I cannot figure out what “distance from base surface” means, would anyone explain for me?
Thx a lot！
Welcome to the discourse @alicia,
The meaning is that when you ask for any analysis calculation it creates a new geometry (mesh). The distance from surface means the offset from the original surface for the new one to be created. It avoids that 2 surfaces will stand on the same location and unpleasant flickering or smashed looking will appear.
-A.
Thx a lot I understand now!