Why are there no commercially available helmets with HUD's?

Ahem...may I recommend Fortnine's video on smart helmet to shed light on why they aren't a thing.

https://youtu.be/IiACV0Ly4j4?si=Zrg1_5Uhdevy-Lna

Have fun

Tl:dr he has no real point.

He just lists two failed smart helmet startups, then talks about a successful smart helmet that doesn't use a full HUD but uses an LED light bar. The only actual point he makes is that it's hard to make a display that's visible in the sun.

It's also a motor cycle channel so he makes points like "why not use your mirrors or built in dash" which is not really applicable to cyclists, eskaters, EUC users, etc.
- Fair reasoning but I still think Ryan is in the right path.
  
  He is right that shoving a holographic display and the computer bits in the helmet either makes it bulky, heavy, and useless or you'd be paying up the wazoo for what is an engineering exercise.
  
  A simpler interface that solves current problems in my opinion would be much better than trying to make an Ironman helmet.
Here is an alternative Piped link(s):

https://piped.video/IiACV0Ly4j4?si=Zrg1_5Uhdevy-Lna

Piped is a privacy-respecting open-source alternative frontend to YouTube.

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It’s very dangerous to focus your vision four inches in front of your face while driving. It also takes a second to switch from distance vision to being focused so close, which undermines the whole “at a glance” value of a HUD. Race cars have instrument panels pushed as far away from the driver’s face as possible to make the focal length changes inside your eye easier and faster to switch between. A helmet HUD is the extreme opposite of that.

That is not an issue with anything that is supposed to act as a HUD, as they project the image in such a way that it looks to be further away. They have to, because humans are terrible at looking at something that close to their eyes anyway.
Google Glass for example projected it so that the image looked like it was 2.5 meters away from your face.
- I'm really curious what the Google Glass concept would be like with modern technology. I feel like the form factor was poisoned from the backlash at the time, but it seems so much more viable than the stupid bulky headsets.
Lensing. BMW HUDs bounce off a few curved mirrors before reflecting off the windshield so some key details appear 30ft in front of the car. Meanwhile, VR goggles have the screen unfocusably close but due to lenses inside, objects can appear any distance away (and it's not just parallax, there's near and far focus)
My Cadillac has a video display as a rear view mirror and it has that issue. With a traditional rear view mirror your focal length doesn't change much, but in my car your focus has to shift to the mirror 2 feet away.

It has upsides though, as passengers or objects in the rear seat don't affect your mirror view.

Whenever I change vehicles it takes a few minutes to readjust.
What if the helmet had a camera that projected it's view along with the hud? You might lose some depth perception but at least you could see the road while looking at the HUD.
- Now you’re talking about mix reality VR. Like driving with an Apple Vision Pro on. The technology isn’t good enough for this yet. Maybe someday.

To me a hud would be useful for two things, in this order of importance:

A rear view mirror right at the top middle of my field of vision, so I could check what is behind without losing track of my front;
A GPS.

Gimme those and I will be throwing money at you faster than my wallet can hold it.

Development costs, lack a research into it, and a lack of companies willing to take on that financial risk for a (mostly) untested market

Not to mention the costs of such a device with any kind of feature set other than just a glorified screen

Undeniably there's been some tech developments that could lead in such a direction but there's still some substantial hurdles to clear first

Like a motorcycle helmet? I'd love one, show my speed, maybe a gps overlay, rearview, etc. That'd be great.

Control music with my tongue
- Everything reminds me of her

I'd rather see a HUD on a car windscreen before I'd want a helmet HUD

Um. Those have existed for years.

Contrast. You can't use light to make something dark.
In the HUDs that we do have (Hololens, Google Glass), you typically use something like DLP or waveguides. Both are pretty expensive.

There are fewer barriers with helmets because they are usually tinted.

I'm a fan of anything that keeps eyes more forwards/on the road.

Motorcycle helmets? Sounds like a great way to become an organ donor.

Doing it right can actually prevent organ donations. Like having speed shown without the need to take eyes away from road.
- I dunno, if you're relying on a number to determine if you are proceeding at a safe speed, I am a bit skeptical you have sufficient mastery of whatever motor vehicle you are operating.
  
  Just as if you're relying on a speed limit sign & law enforcement to control what speed drivers go rather than road design feedback, you have insufficient mastery of your engineering trade.
  
  https://www.strongtowns.org/journal/2023/6/22/facing-an-uncomfortable-truth-about-speed-limits
- Ok. Limited HUD I agree would be useful.
- a HUD would be more in your field of vision in terms of the X and Y dimensions, but in the Z dimension, depth, in the worst place of all.
  
  Focusing your eyes an inch away from your face is, unfortunately, taking your eyes off the road. The closer something is to you, the greater and greater focal length change is required. Switching between road vision and 1-inch off your face is much much harder than switching between road vision and 24-inches away from your face (where conventional speed dials are, on the handlebars).
  
  It’s not just about the time and effort it takes to do this. When your eyes are focused 1inch away, everything on the road will be super blurry. When your eyes are focused 24 inches away, the road will not be as blurry, and it’s easier for your eyes to jump back onto the road.

I wouldn't be surprised if there was some sort of safety rule about looking at a screen.