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They very well may be doing the latter as well, but Tesla has specifically said that their camera reads the speed from road signs[1] [1] http://www.teslamotors

They very well may be doing the latter as well, but Tesla has specifically said that their camera reads the speed from road signs[1] [1] http://www.teslamotors.com/blog/dual-motor-model-s-and-autopilot http://www.teslamotors.com/blog/dual-motor-model-s-and-autop...

joosters 11y ago
Reading road signs is exceedingly tricky. It's not just the OCR, there's plenty of other gotchas. e.g. what if you miss a road sign because you were overtaking a truck when the sign went past? Road signs also have situational contexts. e.g. in the UK there are road signs indicating a max speed for an upcoming sharp bend (or series of bends) in the road. There isn't always a matching speed limit sign after the bend because drivers are assumed to work that out for themselves. But will the cars do so? Or will your self-driving car get stuck at the lower speed?
- sandworm101 11y ago
  In my jurisdiction the yellow "limit" signs before corners are not actually speed limits, just references. You are allowed to disobey them at your peril. Sometimes that means you can do 80kph around a "30" corner, a common situation on mountain roads. That also avoids the enforcement problems such as where the new limit should being and end, and the difficulty of measuring vehicle speed through a corner.
- njharman 11y ago
  > Reading road signs is exceedingly tricky. You (and parents) vastly overestimate difficulty. They are reflective, high contrast, using known font and very limited symbols (0-9). Car CV systems can distinguish pedestrians from background, they can read a freaking sign.
  - wibr 11y ago
    You have to distinguish the sign from signs on trucks (indicating their maximum speed), reflections of signs in windows, you have to recognize the sub-signs which might limit the scope of the main sign (speed limit might only apply to exit or under certain weather conditions), then there are the usual adverse conditions like rain, reflections, dirt, plants, shadows etc.. Just search for "german traffic sign recognition benchmark" to see what the state of the art is (ConvNet).
    - njharman 11y ago
      It knows where cars and the lanes are. So no it doesn't think there are speed signs in middle of road or on a truck. Sub signs I'll give you. Don't have any where I live though. Compared to all the other things it must do reading signs is on the easy list.
- ascorbic 11y ago
  Speed limits almost always have repeater signs at regular intervals, particularly when it's not national speed limit. The recommended max speed signs on bends are different from speed limit signs too. If there's not a red circle, it's not mandatory. The exception is national speed limit signs, which would require the car to see if it's a dual carriageway or not so it can switch between 60 and 70.
pbhjpbhj 11y ago
So can you cause a pile up by putting up a fake road sign with a speed limit of 0 or 1mph and waiting for a Tesla to come along??

joosters 11y ago

Reading road signs is exceedingly tricky. It's not just the OCR, there's plenty of other gotchas. e.g. what if you miss a road sign because you were overtaking a truck when the sign went past? Road signs also have situational contexts. e.g. in the UK there are road signs indicating a max speed for an upcoming sharp bend (or series of bends) in the road. There isn't always a matching speed limit sign after the bend because drivers are assumed to work that out for themselves. But will the cars do so? Or will your self-driving car get stuck at the lower speed?

sandworm101 11y ago
In my jurisdiction the yellow "limit" signs before corners are not actually speed limits, just references. You are allowed to disobey them at your peril. Sometimes that means you can do 80kph around a "30" corner, a common situation on mountain roads. That also avoids the enforcement problems such as where the new limit should being and end, and the difficulty of measuring vehicle speed through a corner.
njharman 11y ago
> Reading road signs is exceedingly tricky. You (and parents) vastly overestimate difficulty. They are reflective, high contrast, using known font and very limited symbols (0-9). Car CV systems can distinguish pedestrians from background, they can read a freaking sign.
- wibr 11y ago
  You have to distinguish the sign from signs on trucks (indicating their maximum speed), reflections of signs in windows, you have to recognize the sub-signs which might limit the scope of the main sign (speed limit might only apply to exit or under certain weather conditions), then there are the usual adverse conditions like rain, reflections, dirt, plants, shadows etc.. Just search for "german traffic sign recognition benchmark" to see what the state of the art is (ConvNet).
  - njharman 11y ago
    It knows where cars and the lanes are. So no it doesn't think there are speed signs in middle of road or on a truck. Sub signs I'll give you. Don't have any where I live though. Compared to all the other things it must do reading signs is on the easy list.
ascorbic 11y ago
Speed limits almost always have repeater signs at regular intervals, particularly when it's not national speed limit. The recommended max speed signs on bends are different from speed limit signs too. If there's not a red circle, it's not mandatory. The exception is national speed limit signs, which would require the car to see if it's a dual carriageway or not so it can switch between 60 and 70.

pbhjpbhj 11y ago

So can you cause a pile up by putting up a fake road sign with a speed limit of 0 or 1mph and waiting for a Tesla to come along??