You have a million laser pulses to work with every second with the S3. Since you get to decide where each and every one of those pulses is aimed, your autonomous car probably wants to point most of them down the road ahead of it, with some off to the sides. But when the car is stopped at an intersection, it can “refocus” its LIDAR to the sides instead to be more effective at detecting cross traffic. This refocusing can happen dynamically and almost instantly, such that if your car is speeding down the road and spots a potential obstacle, it can focus as much of its LIDAR resources on that obstacle to collect the information that it needs to decide what to do next, while still continuing to collect (slightly sparser) data from everywhere else.

http://spectrum.ieee.org/cars-that-think/transportation/sensors/quanergy-solid-state-lidar