Yes, lidar bounces off surfaces at shallow angles to give false readings. Also, the long wavelength of IR means that lots of flattish surfaces are good mirrors.

Yes, lidar bounces off surfaces at shallow angles to give false readings. Also, the long wavelength of IR means that lots of flattish surfaces are good mirrors. In mobile robotics, glass panelled corridors are perceived very badly.[1] Passive depth from stereo usually has big holes where no features are detected[2]. That's why Kinect and the like project their own IR texture into the scene. Outdoors ambient IR overwhelms the projection unless you use powerful lasers. The upshot of this is that robots are vulnerable to banging into stuff, like bats. [1] I don't know for sure but it's likely that the right hand side of this map I found online has glass walls causing bad range data: https://i.pinimg.com/originals/e0/87/04/e08704b6dc925b575c2f1fe15e92be84.jpg https://i.pinimg.com/originals/e0/87/04/e08704b6dc925b575c2f... [2] If it doesn't, it's because the holes have been filled by interpolation - guessing what is there rather than observing it directly.