The white things are LIDAR units. It's a laser range finder often used for robotics car competitions. It's the most accurate way to measure distance.
If you wonder how it works: the unit has a spinning mirror. It sends out pulses of laser light as the mirror spins and measures how quickly the light takes to return after it hits an object to return to a sensor on the unit. If you know how fast light moves and have a fast processor, you can measure distance.)
Because they are being used sideways, they sweep from sky to ground measuring distance. They are probably being used to "map" buildings as they drive by, so that the data could be used to create better 3D maps.
(They aren't perfect: reliability includes a variety of factors including environment [how do bushes and trees affect laser measurement] and distance [range may only be 50ft for instance])
If you wonder how it works: the unit has a spinning mirror. It sends out pulses of laser light as the mirror spins and measures how quickly the light takes to return after it hits an object to return to a sensor on the unit. If you know how fast light moves and have a fast processor, you can measure distance.)
Because they are being used sideways, they sweep from sky to ground measuring distance. They are probably being used to "map" buildings as they drive by, so that the data could be used to create better 3D maps.
(They aren't perfect: reliability includes a variety of factors including environment [how do bushes and trees affect laser measurement] and distance [range may only be 50ft for instance])