I’m curious how and where in the code the UE4 engine converts centimeters to meters, to keep the physic simulation smooth? I hope, that this is done at some point, like PhysX docs says:
Object scales that cause jittering
Simulations that use inches or centimeters as the basic unit (as is the default in 3dsmax) require a gravity factor on the order of 1000 and a skinWidth of 2.5. At these values, your simulation is likely to exhibit a lot of jitter straight off.
If you reduce all these values by a factor of 100 (to bring into meters scale), you should so no more jitter.
The reason for this is that there are other variables, such as NX_BOUNCE_TRESHOLD and NX_DEFAULT_SLEEP_LIN_VEL_SQUARED to name two, that also need to be scaled. The default values of all current and future variables are (and will be) based on meter units, so the safeguard is to use meters for your own PhysX data, if possible, or scale it whenever you pass data to and from the PhysX simulation.