Reply to post: Re: "...a [Lidar] blind spot low to the ground all around the car."

Uber self-driving car death riddle: Was LIDAR blind spot to blame?

Eddy Ito Silver badge

Re: "...a [Lidar] blind spot low to the ground all around the car."

Low is a relative term. Keep in mind a xc90 is 1766 mm or a couple inches shy of 6 feet tall and the LIDAR is roof mounted so it's likely easily over 6 feet. Depending on the vertical scan angle of the LIDAR there will be a blind spot created by a superposition of the roof of the car creating a largely rectangular cone the size of which is determined by how high the LIDAR unit is mounted and by the lowest angle it can scan.

If we assume the LIDAR is at 2 meters high and is mounted 1 meter from the edge of the roof (as the car is ~2 meters wide and I'm modelling it as a brick) this gives a maximum angle of 12.6 degrees below horizontal before the LIDAR beam is blocked by the roof outline. That puts the closest point on the ground the LIDAR unit can see at 8.9 meters (29.3 ft) away directly ahead and to the sides and 12.6 meters (41.4 ft) over the corner. If we move the LIDAR to 2.5 meters high these numbers drop to 3.5 meters (11.3 ft) and 4.9 meters (16 ft) respectively. The distance will be considerably greater toward the rear as the assumption here is that it is mounted 1 meter from the front edge of the roof and that would potentially place the rear edge considerably farther away decreasing the downward angle visible.

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