Somebody correct me if I'm wrong, but Google cars still can't drive in the rain or in the snow. Not even on a wet street. They have driven all those thousand miles in Mountain View, Calif. in good weather.
Generally lidar's don't work well with rain or reflective surfaces.
Indeed — I remember a projet in high-school, explaining how lidar were being used to measuring rain drops direction…
The thing is: there apparently now is a technology (at Mercedes or BMW) that uses beamers instead of front lights; a secondary camera detects droplets’ movement, predicts their fall and the beamer doesn’t shine light precisely on them. It helps light in front of you at night without shining mainly the rain. I was stunned when I learned we are now that fast. Same thing with cooking mosquitoes with lasers. I’m assuming that with those tech handy, a lidar should work properly through the rain. It leaves braking as a problem, especially on black ice — and that one is tougher.
BMW does have an interesting new headlight system available on the coming i8 which boosts the high beam range using lasers, which is still pretty cool but doesn't avoid rain.
My understanding is that it uses vision processing algorithms on a camera nowadays, and works just fine in rain. Snow is an issue because the car can't see the lane markings through the snow -- a human drives through snow by remembering where they were or making a guess.
A computer can do dead-reckoning off of fixed objects (buildings, bridges) and remember a millimeter-level resolution map of where lanes are better than any human.
They still have trouble in snow. I think that's fine for a first version.
I fully expect the first consumer versions of automatic cars will have a "No, I won't drive for you today, Dave" mode. Driving in everything but snow would still be a huge win.
And if you ever look at a large parking lot after a thaw when it had been snowing earlier in the day you can see we're also horrible at predicting where the lines are and, for the most part, use other drivers as our guide.
There's a relatively simple fix for lane markings, that would help autonomous cars even in good weather. You know those reflective lane marking doodads they embed in the road surface? We start replacing them with magnetized nails that are pounded into the asphalt in intervals. Sensors in the car could recognize the lanes even in deep snow or pea-soup fog. And homeowners could easily outfit their driveways with a trip to Home Depot.
They don't use the embedded ones in most parts of snow countries like Canada, because it's hard to get them flush with the road so that they work with snowplows. AFAICT, Toronto still uses just plain old paint on most of its roads.
I am also curious about multiple vehicles using LDAR at the same time. Is it possible for two or more vehicles to operate using LIDAR independently, or must they synchronize with one another and how far apart do they have to be?
Generally lidar's don't work well with rain or reflective surfaces.