Not exactly sure what you are asking.
For ANY operation, the recommended maximum altitude is measured where the drone is physically located at any given time.
The guidelines for hobby/recreation flight state that you should remain under 400 AGL (above ground level).
If you launch and fly to an altitude of 400 feet AGL and then fly over the edge of a cliff that drops off 200 feet, then you will likely not be in compliance with the guideline unless you reduce the altitude of the drone.
Note that the Spark will ONLY show the altitude above the takeoff point. It doesn't know how far you are above the ground.