About Detecting Negative Objects as Non Ground?

[tlgkyn06]

Hello, I've been following you since patchwork v1. Congratulations on your successful work.

I would like to use your algorithm to also detect negative objects such as high slopes, holes, and small cliffs as non-ground. Which parameters should I change?
My autonomous vehicle specifically perceives the road as 'ground' when it's on the sidewalk. There is a 45 cm difference between the sidewalk and the road.