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Comment by isoprophlex | Hacker News Reader

"LIDAR is a fool's errand. Everyone relying on LIDAR is doomed." edit: beat me to it

it snowed a few weekends ago in Chicago, my autopilot turned off because snow covered up the cameras. So I am not buying all this "self driving with no lidar" brouhaha

Can snow cover lidars?

Depends on the unit. On some designs (e.g. Velodyne HDL-64) the unit is split into two sections. The whole upper section, along with all the optics and some of the electronics, spins at 10-15 Hz, which naturally tends to shed precipitation and other crud.

Sensors with non-moving optical windows can use other strategies, such as air knives or wipers.

Doesn't LIDAR has similar problems with precipitation? Regardless of what solution proves to be the best, there is going to be a decent amount of time between when a self driving car can handle most scenarios and when it can handle all possible scenarios.

Here's a snow cover map of North America on a random day in January:

https://www.natice.noaa.gov/pub/ims/ims_v3/ims_gif/ARCHIVE/U...

Here is Europe and Asia on the same day:

https://www.natice.noaa.gov/pub/ims/ims_v3/ims_gif/ARCHIVE/E...

For someone who lives in or close to that white part, "most scenarios" includes snow. Arguably for Level 4 autonomous cars in those areas, you either need to fully disable autonomy in September and enable it again in late April, or you'll need to handle snow.

You are comparing two different things. Old snow on the ground (your images) is not the same thing as active or recent snow accumulation on the vehicle (the original comment). It is completely reasonable for the car to disable autonomy due to snow accumulation until someone clears it off the vehicle. That says nothing about the autonomy of the vehicle with snow cover on the ground.

I'm assuming Level 4 is what Musk means by Full Self Driving. The bar to be passed is then

"No driver attention is ever required for safety (...) self-driving is only supported in limited circumstances (e.g. geofencing), and when these circumstances are no longer met the vehicle must be able to safely abort the trip, e.g. park the car, if the driver does not retake control."

How would that work if you're out driving on the highway, and it starts snowing hard so the car can't see anything? Just park on the highway?

If your car can't safely handle such a scenario, the automous feature would have to be "season-fenced" in addition to geofenced.

It isn’t like it all cameras simultaneously go from 0% obstruction to 100% obstruction instantaneously. The car should pull off the highway and park or at least pull to the shoulder and park once it has identified decreased visibility to an extent that might impact safety.

It kinda is though. Snow deposition is a function of surface temperature, which is uniform across the sensor. Hit the wrong initial temp when you enter a blizzard, and deposition takes your vision in seconds. It can be hard enough to see out the windshield which has heating, wipers and anti-freeze wiper fluid fighting for it.

Do you realize how far you have moved the goalposts during this conversation? You started out with the suggestion that they "fully disable autonomy in September and enable it again in late April" and now you are talking about situations with "the wrong initial temp when you enter a blizzard".

I will simply refer back to my initial comment in this thread: "there is going to be a decent amount of time between when a self driving car can handle most scenarios and when it can handle all possible scenarios". Blizzards are not in the "most scenarios" group. Barring emergencies, no one should be driving in a blizzard let alone an autonomous car.

I don't think OP has moved the goalposts at all. LIDAR can work in snow but cameras get covered. And yes you are right, there will be a decent time between testing in some basic scenarios and testing in all scenarios. But I do not understand why Mr. Musk is trying to reinvent the wheel and rely only on vision when LIDAR has already shown that it works better.

https://www.cambridge.org/core/journals/journal-of-glaciolog...

> But I do not understand why Mr. Musk is trying to reinvent the wheel and rely only on vision when LIDAR has already shown that it works better.

Because he's sold a bunch of cars (and a bunch of stock in the company selling the cars) without LIDAR with the explicit claim they are hardware-ready for full self-driving.

Snowstorms can last for days.

Freeway shoulders are not safe places to stop. You're likely to get hit by a drunk or distracted driver. Ask any police officer or tow truck driver. That's why stopping on the shoulder is only for emergencies.

Water affects certain wavelengths, and there's been good progress on LIDAR that uses wavelengths that aren't effected.

Most approaches want to use a wavelength that has as little ambient light as possible. That light is absent precisely because it is absorbed by water vapor in the atmosphere. The alternative approach must deal with lower signal:noise, but is not substantially affected by weather.

OK but snow blocks lidar too.

snow might ruin it for everyone. Winter is coming, and we're all screwed...

Not cleaning snow off of your vehicle before driving is crazy.

And would you drive if snow covered your windscreen? Or would you clean it? Which is obviously possible for cameras too.

The windscreen has wipers, on the Tesla model 3, I don't think all the sensors have wipers... so that's an issue.

Yes, we implemented simple physical solutions such as wipers and window heaters in cars to maintain vision for drivers. What we didn't do was implement lidar to aid human drivers.

Simple physical solutions are available if necessary for the cameras too. I don't have a tesla so I don't know what measures they use to keep the cameras clean but I'm sure they've thought about it and designed for it.

Great-grandparent comment suggests that they did not, in fact, design for it. Assuming the best is nice when you have no information, but we have information.

I'm not assuming the best, I'm assuming basics. We've just watched a presentation where Tesla put immense resources and talent into designing a state of the art vision processing chip. Do you think they're going to let it be rendered useless by not implementing simple physical measures to keep vision coming in from the cameras? (What measures are already there plus easy opportunity for improvement). Of course not. Such a line of argumentation is transparently bogus. I don't know why the top level commenter's autopilot turned off in the snow but trying to argue that that shows that snow renders cameras useless and makes lidar necessary is stupid. Sorry for the strong language but really, I don't know how else to put it.

The basics. Like having a trunk lid design that sheds water properly?

https://teslamotorsclub.com/tmc/threads/water-dripping-into-...

Shut down the company the trunk is slightly off.

Tesla is new to the game, give them a few more cars to catch small stuff like that.

Tesla has been around for 16 years, so I think it's not too critical to expect them to be able to sweat the small stuff.

16 years is a tiny fraction compared to the other car companies you're comparing it to.

But ask yourself, what's more likely, the other car companies catch up to their AI and battery tech, or Tesla fixes the trunk in the next model?

I have seen recent Teslas in person in the showrooms, and there doesn't appear to be any wiper for the cameras. Especially with a firsthand owner account just a few comments up I think it's actually only logical at this point to assume they didn't put wipers on the cameras.

I would think that heating the glass (and surrounding casing) would be a more effective measure for keeping a camera clear of snow.

Well they didn't do that either. They didn't do anything for it. But don't worry, FSD is just around the corner and the cars have all the hardware necessary, it's just a software problem now. And this time it's different than in 2016 when they said they had all the hardware they needed. And it's different from 2015 when they said the FSD was coming in 2016.

It's not that hard.

In our 2005 DARPA Grand Challenge vehicle, we had a system to clean the camera and LIDAR. It used a spray nozzle, and alternated spraying windshield cleaner and air. This is a commercial truck accessory used on mining trucks.

Snow completely disables lidar as well if I recall correctly. Only radar will work in a snowstorm.

Lidar is useless when snowing

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