Questions about varThresholdsq

[pengjili]

Great work!!! But there's one part I'm not quite clear about, regarding varThresholdsq. Specifically, what does this calculated value actually represent? And why is it compared with the square of the variance?

[Nussknacker]

Hi @pengjili

The reason using squared values is to avoid costly sqrt operations, it is just a performance optimization.
The variance threshold used to determine whether a cell is considered a "ground cell" (containing almost only ground points) is scaled by the distance from the sensor. This leads to a larger threshold for cells at greater distances because measurement accuracy declines with distance. To keep the variance threshold within reasonable bounds, it is limited to a minimum of the configured parameter "minimum_distance_factor" and a maximum of ten times this parameter.

I hope this helps clarify the calculation. Otherwise, don't hesitate to ask more questions. :)