What would prevent using the same technique of only retaining the maximum Z direction return to tell the difference between a refracted rain drop and car bumper?
Perhaps it is that the rain drop refracts the beam to all sorts of other objects which can make it difficult to tell which actually has the longest Z-distance return?
If I understand correctly the airborne LIDAR works in the timedomain and is much more expensive, while the LIDAR on automobiles is much more affordable but works in the frequency domain...
Perhaps it is that the rain drop refracts the beam to all sorts of other objects which can make it difficult to tell which actually has the longest Z-distance return?