[almatabata]

Back when they started, lidar cost a lot of money. They could not have equipped all cars with it.

The issue came when he promised every car would become a robotaxi. This means he either has to retrofit them all with lidar, or solve it with the current sensor set. It might be ego as well, but adding lidar will also expose them to class action suits.

The promise that contributed to the soaring valuation, now looks like a curse that stops him from changing anything. It feels a bit poetic.

[tzs]

> Back when they started, lidar cost a lot of money. They could not have equipped all cars with it.

But radar and ultrasound did not cost a lot and he got rid of those too, suggesting it was more than cost that made him go vision only.

Heck, they even use vision for rain sensing instead of the cheap and more effective sensor everyone else uses (which is just some infrared LEDs and photodiodes that measures the change in internal reflection at the outer side of the windshield when the critical angle changes when the windshield gets wet).

[almatabata]

> But radar and ultrasound did not cost a lot and he got rid of those too, suggesting it was more than cost that made him go vision only.

They did get rid of the radar at a moment when there was a shortage of parts. They had the choice, ship now without the part, or wait and ship less cars.

Maybe that was always the plan, and the shortage only accelerated the decision.

[palmotea]

> It might be ego as well

Might?

[spwa4]

I don't want to defend Tesla, but ... The problem with LIDAR is a human problem. The real issue that LIDAR has fundamentally different limitations than human sensors have, and this makes any decision based on them extremely unpredictable ... and humans react on predictions.

A LIDAR can get near-exact distances between objects with error margins of something like 0.2%, even 100m away. It takes an absolute expert human to accurately judge distance between themselves and an object even 5 meters away. You can see this in the youtube movies of the "Tesla beep". It used to be the case that if the Tesla autopilot judged a collision between 2 objects inevitable, it had a characteristic beep.

The result was that this beep would go off ... the humans in the car know it means a crash is imminent, but can't tell what's going on, where the crash is going to happen, then 2 seconds "nothing" happens, and then cars crash, usually 20-30 meters in front of the Tesla car. Usually the car then safely stops. Humans report that this is somewhere between creepy and a horror-like situation.

But worse yet is when the reverse happens. Distance judgement is the strength of LIDARs. But they have weaknesses that humans don't have. Angular resolution, especially in 3D. Unlike human eyes, a LIDAR sees nothing in between it's pixels, and because the 3d world is so big even 2 meters away the distance between pixels is already in the multiple cm range. Think of a lidar as a ball with laser beams, infinitely thin, coming out of it. The pixels give you the distance until that laser hits something. Because of how waves work, that means any object that is IN ONE PLANE smaller than 5 centimers is totally invisible to lidar at 2 meters distance. At 10 meters it's already up to over 25 cm. You know what object is smaller than 25 cm in one plane? A human standing up, or walking. Never mind a child. If you look at the sensor data you see them appear and disappear, exactly the way you'd expect sensor noise to act.

You can disguise this limitation by purposefully putting your lidar at an angle, but that angle can't be very big.

The net effect of this limitation is that a LIDAR doesn't miss a small dog at 20 meters distance, but fails to see a child (or anything of roughly a pole shape, like a traffic sign) at 3 to 5 meters distance. The same for things composed of beams without a big reflective surface somewhere ... like a bike. A bike at 5 meters is totally invisible for a LIDAR. Oh and perhaps even worse, a LIDAR just doesn't see cliffs. It doesn't see staircases going down, or that the surface you're on ends somewhere in front of you. It's strange. A LIDAR that can perfectly track every bird, even at a kilometer distance, cannot see a child at 5 meters. Or, when it's about walking robots, LIDAR robots have a very peculiar behavior: they walk into ... an open door, rather than through it 10% of the time. Makes perfect sense if you look at the LIDAR data they see, but very weird when you see it happen.

Worse yet is how humans respond to this. We all know this, but: how does a human react when they're in a queue and the person in front of them (or car in front of their car) stops ... and they cannot tell why it stops? We all know what follows is an immediate and very aggressive reaction. Well, you cannot predict what a lidar sees, so robots with lidars constantly get into that situation. Or, if it's a lidar robot attempting to go through a door, you predict it'll avoid running into anything. Then the robot hits the wood ... and you hit the robot ... and the person behind you hits you.

Humans and lidars don't work well together.

[rdsubhas]

Wasn't the angular resolution solved by having spinning lidars?

[Mawr]

> It takes an absolute expert human to accurately judge distance between themselves and an object even 5 meters away.

Huh? The most basic skill of any driver is the ability to see if you're at a collision course with any other vehicle. I can accurately judge this at distances of at least 50 meters, and I'm likely vastly underestimating the distance. It is very apparent when this is the case. I can't tell if the distance between us is 45 vs 51 meters, but that is information with 0 relevance to anything.

> The result was that this beep would go off ... the humans in the car know it means a crash is imminent, but can't tell what's going on, where the crash is going to happen, then 2 seconds "nothing" happens, and then cars crash, usually 20-30 meters in front of the Tesla car. Usually the car then safely stops. Humans report that this is somewhere between creepy and a horror-like situation.

This is a non-issue and certainly not horror-like. All one's got to do is train themselves to slow down / brake when they hear the beep. And you're trying to paint this extremely useful safety feature as something bad?

> Worse yet is how humans respond to this. We all know this, but: how does a human react when they're in a queue and the person in front of them (or car in front of their car) stops ... and they cannot tell why it stops? We all know what follows is an immediate and very aggressive reaction.

What are you trying to say here? If the car in front of me brakes I brake too. I do not need to know the reason it braked, I simply brake too, because I have to. It works out fine every time because I have to drive in such a way to be able to stop in time in case the car in front of me applies 100% braking at any time. Basic driving.

Generally, what you're describing as predicting is more accurately called assuming. Assuming that things will go how one wants them to go. I call that sort of driving optimistic: optimistically assuming that the car in front of me will continue going forward and that there is nothing behind that huge truck that's blocking my view of the upcoming intersection, so I can freely gas it through.

That mindset is of course wrong; we must drive pessimistically, assuming that any car may apply max braking at any time and that if any part of our line of sight is obstructed, the worst case scenario is happening behind it - there is a high speed object coming towards us at a collision course that will reveal itself from behind the obstruction at the last second. Therefore, we must slow down when coming around a line of sight obstruction.

[tzs]

> Huh? The most basic skill of any driver is the ability to see if you're at a collision course with any other vehicle. I can accurately judge this at distances of at least 50 meters, and I'm likely vastly underestimating the distance. It is very apparent when this is the case. I can't tell if the distance between us is 45 vs 51 meters, but that is information with 0 relevance to anything.

That's probably because for things moving in straight lines at constant velocity you don't need to be able to measure distance at all accurately to figure out if they are on a collision course. You just need to be able to tell if the distance is decreasing.

First, you just have to note if their angular position is changing. If it is then they are not on a collision course.

If the angular position is not changing, then you have to check if the distance is decreasing. If it is they are on a collision course. If it is not then they aren't.

If you take advantage of the fact that cars generally have distinctly different front ends and back ends and that most of the time cars are traveling forward you don't even have to estimate distance. If the angular position is not changing just note if the direction the car is pointing has its front closer to you than its back or not. If its front is closer than its back then it is on a collision course. Otherwise not.

You will need to make some adjustments due to cars having volume. A near miss for point cars could still be a collision for cars with volume, but this should be fairly easy to deal with.

[spwa4]

> Huh? The most basic skill of any driver is the ability to see if you're at a collision course with any other vehicle. I can accurately judge this at distances of at least 50 meters

Can you tell me the distance between 2 objects, each 50 meters away from you, down to 1 cm? That's the superhuman part. Even the distance between you and an object 10 meters away down to a few millimeters is impossible for a human.

[queenkjuul]

And that's not remotely relevant to driving a car

[spwa4]

It is because 10 measurements of that per second can predict with great accuracy where every object in the scene will go for the next few seconds, except for small children or bikes or ... that the LIDAR cannot see.

It can also tell you 4-5 seconds before it happens which objects are going to collide. Not just which object YOU are going to collide with, but any collision between any 2 objects if they are within the range of the LIDAR.

But they see fundamentally different things than humans. So humans will never work together nicely with LIDAR guided robots.