alt Hacker NewsGuiding Ships with Moire Patterns
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This reminds me of pre-GPS systems like LORAN [0], where it also involves ship navigation by demarcating everything into patterned regions.
It's really neat that the author took the time to fabricate their own light.
I've been looking for something similar in concept for when I back into my garage from a side street with basically no driveway. It's a very narrow single-car garage. I can consistently back in well enough for myself, but if I'm not dead-on and I have passengers, passengers on one side of the car are going to have to squeeze to get out.
Essentially it can be hard to tell if I'm perfectly parallel with the garage walls and whether I'm off center, or rather if I'm within tolerance to back in even if the angle isn't perfect.
I've looked into building something like range lights [1], but I don't think the math scales down to short distances. Plus if I'm looking in the rearview mirror or my backup camera, neither of which are perfectly aligned with the direction of travel, that might mess with optical navigation aids.
I might have to dig into this moire approach to see if it would be more feasible.
Yes, obviously this is a minor inconvenience that I'm able to deal with on a regular basis, but it's fun to theorycraft.
Many runways have something called PAPI (precision approach path indicator) which does something similar. Basically you have four (or two sometimes for less precise version) lights which appear either red or white depending on whether you are high or low on the glidepath and you aim to get two reds and two whites - more whites means too high, more reds too low.
I can see that this would be not very intuitive for left/right guidance but are similar systems used in ship navigation?