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Naïve answer : We humans drive cars despite only visual and audio information? We interpret and often miss things or get fooled by optical illusions. I remember

Naïve answer : We humans drive cars despite only visual and audio information? We interpret and often miss things or get fooled by optical illusions. I remember a great story a year or two back about one of Google's cars "weirdly" stopping, before the reporter realised it'd somehow seen through a hedge and noticed a cyclist about to pop into view? I imagine lidar gets you one step closer to the data you're really after.

hyperbovine 10y ago
How does lidar see through a hedge?
- xnzakg 10y ago
  Probably was a radar, not a lidar.
- mseebach 10y ago
  Possibly infrared sensing? Some fancy IR cameras can see a human body through walls, so I guess it's not inconceivable that a LIDAR (which is already IR, I think?) could penetrate a hedge.
  - swiley 10y ago
    You're thinking of far IR (typical black body radiation at room temperature for most materials) near IR is what has to be filtered out in web cams and what a lot of these LIDAR devices use, it behaves almost exactly like visible light.
- willvarfar 10y ago
  LIDAR can practically see through vegetation. Some individual beams miss the vegetation and reflect from things they hit on the far side, and the software can detect this. This is used a lot in mapping and research into e.g. forest canopies in the amazon. LIDAR has been extensively deployed on aircraft for this kind of purpose. I've seen high-res LIDAR scans made available by my country's state survey for e.g. archeologists and it has the 'true ground' through the vegetation. Its like the vegetation has been stripped away and has a clinical feel when rendered.
  - mturmon 10y ago
    This is a good summary. Some lidars also offer two distance estimates per point, a first distance and a secondary distance. On the lidar I used that had this capability, the secondary distance was not always robust. But on permeable materials like vegetation, the secondary distance would typically indicate solid materials behind the initial curtain of material. Anyway, the presence of multiple distance returns in a small solid-angle area (whether from the above primary/secondary, or from nearby scan points) can indicate density of vegetation. You can certainly see "through" the small gaps in a hedge. Depending on the lidar, and the range, gaps as small as a few cm^2 could be enough (talking about vehicle-mounded lidar for autonomous navigation, not remote sensing of forest canopy).
Cybiote 10y ago
Humans have a bit more information than that -- tactile, proprioceptive and complex predictive models they can query (folk physics, theory of mind of other agents, higher order knowledge of roads and places). But I agree, humans perform well despite not being particularly well adapted to driving. Given that, it would be foolhardy to proceed with vision and sound only because humans can get by with mostly just those. Better sensors push down the intelligence requirements for complex behavior. For example, insects as a group have a wider variety of sensors than any other group of organisms. With pin sized brains and milliwatt power, they forage, hunt, fly, walk and some even learn or communicate with an elaborate (combinatorial) language. Their array of specialized sensors plays a large role in allowing for their surprisingly rich sets of behavior. While I'm here, I'll also note that optical illusions are not things to get fooled by but instead, show the strength or assumptions of our predictive world models. Brains do not see the world as it is (see the checker shadow illusion and inattentive blindness), they predict based on, smooth, filter and adjust their inputs to more effectively act in the world. All inferential systems must have particular structural biases to do well in their target domain. In animals, between what was evolved and what is learned based on early environment; expectation and experience ends up top-down affecting what we see. It's very non-trivial -- many were surprised to learn for example, that even the "simple" retina receives inputs also from non-visual areas (and the details differ from species to species).

hyperbovine 10y ago

How does lidar see through a hedge?

xnzakg 10y ago
Probably was a radar, not a lidar.
mseebach 10y ago
Possibly infrared sensing? Some fancy IR cameras can see a human body through walls, so I guess it's not inconceivable that a LIDAR (which is already IR, I think?) could penetrate a hedge.
- swiley 10y ago
  You're thinking of far IR (typical black body radiation at room temperature for most materials) near IR is what has to be filtered out in web cams and what a lot of these LIDAR devices use, it behaves almost exactly like visible light.
willvarfar 10y ago
LIDAR can practically see through vegetation. Some individual beams miss the vegetation and reflect from things they hit on the far side, and the software can detect this. This is used a lot in mapping and research into e.g. forest canopies in the amazon. LIDAR has been extensively deployed on aircraft for this kind of purpose. I've seen high-res LIDAR scans made available by my country's state survey for e.g. archeologists and it has the 'true ground' through the vegetation. Its like the vegetation has been stripped away and has a clinical feel when rendered.
- mturmon 10y ago
  This is a good summary. Some lidars also offer two distance estimates per point, a first distance and a secondary distance. On the lidar I used that had this capability, the secondary distance was not always robust. But on permeable materials like vegetation, the secondary distance would typically indicate solid materials behind the initial curtain of material. Anyway, the presence of multiple distance returns in a small solid-angle area (whether from the above primary/secondary, or from nearby scan points) can indicate density of vegetation. You can certainly see "through" the small gaps in a hedge. Depending on the lidar, and the range, gaps as small as a few cm^2 could be enough (talking about vehicle-mounded lidar for autonomous navigation, not remote sensing of forest canopy).

Cybiote 10y ago

Humans have a bit more information than that -- tactile, proprioceptive and complex predictive models they can query (folk physics, theory of mind of other agents, higher order knowledge of roads and places). But I agree, humans perform well despite not being particularly well adapted to driving. Given that, it would be foolhardy to proceed with vision and sound only because humans can get by with mostly just those. Better sensors push down the intelligence requirements for complex behavior. For example, insects as a group have a wider variety of sensors than any other group of organisms. With pin sized brains and milliwatt power, they forage, hunt, fly, walk and some even learn or communicate with an elaborate (combinatorial) language. Their array of specialized sensors plays a large role in allowing for their surprisingly rich sets of behavior. While I'm here, I'll also note that optical illusions are not things to get fooled by but instead, show the strength or assumptions of our predictive world models. Brains do not see the world as it is (see the checker shadow illusion and inattentive blindness), they predict based on, smooth, filter and adjust their inputs to more effectively act in the world. All inferential systems must have particular structural biases to do well in their target domain. In animals, between what was evolved and what is learned based on early environment; expectation and experience ends up top-down affecting what we see. It's very non-trivial -- many were surprised to learn for example, that even the "simple" retina receives inputs also from non-visual areas (and the details differ from species to species).