Cameras only see one colour per pixel (i.e. Bayer colour filter array). Because our eyes are not so acute at resolving colour compared to luminescence this tradeoff works well.
But in this context I'm not sure at a pixel level how much 'extra' information is added by _removing_ red/green from the blue pixels, green/blue from the red etc.
In other words, if the image came from a digital camera, to actually stuff more information into the same number of pixels, colour may or may not help. In any case working with the raw CFA bayer source image would almost certainly be beneficial over interpreting the image after it has been converted to a normal RGB image (losing information in the process)
This is an interesting point, but it assumes perfect optics. If the image is slightly out of focus, I think three lower resolution images in different spectral regions is a big win.
I think it depends on the context - if you're designing the whole system from bar code to camera, I'm not sure that the color will help. But in that case you can assume close to perfect optics and I'm not sure if you would find an improvement or the opposite over a monochrome setup with better SNR.
On the other hand if you're stuck with things like mobile phone cameras, and can only control the bar code side, then Id imagine you'd see some improvements as you say.
An interesting middle ground would be if you could get the raw image from the sensor before a generic debayer algorithm gets applied.
Good luck, keep up the good work... i've worked commercially on optical barcode systems and it's a super interesting topic (tho looks like my post has been downvoted out of existence so maybe you wont see this).
I don't want to represent myself as one of the inventors! I just saw this on HN, skimmed the technical report, and found a bunch of comments on HN that could be answered with my cursory knowledge thus gained.
What I can offer is that it is now possible to get memory buffers containing "raw" sensor data from mobile phones. I've only done it on iPhone so far, but the "camera2" API on Android looks to support this as well. It only works in single-shot photo mode - I suspect there isn't the bandwidth to do 30 fps streaming, and they rely on the ISP for debayering and color space conversion in video mode.
iPhones seem to have negligible chromatic aberration in their raw output, weirdly, so that isn't a blocker for full sensor resolution grayscale imaging. Someone could exploit this to write the world's greatest mobile phone QR reader app.
There is a real, if small, chance that there could be a general election in the UK soon and potentially a more favourable labour government. If I were Assange I would do whatever I could to hang in there at least long enough to rule that possibility out.
Yup it did - I was flying aerial surveying at the time. Bad timing. Actually I didn't notice anything in the end so was all good but when I saw the NOTAM I couldn't believe my bad luck.
Not sure whether you're agreeing or disagreeing, but that refers to jamming done by electronic warfare units, not part of the GPS system, as I indicated above.
I really want this to be a thing, but my rough calculations given the total cross section area of the sail and the average wind conditions on shipping routes come out to as close to nil as makes any difference for ships these size.
I posted a very rough calculation on the last HN post about this and got downvoted for some reason. I guess everyone else wants this to be a thing so much they are happy to set aside physics through sheer force of will. HN people and the investors / instigators of this project.
This is one time I'm desperately wanting to find out I'm completely wrong.
My last post in a nutshell - these things are order of magnitude the same size as the sail on my own sail boat. Forget about the type of sail. Even if 100% of that wind energy was converted to forward motion it's going to do essentially nothing in the context of a big ship.
You were downvoted because your calculations were for regular sails, and sailboats, instead of for Magnus effect.
Wikipedia says:
F = L*rho*v*2*pi*r^2*omega
where L is the length of the cylinder, rho is the fluid density, v is the fluid velocity, r is the cylinder radius, and omega is the cylinder angular velocity.
What angular velocity are you assuming in your calculations?
My back of the napkin assumed all energy from the wind over the entire cross sectional area.
Magnus effect or not, i'm just dealing in orders of magnitude and for the average wind speeds on shipping routes, I just don't understand how this works even if 100% of the wind energy is extracted from the cross sectional area of the sail.
After looking at the math a bit (including the one helpfully provided above), I think you're missing alot by ignoring the effect of the rotational velocity when thinking about this effect. The spinning rotation has a multiplier effect on the air movement similar to a how a much larger/fuller sail could redirect the air flow to produce more forward motion in a traditional sail.
[Edited] The effect is similar to how a rotational wing aircraft also produces lift that is not strictly proportional to the area of the wing (although for different reasons).
Without seeing your back-of-napkin numbers it’s hard to know where you might be going with this, but the idea that sail efficiency has something to do with the amount of energy in the wind in a particular cross section seems in need of justification. You’re probably better off considering air/sail interactions as a momentum transfer - the goal of the sail is not to extract all of the energy from a packet of air (presumably leaving blocks of frozen nitrogen in the sail’s wake), but rather to extract as much forward momentum as possible out of the interaction, leaving the air with more rearward momentum than it started with.
No, I don’t think that’s what it’s doing. It’s actually powered - using electricity to make it spin. As a result of the spin, it creates vortexes that push 90 degrees to the wind.
I understand that, in fact probably uniquely to people on this thread I've been on a rotor sail boat (not sailing though, in dock).
They do work when the ratio of the sail area to the boat is appropriate. In the case of the one I went on it was a very efficient hull too - very light weight catamaran.
The ships in the article you link have huge sails on reasonably small ships. The ones suggested by Norsepower are absolutely tiny compared to the ship. They are, like i've said, about the same cross sectional area of a small pleasure sailing yacht on huge container ships.
No I don't, my calculations at this stage are as follows:
Sail area - same as my 10 ton boat. Gets me to 7kts in a good strong wind.
Boat they intend to install it on: 110000 tons!
My point is that for this to have any impact at all, a massive amount of energy has to be extracted from the wind. An amount of energy that just doesn't exist in the volume of moving air they are talking about.
This is more complicated - you ignore hull speed for one. Amount of force needed to move ship through waves is non linear: https://en.wikipedia.org/wiki/Hull_speed
I build camera gear for 172s and fly (as passenger, not pilot) probably 20-30 days per year, sometimes much more, and I get nervous at <60kts at low altitude.
40kts IAS is I guess around the full flaps stall speed but you sure don't want to be doing that intentionally. At least not with me in the plane please.
My small 12 meter long boat has a sail area of 900sqft. When sailing perpendicular to the wind it captures pretty much all of that.
The sail on that ship is 100' high, and looking at the aspect is around 15' wide, or 1500sqft. That type of sail I think only harneses half of that area, so half of 1500' or 750' best case.
I can say with complete confidence that if all the energy from two of my boats were towing one of those ships, even in a hurricane, it's going to increase fuel efficiency by approximately 0.0%
EDIT: I just did a random sample of wind speed [1] of points on the globe on international shipping routes [2] and it looks like they are generally around 10-15km/h. Thats barely enough to get my boat up to speed. There is a reason sailboats take very particular routes and don't just go from point A to B
People have been complaining about HN turning into Reddit for at least 10 years. In fact, the HN guidelines used to ask people not to complain about HN turning into Reddit ("it's a semi-noob illusion"). But when we augmented the guidelines a year or so ago, we took out that one to preserve brevity.
The mods discourage humor because it tends to metastasize into tedious offtopic threads, which I guess is true enough.
Readers think they punish bad jokes and reward good ones, but the stupid Butts pun is doing great while the absurdist gem about Leonard Nimoy secretly wanting to be Kirk and living it out for a year in the white pages (and then someone working with him forgetting his name!) was nuked from orbit.
I really like the UI design that goes into avionics - the fact that every possible scenario has to be thought out and handled, and that the end result has no flashy eyecandy or extraneous functionality; it's all function, it's all required (or it's not there); everything on the screen at any given time is significant, and (hopefully) care is taken that the amount of data (ie, significance) showing at any one moment is not information overload. A very hard balance to get right, I'm sure.
The rigor and discipline imposed over the process of software architecture and implementation in aviation (moreso than medical devices, it would seem) is both inspiring and instructive, and I definitely look up to it.
I must admit I'm genuinely interested to learn more about how the role of UI design plays into avionics construction - I've leaned toward UX for quite a while (I think I started headscratching about the subject around 13-14, although I didn't know that was what it was called at the time) and I think it's probably something I'd do pretty well at when I'm finally looking for a job. Web UX is... frustrating and demotivating, though. I don't want to kill myself doing that.
But in this context I'm not sure at a pixel level how much 'extra' information is added by _removing_ red/green from the blue pixels, green/blue from the red etc.
In other words, if the image came from a digital camera, to actually stuff more information into the same number of pixels, colour may or may not help. In any case working with the raw CFA bayer source image would almost certainly be beneficial over interpreting the image after it has been converted to a normal RGB image (losing information in the process)