact, applied tape to the standard headlights on my car, to eliminate stray beams that come up out of the lamps. The European standard beam pattern for low beam headlights already has a sharp "cut-off" on the top of the beam pattern, to eliminate glare to oncoming traffic, but the headlights are not required to control stray light that doesn't affect other traffic.
By checking your car's headlights in a garage, you can often spot the stray light that goes up and out, close to the car, and simply check with your hands where the beams come from, and put some appropriate tape just over those areas, without interfering with the Norma beam pattern
That makes perfect sense.
great demonstration!
heres why I like to use yellow (or another color) "fog" lights (its not for fog). with two different colors of lights mounted in different places on front of the car, the road surface and any imperfections, or hazards cast shadows with two different colors making it stand out. its super helpful in whiteout snowy roads, where the ruts in the snow will have two distinct shadows. you get the same effect using a blue light with just regular halogens also. if it was street legal here id run two different colored headlights.
Headlight manufacturers hate him for this one weird trick… thank you guys for doing this. Your content is really to be taken as a good example of citizen science. All the best!
Thank you, it means a lot!
I always thought that the yellow fog lights are for you to be more visible, not the other way around.
That is, during daylight fog, everything is white, so a yellow light might be noticeable slightly more than white. But I am not sure if it's true.
Of course, for night time, only the height and beam pattern will make a difference.
Supporting Project 326 to find out.....
thank you!
hero
Thanks!
Welcome!
Seems like slowing down in bad conditions is way more important than the foglights color. Although from your presentation I'd say I prefer white light.
Great point, and here's another idea: stay home if it's an option.
Maybe since fog lights are much lower to the ground (at least on cars I've owned), less light is scattered back into the drivers eyes.
Like the advice to not use hi-beams when in fog.
While I've always liked the look of yellow fog lights, I've never bothered to purchase them.
I grew up in the mountains in a time cars didn't have running lights and you turn your headlight off when using fog lights which you can't do with modern cars
and it's exactly for the reason you mentioned
and even still most times it is so thick up there a few feet was the best you could hope for
remember times it would take a hour to go a mile
fog lamps also usually have a wider beam...maybe this helps with the dynamic contrast between the front and sides of the view angle?
Experiment setup was pretty good. The translation of light source when doing the A/B testing was sadly a bit unfortunate due to the source/angle of the light “moving”.
I appreciated this video. To me - the white was best, the bright yellow secondary. Green seemed interesting (I know there’s a biological component to that).
For my own thoughts - I have tried to take video or pictures of fog when driving before. Turns out my iPhone’s camera was cutting through the fog pretty good. IE: the screen was clear compared to the naked eye. I loathe the thought of “flying by camera” - but a secondary small screen might be interesting.
There's just no getting around the fact that there's no real difference in scattering coefficient vs wavelength (in the visible region, anyway) once you're out of the Rayleigh scattering regime and into the Mie scattering dominated regime. The only way to "null-out" scattering like this is with highly exotic time-reversal encoding stuff and there ain't no way that's coming to car headlamps any time soon. The underlying techniques are highly fascinating and promising for medical imaging though and I recommend the work of Lihong Wang and his photoacoustic tomography methods in anyone's interested. There are several very good lectures by him right here.
To me, white is the best because colored lights make the signs harder to read. Yellow signs fade into the fog with yellow light and the same with red signs and red light.
Having the light coming from a larger area farther off-axis from the driver seems much more important. Light coming from a car-width bar mounted low on the bumper is less dazzling than the same light coming from a spotlight right next to the driver's head.
Fascinating! I had no idea these yellow fog lights were popular again. Last time I saw them often was like, late 90's early 00's?
I'd think of there was any evidence of yellow working better in fog, they'd come standard. Cool stuff!
Yes, you are correct, there is a reason that they are illegal in Germany and car manufacturers don't sell cars with them as standard...
I really don't understand this, my understanding was that fog lights need to be mounted lower on the vehicle so that the light can light up the road and reach out further due to the fog usually sitting above the road due to the road being warmer than the atmosphere.... Therefore the light can reach further unimpeded by the fog.
I'm sure that a lot of people who have driven through a fog and tried using their high beams and would have realised that it just lit up the fog even brighter and then quickly went back to the normal light beam, but if you had fog lights or spot lights that are mounted closer to the ground, you will find that this is where they shine.... This is what they were designed for.... Leave your parker lights on and turn on your fog/spot lights and you will see how much better it works...
Correct
yellow was so you don't blind yourself through reflection, having used them in real life they are a lot easier on the eyes, the French used to have them standard
19:23 The white gives more definition because objects can reflect colors back, which differ from the white the fog takes on. When everything is orange, including fog, objects can only stand out by being brighter.
21:17 This yellow light is better than the orange because it has other wavelengths, e.g. the green in the GO sign can be seen. But it's still not an improvement over white.
One difference in color rendering is that these LEDs have very "bandpass" (quasi monochromatic) spectra, compared to a "lowpass" incandescent light, which would give a bit better color differentiation.
The test is inconclusive: real world signs are retroreflective, test articles are not. Also there are noticeable specular reflections of the laminated test signs that favour one light bulb position over another.
Another aspect is human eye response curve in the mesopic range. This is eliminated in this experiment by placing a camera and a phone or PC screen between the scene and the viewer (who is additionally in an uncontrolled illumination environment)
I understand your limitations of a normal robot^W human being living a normal life and not being a scientific institution, but the experiment can be improved by:
1) reducing temporal backscatter fluctuation: maybe enclosing the test volume with a transparent front wall to limit fog loss, with test lamps placed inside, and cutting down on exhaust fan volumetric rate to establish steady state foggy conditions
2) increasing test arena size significantly (fill a barn with a rental fog machine)
3) using both diffuse targets (e.g. chalk, non-laminated office paper or even e-ink display) and proper retroreflective tape.
4) redesigning the experiment to measure response time of human test subjects to visual stimuli (possibly of different sizes, contrasts and reflectivity) appearing at random on the back of the fog chamber. The subjects should be adapted to mesopic (twilight) vision conditions.
Reviewer 2 signing off.
Of course the white one is the best in the fog. I believe the traditional yellow headlight is not for the driver himself but the other people or other drivers at opposite direction. Because at that time that spectrum is far more unnatural than the incandescent lamps. Another major reason could be the fog lamp does actually prepare you for smoke and sand storm conditions. In those events you definitely see the sky turn yellow so it means high frequency visible light get absolved more. If you have been in CA for long time you should be very familiar with these conditions: wild fire, sand storms. I think the industry basically want to have a general solution.
Green was interesting. Actually seemed to help😯
The best thing I’ve found to do in fog is to use my low beams. The done illuminate the fog in line with the windshield like high beams do.
Since my teenage years I would hear about how one color was best for fog. Then a few years later a different color was trending. Every few years the color would arbitrarily change. That’s a good indication that something is just a gimmick.
I tried this with more recent smarter AI and it nailed it and discussed the same misconceptions.
I love the jankiness of the setup 🤣 tbh, i have xenon + halogen fog lamp setup, and i can turn the both on individually and my conclusion is that the yellow light is easier for the eye in a dense fog and yellow light will keep your pupils more open. Pupils are triggered by green-blue light, and it's almost completely ignores the yellow-red lights. If you ever did skiing, you absolutely understand why yellow is better. Also coincidentally the eye has the best resolution in the green-yellow range, but horrible resolution in the red and blue spectrum
I installed a new type of florescent lights in our local court house to save on energy cost. The only bulbs available were what they call warm white, where they were accustomed to seeing daylight, which is more towards the blue. Everybody there hated them, because it made it more difficult to see. Most people are going to prefer white, not yellow.
Interesting point about the color temperature affecting visibility!
O canal apareceu como sugestão, sou do Brasil e curti demais o conteúdo, ganhou um inscrito
There is a Selective Yellow article in Wikipedia about this topic. Wikipedia refers an old study from1970.
Meanwhile yellow lights are forbidden in Europe for new cars, even in france and sweden.
Did you test different light angles as well as the fog lamps are mounted closer to the street? Maybe reflection angle has some effect as well.
The problem with yellow fog lights is they're made overly bright and blind oncoming traffic instead of a reasonable bright yellow light
After many years of flight testing, I have learned that many tests lead to more questions. I drove along the coast of California in fog a lot. What I thought about was keeping the fog lights down low because many times the fog didn't quite reach the road. Is that perception or real? It would be good to see some tests. Also dimmer lights seemed to scatter less light into the fog but I'm not sure that made for better visibility. A real test would be interesting. And I like yellow lights so people can see me, but I'm not sure that's worth anything. I know I can't see well with yellow lights. Another possible interesting test. Thanks!
Importantly fog-lights work best when bounced off the road
Sometimes I've used yellow glasses which helped me with contrast between dusk and night when driving. But I don't always feel the need to use them, so I think it could have to do with how tired I might feel. Obviously, if I use the yellow glasses when I don't need them they can be more of a distracting hindrance. Now for fog, definitely no yellow glasses or fog lights. White light can better differentiate colors.
What you need most is to be able to see the continuity of the road and for this reason the fog lights should be placed very low on the car's mask and also aim low & straight to the road surface. If they aim high and far the fog scattering will anyway blind/confuse your vision and it doesn't help to check the road. Also, fog lights should NOT be strong because in medium to low light conditions we can see more details (the pupil of the eye remains more open and more receptors are activated, also the peripheral vision,). My old SAAB came with strong factory xenon lights and also factory fog lights which are some old classic bulbs very low on the mask (warm white light, you know) and they DO work better on fog conditions, even alone.
The white light gives unquestionably the best visibility of all signs and road hazards.
The difference in light bulb position seemed to be on the same order of magnitude as the variations in fog density. This made it hard to judge the difference in viability when you switched from one light to the other. Some of the "signs" would seem clearer and some less clear depending on the relative location of the fog and the light that was on. I think getting rid of the commercial light housings, and just placing the bulbs close together might be a better way to do this test. Maybe make a rectangular tube for the lights out of the cheep material that you used for the fog tunnel -- possibly 30mm X 60mm by 300mm. With a black interior and the lights mounted at one end, this would eliminate much of the vertical and horizontal light scatter. Simulating a well focused beam pattern without the need for parabolic reflectors or lenses.
Is there any effect of the windshield angle? or different materials the windshield is made off.
for example I find it that lights from lamps/cars at night shine extremely bright while I am driving my car while I am at my friends cars it isn't that's shiny, because the windshield angle has smaller angle of attack, so I am curios maybe the angle of the windshield can affect how good you can see different colors.
you are correct, there are lots of different factors that affect the ability of lights to penetrate fog, but I was aiming to isolate just the optical effects of the light and the fog. It then doesn't matter about the other factors, they just add or subtract from the baseline. What I mean is that if color A is better than color B, then changing other factors, color A will still give a better result than color B.
So, things like height of the lamp, windshield variances, etc will all make a difference, but the baseline remains. Hope I explained that clearly, I'm still suffering from New Year fuzziness...
Definitely the white light for me, I don't like the way all the colour on the signs vanishes under the yellowed conditions
I don't know if it matters for this experiment, but that bulb housing looks more suitable for driving lights than fog lights. Still watching... White > Orange... White > Yellow... However I do have two other factors that perhaps should be considered at the regulatory level. The first is how does the picture change if you have a vehicle with fog lights approaching you. Does this change which color is best? Second, do the results change with the age of the driver, the condition of the windshield (i.e. new and clean vs 10 years and 200k miles later? Does it change if the incoming lights need to be cleaned? FWIW, I have used both yellow and white, and I have found that while yellow is not as good, fewer oncoming drivers flash their annoyance which allowed me to keep them on until we were just a second or two from passing. This even held when I increased the wattage from 55, to 100 and finally 135w. I was using large European manufactured fixtures with heavy glass lenses (yellow for most of my tests) and metal reflectors. I can't remember if they were Bosch or Hella. I worked at a body show, so I had a whole pile of cosmetically damaged fog lights. I did these tests in 1988. The bulbs were all Osram. I had also changed the 5x7 sealed beams out for some E-code fixtures from Hella with 85-100w Oshram bulbs. I wound up settling on 100w bulbs in yellow lenses (because the 135w bulbs got the glass so hot it would crack if it started raining) and creating a switching system that allowed me to use any combination of headlights and fog lights. I drove about 35k miles a year back then. Those E-code headlights were fine to oncoming drivers as long as they were scrupulously clean. If I got flashed and didn't have the brights on, I pulled over and cleaned them. That got me out of a ticket once. So what I picked after my experiment was yellow, but much brighter than the typical white fog light. At the same brightness, white is the winner.
Not sure whether this is a particular fault of my pair of eyes, but I noticed that I have a markedly lower visual acuity in blue light. Not necesarily scattering, could be chromatic aberation in the eye, or different density of the sensors on the retina.
You can easily do the experiment: use any graphics software to make three identical lines of text, spaced vertically on a black background: one red only (R,G,B=xr,0,0), one green only (R,G,B=0,xg,0), and one blue only (R,G,B=0,0,xb). Try to set xr, xg, xb so, that they are of the same perceived brightness. Then, in a dark environment, move slowly away from the screen, and see which line is the first one to turn illegible.
Nice experiment, as always done diligently and interesting. Wen I grew up I spent a lot of time in France where the cars had yellow lights. I was then told that another reason was the less blinding effect on deer and rabbits and such. And therefore causes less accidents, And I do not know if this is correct but it sound reasonable, following your argument about eyes reacting to light. My compliment!
Whe I was younger some of my colleaugs where into car tuning. They liked thete yellow lamps because of the collour.We worked for a company that made these lamps(owned by the chinese now) so we knew what was what. I think the scientists all sayed that it more sbjective and does nothing that could be proofen.
I liked the yellow lamps too because it is one of my favourite collours and it did match to the car I had back then! But when the fog was realy thick you could do what you wanted. At some point you had less that 50m visual range no matter what. That meant walking speed. At least I did not come across some miracle lamp that could beat realy thick fog.
I think the test needs to be done in a way that mimics the actual placing of the lamps: the fog lights are 20-30 cm above the road surface, and the driver's eyes around 120- 150cm. That makes a lot of difference in the reflectiion of light. While I don't think there will be any difference in regards to color, height should be taken into account. Also, someone mentioned the sign surfaces.
Enjoyable video. Please don't make shorts.
Great topic! Keep up the good work.
Thank you, I appreciate the feedback!
Snowboarding/ Goggles....night/ Cloudy or "foggy" conditions..... From personal experience I had a high quality set of snowboard goggle- I snowboarded alot, and having a fulltime job meant doing so in the night... having a pair of goggles that had a yellow lens was a god send. What they did was provide more contrast to the environment...once flat white ground and white sky being fog, now I could make out and see each roller. Made any object once white on white pop out and could make out the definitions....I can't remember exactly which goggle. But they were top shelf. And the lens specific for the condition I was riding- the lenses were easily interchangeable. I had clear lenses for clear days so to not have the harsh cold air hurt my eyes- these did nothing for those cloud covered days where you can't see past your nose.... the brand of the goggle was Anon and the lenses were almost just an elongated oval that clipped on and off...so my experience..is that yellow/ orange does help...but not to see more as in illuminate. But bring out definition/ contrast
All depends on how sensitive is a particular person to a certain spectrum and how their brain perceives it.
Hence, there can never be a standard result.
Having said so, majority of the white light LEDs are not high CRI.
Maybe once we have a broad spectrum whilte LED with a light spectrum similar to the sun, the results/preferences would change drastically.
A relatable example would be good OEM white headlamps vs the crappy aftermarket ones.
" All depends on how sensitive is a particular person to a certain spectrum "
Carefull there are a lot of sensitive people that are on the spectrum.
Experiment to approach myth of poorly constructed made up science contents online about light color, that part was good subject approach( those are huge issue in particularly aftermarket automotive lighting industry), but this experiment really didn't look conclusive, not representing how fog lamp and its color behave I must say. One of biggest issue I noticed is assumption of all bulb output same beam pattern. Having same photometric intensity at single random point is not equal to all lamp are tested at same output volume, when each bulb outputting completely different distribution character. Especially those poor quality LED bulb not only compatible with reflector designed for H3 filament, but even visually emission point has misalignment in all LED bulbs. In such short distance, LED bulb emission pattern inconsistency is even immense, there is 100% chance sensor position photometric intensity assignment proportion is very inconsistent from one bulb to other. Basically, photometric intensity measured at sensor is not representing overall output volume in same proportion, but hugely confusing calibration that way. Also, testing object to be inconsistent/unknown uneven surface level + specular reflective surface makes near field assessment very much subjective to ray enter angle.( as explained above, one of lamp shows consistent distribution pattern) Fog beam main target is road edge detection, much more diffused property. And then, spectrum sensitivity curve difference consideration is something needed to be added to assessment( of human eyes and whatever the camera sensor, and also BPX61) For fog lamp, valuable experiment to be driver view near field object recognition impression difference from commonly and correctly adopted F or F3 function fog optics, that has identically and natively assigned white or selective yellow emitter, not LED bulb ( they never replicate correct beam) at Average driver eye height 1.2m fog lamp mount height 0.6m aim maximum gradient 0.75D, gradient minimum 0.08 Within this projection mapping on the ground, how object recognition comfort changes depend on spectral balance of light source. This gradient aim equal to projection range as much as 46m. That's realistic fog evaluation shall be. There is reason why fog lamp has regulated gradient minimum and very specific photometric distribution requirement. Beam pattern ( gradient control), lamp mount height and illuminance intensity is far more important than anything else in fog situation. Vast majority of the time, "yellow" light source are typically dimmer than "white" light source being used in fog lamp, user simply seeing less intense light compare to white, feeling more comfort because it is not as intense as white. Another reason why yellow fog became a thing is, seeing different color than main beam gives some kind of phycological reward? or justification of " I did something" projecting white light onto road surface simply feedback at illumination level, but with yellow light, seeing some other element, color, that gives, oh yes I am seeing something. Not knowingly less illumination potency than white. They think seeing better because actually seeing actually less volume of light, but at the same time compensating lower illuminance with that colored impression phycological boost. as a result, feel more comfortable with yellow in fog. In that context, yes yellow likely could be perceived better in fog, just not in the reason of most of those made-up science explanation video you linked. Another resolution may be added to is type of optical system difference behavior. Reflectors may not be so much of difference, but not too few modern fog optics are now refractive beam control, result in pretty harsh chromatic aberration even at optics level, especially with LED light source. Lamp must be compact/low cost enough, light weighted, really not much space to correct, blends it other than smudge bit with very faint diffusion that won't compromise G-max value . So this already is creating slightly yet certain different gradient variance, isolated shorter wave length blue band is more frequently observed from refractive optics. Some of sample can show this as much as 0.25 degree above intended gradient ( which can be prevented by careful optical design, but many optics won't receive such consideration much, sometimes, aftermarket community even think that isolated blue color as exotic feature or something... ) that we can easily see such difference even at fog beam projection range. In this case, image gradient projection definition wise, less blue containing selective yellow light source is much easier to create better projection definition.
Getting a +150W RGBW movie lamp and doing these experiments in actual foggy conditions testing with a few far off signs would be a pretty cool thing. The movie lamps have an ability to attach shades, fresnel lenses, reflectors, etc and they also run on batteries / dc power. I wonder if there would be a distance component?
I don't feel comfortable judging the representation of the road hazards in dark/fog conditions on screen, because i have no way of knowing whether that would correspond to real-life experience. I did try yellow eye lenses for cycling at dusk and while they seemed to do something to improve adaptation and make the path more legible, it's difficult to say whether they really did.
I've found yellow eyeglass lenses to help with better distinguishing detail in bright conditions with snow covering, and with overcast, grey light.
White light seems better to me. Easier to distinguish different colour shapes.
My general experience over a few decades of riding motorbikes in some exceptionally crappy weather is that I find white light tending very slightly towards blue preferable, and warm biased light downright awful.
In terms of visual processing what I find here is that under warm/monotone light the only que you have to go on is shape perception - without any colour ques it is hard to discern real objects from billowing fog, and shadows. When broad spectrum light is used it is far easier to pick out shiney, man made, and coloured objects from the general noise in front of you.
Also, bonus point - I rather like xenon lamps over everything else for one curious side effect, despite some half baked efforts to filter out the UV, a large quantity of it is still emitted, this makes 'day glow' style paints light up unnaturally bright at night, and also whatever the British make their road signs, cats eyes, and road paint, and license plates out of chuck light back at you to a crazy extent. you might not be able to see anything else more than a few tens of feet in front you, but you'll see that stuff bouncing back at you thru it for hundreds of yards just fine. also another thing to keep in mind with xenon lamps is most of the light in the plasma discharge is emitted as a thin band in the middle of the beam, so it is possible to achieve a very narrow peak intensity angle, and when that is reflected back at you, the scattering potential is greatly reduced.
Thank you for that really detailed comment, especially about the UV content causing fluorescence in signage. I had not considered that aspect!
Is that Mark Felton's voice slowed down?
I'm honored that you think that my voice in any way compares his. He is a great story teller and his analysis of history is amazing.
Looks like the yellow halogen bulb did not emit a 'Selective Yellow' color based on the x, y coordinates. Didn't see what the measured yellow LED coordinates were. Selective Yellow is the color permitted for fog lamps besides white (UNECE R48 and SAE J578). Not sure this would have made much of a difference in the experiment though. The simulated fog moved too much around like a vapor which is not how fog behaves in a real world environment. Something else also to consider is that legitimate fog lamps designed in accordance to ECE/SAE standards would never illuminate road signage. I realize that the experiment needed visual targets inside the box but in the real world, signs should not be visibly lit by fog beams (unless the vehicle has lamps that call themselves fog lamps but aren't really fog lamps). These beams have a sharp cutoff and produce a wide, thin-like beam that produces short range illumination. They are meant to light the foreground and the sides of the roads to maintain lane keeping at slow speeds. They are not designed to reach far or act like low beams. Regarding the effectiveness of a selective yellow color compared to white, I believe more testing and research are needed to draw any meaningful conclusions.
Since the fog density is not homogenous because of its movement, would it be possible to make a sort of "temporal average" of a specific amount of pictures (don't know maybe 10, maybe 100 pictures)? I think It would be easier to make a comparison between the different colours/sources.
an actual difference is that warmer lights tend to make you sleepy, or so f.lux claims
I grew up with the belief that fog lamps were for the oncoming drivers benefit more so than the operator.
If you're ever in a foggy area where there are stoplights, simply look to see what color you can detect at what distance.
red is the shortest wavelength, you have to be rather close to it.
Yellow not so much and green goes way back there!
Red is the longest wavelength.
Not overly useful for fog lamps but you have fog and a multicolor LED. I've seen some studies that say green light will burn off fog better than other colors . It'd be interesting to pass a green laser through your red laser that's triggering the photo diode.. Not hitting the diode with the green laser but seeing if you can measure a difference in the fog with it and the response time it takes if any to see the difference if you happen to have an oscilloscope with a trigger. Another red & a blue laser would make for good tests to see which wavelengths are best.
As for the experiment though polarizing filters on the lights & the camera tested at different angles might be an interesting "spin" on it. Photographers use that to cut through fog and in a vehicle you could get some polarizing glasses and control both the light and the view and it might cancel most of the light that's scattered and unpolarized in the fog while what makes it to the sign and reflects back in phase appears amplified.
Growing up in Europe in the 70s and 80s, I often wonder why the switch from yellow to white lights on vehicles, I never thought this had anything to do with fog but unlike you, I never pushed the thought further! I would've tried green light since the human eye is also sensitive in that region, but then again, we bump against the same conundrum of sensitivity vs accuracy dilemma.. based on your test, I did not see a major difference between the colors. The car salesman made me laugh though!!! 😂 Another great video sir! How close are you from getting a camera and what model do you have in mind?
It is interesting that automotive manufacturers (who have the most to lose financially if there is ever a safety issue that results in recall), use white lamps as standard. In Germany, anything other than white is illegal. I always assumed that yellow lamps in France was just to help the French traffic cops to easily identify tourists, so they could hand out traffic fines...
I'm looking at used camera options to reduce the time it takes to get to a decent camera solution. Maybe a couple of months from being able to do that...
I'm looking at something from the Sony Alpha 7 series for now.
@project-326 lol!! These damn French 😆😂.... The A7 is a serious camera indeed! Nice!
You want to heat the bed of the test chamber and you need less turbulence in the fog, you also need to get a narrow but wide light beam as close to the bed.... Shining any light at eye level into a fog is going to impare your vision.... You want the ground lit up so that you can see it through the fog .....
Your video was nicely done... and the experiment was set up and documented really well...
HOWEVER... it's NOT just a matter of dynamic range...
It is widely accepted that THE HUMAN EYE has much better resolving power in the green range and rather poor resolution in the blue range...
This is why, on a typical DVD, which stores the image in RGB, the three colors are NOT allocated equal bandwidth...
The green image plane is stored at "full sharpness"...
(Because the green image is what contributes most to our ability to see details and perceive sharpness.)
While the blue image plane is stored at much lower resolution (HALF of the green resolution)...
(The blue image is really not sharp at all but we simply don't notice it because we are "less sensitive to blue sharpness"...)
(If you actually separate the colors in editing software you will see that the blue image is VERY fuzzy... but we simply don't notice.)
"Yellow glasses" improve visibility, and make what we see seem sharper, because they cut out the blue part of the spectrum...
By preventing the blue light from reaching our eyes, we see a slightly darker image, but with a higher percentage of yellow and green...
It is OUR EYES that work better in the yellow and green wavelength ranges and less well in the blue ones...
(As I understand it, the lenses in our eyes focus less sharply in the blue range, and we also have more sensors for the green/yellow range.)
Therefore the purpose of yellow fog lights is basically the same as using yellow driving glasses...
BUT THIS MEANS THAT YELLOW FOG LIGHTS WILL ONLY HELP SIGNIFICANTLY IF THEY ARE THE *ONLY* SOURCE OF LIGHT.
This means that they work well on a dark road in the woods at night with your "whites" off...
But don't work well at all if there is OTHER white light around (like streetlights).
And, in fact, if you drive into a lighted area, or oncoming headlights, after using yellows, the glare will be worse.
So you're probably better off using an effective pair of "blue blocker" driving glasses if it's foggy.
So, yes, in an otherwise dark area, you will have better "black and white visibility" with something like yellow sodium lamps than with white light...
But you will LOSE most color information.
As your video also pointed out... many modern signs use color as part of their signaling (like bright red stop signs)...
So things like Stop signs will be LESS visible under yellow light.
I thought the yellow fog lights worked like those yellow bug lights. Lol
🐝
Like perhaps you should try this again at scale because of the transflective properties of the signs .
In Germany fog lamps in yellow are forbidden.
French move over from yellow driving ligth to white.
More important is the high over ground if the fog ligth.
All other is culture. With your yellow ligth everbody in traffic know than we have fog..
I used to put fog lights on all my vehicles because I lived on the northern end of California's central valley and the fog could be so bad that I would have to follow the curb on my own street to get home (dodging parked cars).
I knew that fog lights have to be mounted as low as you can get them to get under the layer of fog and not just blind you with reflected light.
But then one day I thought "Why doesn't the CHP use fog lights if they actually work well?" and I stopped putting them on my vehicles.
thanks for the links, video and amusing auto play next video alarm countdown -alien self destruct style XD-!
Love the humor !!!!!
you can download a 3rd party application that can give you total manual controls over cellphone cameras, many are free like black magic
idea is that monochromatic or less wide range light helps you focus on features rather than content, so more vision power goes to analyze less information thus giving your brain better response times and thus better visibility, think how its easier to read a word on a clean white piece of paper rather than the word being written on a picture
I'll take a look at the black magic app, thanks for the info.
This video needs the Radiacode 103, not the 103G, and the unicorn Geiger taken to 10km, and then a discussion of the difference between readings…
Then bring on the multi color Christmas lights!
I use yellow glasses when driving at night. I think they really help with cutting down on the glare from the led headlights from oncoming traffic.
Despite the test result..... I think you still need to promote yellow light..
My argument.....
Yellow light are causing less temporary blindness to eyes in the opposite direction since we are not the only one who use the roads..
Just looking at street signs, the white is best. What about normal surroundings other than signage, like trees or the road surface. Low angle vs. High angle, etc.
What about UV light, or Laser Headlight ??
I think that might have some regulatory issues with potentially blinding people?
Muito bom, é assim que se deve analizar as coisas, com técnica, ciência e a verdade acima de tudo, procurando ajudar ao próximo!
Thank you, it is always our aim to do so...
I believe its just marketing bs. White light is sometimes even better
I think your color test is flawed.
I thought at first that the white light was better but now i think it's because of how glare works and how the light propagates from the position it's in.
I also think the signs you made should be more diffuse to prevent glare. you could treat the surface with 10 000 grit sand paper (yes that's ten thousand grit) to get the right effect for an object that small.
Given the tiny geometry of the test, the position of hte light makes a big difference, but it changes between the lights. What you should have done is added a jig where the lights slide into the same place and only once they're in place they turn on. this could be done by putting both lights in a fixture that holds them together and then putting the whole thing on rails, kind of like a train car on rails, sliding horizontally left and right. The light that's in place touches contacts that run the light. meanwhile you can edit out the frames where you're transitioning the lights so there's no confusing flashing.
Even though as you say in normal life fog will not be homogenous, there's two things to say: 1. Empirically, it will be homogenous to a large extent. I've never experienced fog irl that has such huge variation and visible vortices as your artificial fog, and I almost want to say it is always completely uniform. 2. Your fog moves around very fast, so when you're alternating lights, by the time you've switched the light the fog will have moved and the comparison isn't fair between both lights. To fix that maybe you could create a bunch of fog and use some sort of internal "mixing" fan to homogenize the fog. To help prevent the fog from falling out of the box, you could stand it upright so that the open wall is at the top.
Also another thought: are you controlling the intensity of the LEDs with PWM? I wonder if bright pulses of light in PWM are somehow registered by differently our eyes than a continuous light without PWM, assuming both would average to the same amount.
If you want to use an incandescent light and change its intensity without changing its temperature, use a normal filter over the reflector's front. It can be as easy as wrapping the filter in some gray translucent foil like used for christmas present wrapping or for adding tint to windows, but you might have to experiment a bit to find the right attenuation and to check the effect on the spectrum. You might want several layers of different attenuation and combine them kind of like a DAC's bits to build up the value you want.
Or indeed a variable neutral density filter for a camera. That's what I was screaming at him to try.
@@EE12CSVT don't variable filters give the light circular polarization? you might not want that for such a test.
Just LOL if you depend on squishy organs for data input. Incredibly narrow band "visible" light.
If you're not seeing radio through gamma, I don't know how to help you. Poor hairless apes.
Hope you get camera soon
I think it may have to do with levels of certain pollutants no shade intended just an observation.
Typically pollutants give a of more brown (ie reddish) hue, which due to Mie Scattering which is active in the 10 to 1000 nm particle size.
8:42 foam board
tks!
The mix of cells in one person's retina are different from everyone else's. This is going to be a subjective choice after your debunking of common assumptions.😊
omitting the halogen bulb was a mistake. the yellow and orange leds you used are all narrow band and are obviously going to perform poorly.
🙂
F$#go-meter brilliant.
Front fog lamps are just not useful regardless of color.
The rear fog lamps serves a purpose.
White light is clearly better (viewed by my eyes). It even makes the difference between seeing and not seeing some of the signs
The signs are not retroreflective, that’s a bummer
Today's modern LED and xenon based lights are far more effective when 'white'. That has been proven, including by your interesting experiment. Notice that 'white light' generally means a light source representing nearly the full visible light spectrum while yellow light reduced the spectrum that is used.
Although, it is still my impression that back in the day ('70 and '80) when incandescent lights had much less light intensity than what we have today and when the orange colored sodium street lights were still the norm, those yellow beams where much more effective to brighten up the obstacles of your path. I guess the 'yellow' aficionados are stuck in the past.
Filtering spectral ranges is like filtering information. Total dumb... maybe using thermal camera makes more sense.
Have you taken into account that a large percentage of the population wear corrective eyeglasses? Different wavelengths of light reach certain parts of the lenses at different times leading to distortion and glare.
Please look into the Duchrome test, also known as the Bichrome test, performed by optometrists. White light contains multiple wavelengths which converge at different points in the eye possibly leading to blurriness or depth perception issues, but with yellow light the eye has less to process.
I don't fully understand the process but have quite strong prescription eyeglasses (-5.5, -6) and astigmatism, and enjoy driving my older vehicles with older yellow 3000K halogen lights but hate driving my newer vehicle with white 6000K lights. I cannot see clearly with the white lights and driving at night is an unpleasant chore. However I don't suffer the same issues when switching back to the older vehicles with the yellow lights.
I also struggle with the new trend toward thin line turn signals, where the amber line appears to float around in relation to the car, depending on the angle of my head while looking through eye glasses. If the thin line happens to float in front of the headlight at night or near a reflection off the edge of the car from sunlight during the day, it will be invisible to be. It's a dangerous distraction that is extremely common amongst drivers I've mentioned the issue to, yet rarely discussed. This issue simply is not present on older cars with square or rectangular turn signal lenses.
Clear turn signal lenses make the issue far worse because instead of a large illuminated amber surface, people are expected to perceive 1cm square LEDs buried deep inside the housing (adding parallax error) while trying to figure out if the tiny dot of light is from the turn signal or a reflection from the sun or other nearby bright objects.
yeah people with astigmatic vision tend to like warmer lighting better, as do I, but I think this is more due to modern cool white LEDs tend to have ~120 degree light cast with very sharp luminosity dropoff at the edges, which aggravates the 'starburst' effect astigmatism causes. halogen & incancescent lighting in general cast their light in all directions, with a very soft luminosity dropoff instead, which likely leads to less eye strain.
'warm' LEDs also tend to have very thick phosphor coatings, at least compared to 'cool' ones, that mask the sharp casting pattern of the bare blue LED die by reradiating light past 120 degrees. I noticed high CRI LEDs of all color temperatures also tend to give me less eye strain, also likely due to very thick phosphor coatings, inferred from the lower effective luminosity per watt.
as someone who grew up in the mountains can tell you they absolutely work when correctly implemented
the problem comes with cars who have running lights
you can't use other lights with fog lights it makes them completely ineffective
🎉
Now i am going to comment just under 2 minutes in. Why the Ai voice? For me thats a goner
I live in mainland China and prefer some anonymity.
Yellow lamps are almost universally used to indicate a hazard, so whether there is any scientific reason for their use is rather moot. Yellow lights psychologically indicate danger like red lights mean stop and green lights means go. Blue lights are reserved for emergency vehicles, so go figure.
I have a pair of extremely expensive Zeiss glasses intended for flying an aircraft. These have a green tint to look at but are entirely neutral and don’t change the perceived colours when wearing them. What they do allow is better vision through fog, mist and haze, which is important when flying. The exact method used to filter scattered light is probably a trade secret, but they do work and allow you to see probably twice as far as with unaided vision. The lenses are not polarised because this would interfere with viewing LCDs in the cockpit, so some other method of filtering must be being used. I surmise a series of narrow band filter coatings sequentially applied to the lens to allow normal colour vision. Whatever process is used, it must be time consuming and expensive to justify the cost of the glasses.
In fog halogen works better than led or xenon. That is sure.
fell asleep
Chromatic aberration likely causes issues for some people driving while wearing corrective eyeglasses.
From Wikipedia: 'chromatic aberration, also called chromatic distortion, color aberration, color fringing, or purple fringing, is a failure of a lens to focus all colors to the same point.'
People suffering from certain common eye conditions might genuinely perceive while light consisting of multiple colours as more distorted than a single colour of light.
More than 50% of the population wears or will require eyeglasses at some point in their life, so this is something that should not be ignored.
Unlikely, very unlikely. Why would it be an impediment in fog in particular rather than for all driving or indeed all activities?
It's also the reason i don't really like polycarbonate and trivex corrective lenses. Some people get used to colour fringing and stop perceiving it; but CR-39 is what the cheapest lenses are made from and it's effectively free of the issue.
I've got cyl -6d on one eye which is a little spicy as in many manufacturers plain refuse to manufacture such a lens.
AI slop