Constant radius corners and sloping ground?

[R Soul]

Does anyone know how real track builders create constant radius corners when the ground is not flat? Usually a track is designed in top view (not just BTB, but CAD and other methods too). However if you take a circle and project it down onto a slope (imagine a perfect shadow), the resulting line will no longer be a perfect curve from the driver's point of view.

In top view this corner is perfectly circular:

But when projected onto a steep slope like this (imagine just moving a node downwards):

I think the driver's experience would be that the corner's radius changes:

So, should a track's top view be changed to take this effect into account?

 

[Emery]

Laguna Seca (er, Mazda Raceway Laguna Seca) and Mosport (er, Canadian Tire Motorsport Park) both have published plans and they show the constant radius turns from a top view despite elevation changes.

 

[R Soul]

Thanks for your reply. I'm probably over-thinking things. I think I'll just plan constant radius corners and adjust the exits if the seem to get tighter.