Is it possible to deactivate surface collisions in Perspective mode, to have the same behaviour as in Free-Flight mode, and be able to pass through the surface?

If not, would it be appropriate to propose a feature request on this point?

FYI, I'm interested by this feature because I have an underground city, using tunnel networks, and it would be convenient to go underground in perspective mode to see it.

That's not possible to deactivate rn, no ...
The problems is ... how would the camera know to which y-height you want to focus (orbit around) .. right now it uses the surface ^^

Also please use our discord for feature-requests and questions.. its much better suited for discussions like this than github :)